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| AS8218 / AS8228 Highly Integrated Single Phase 2-Current Energy Metering Integrated Circuits with Microcontroller, RTC, Programmable Multi-Purpose I/Os and LCD Driver DATA SHEET 1. Key Features - - Precision single-phase, one or two current input energy measurement front-end including SigmaDelta modulators for A/D-conversion and digital signal processor (DSP). Low current consumption of 5mA, depending on MCU activity. Digital phase correction and selectable gain on both current channels for use with two current transformers (CT) or one CT and one shunt. Power-supply monitor (PSM) for power-on reset and reset when the supply voltage falls below a defined threshold. Customer programmable 8-bit 8051 compatible microcontroller (MCU). Programmable MCU clock with optional low power operating conditions. 2 x Universal Asynchronous Receiver / Transmitters (UART) for external communications such as programme download and debugging. Programmable watchdog timer (WDT) and external system reset pin. Real-time clock/calendar (RTC) with on-chip digital calibration and separate battery supply pin. On-chip voltage reference (VREF) with small temperature coefficient. Low power 3.0 - 4.0MHz crystal oscillator. SPI compatible interface for external EEPROM memory. Standard on-chip LCD driver (LCDD) interface. Programmable multi-purpose I/Os (MPIO) with selectable data direction, pull-up or pull-down resistors and drive strength. Mains current lead/lag status indication for reactive energy measurement. Low power battery operating mode for meter reading when Mains voltage is not present. The AS8218 and AS8228 ICs offer the following options: AS8218: 20 x 4 segment LCDD 9 x multi-purpose I/O (MPIO) AS8228: 24 x 4 segment LCDD 12 x multi-purpose I/O (MPIO) - 2. General Description The AS8218 / AS8228 are highly integrated CMOS single-phase energy metering devices for fully electronic LCD meter systems. The AS8218 / AS8228 have been designed to ensure the meters full compliance with the international Standards IEC62052 and ANSI. The AS8218 / AS8228 ICs include all the functions required for conventional 1 current or 2-current anti-tamper meters. The functions include precision energy measurement, an 8-bit microcontroller unit (MCU), an on-chip Liquid Crystal Display driver (LCDD), programmable multi-purpose Inputs/Outputs (MPIO), a real time clock/calendar (RTC) for complex tariff functions such as time-ofuse or maximum demand billing and a Serial Peripheral Interface (SPI) for reading data from and writing data to an external non-volatile memory (EEPROM). The AS8218 / AS8228 ICs have a dedicated energy measurement front-end, which includes an analog front-end and programmable Digital Signal Processor (DSP) from which active energy, mains voltage and mains current are provided. Reactive and apparent energy can also be calculated. The on-chip 8-bit 8051 compatible microcontroller is freely programmable and provides user access to the various functional blocks. The dedicated Universal Asynchronous Receiver / Transmitter (UART1) in the System Control block provides access to various system functions and blocks. A second UART (UART2) is also provided, which may for example be used for debugging. The on-chip memory includes 24kByte program memory and 1kByte data memory. The meter system designer can select the size of the external EEPROM memory from 1kByte to 32kByte (in binary steps). - - - - - - - - - - - - Revision 3.0, 31-May-06 Page 1 of 123 Data Sheet AS8218 / AS8228 An on-chip programmable watchdog timer (WDT) is available to automatically initiate a system reset if a regular `hold-off' signal is not detected. The system timing and real time clock (RTC) has a dedicated external battery supply pin (VDD_BAT), enabling the oscillator and RTC to continue during `power-down'. The RTC may be digitally calibrated for oscillator frequency accuracy. The LCD Driver (LCDD) block enables the display of information provided by the microcontroller, directly to the LCD. Two dedicated data register banks are provided to simplify programming, particularly in the case where the display data needs to be scrolled. The programmable multi-purpose I/O pins (MPIO) may be independently configured as inputs or outputs. All the I/O pins are programmable for data direction, pull-up/pull-down resistors and drive strength (4mA/8mA). Typical functions may include LED energy consumption pulse output, energy direction and fault condition indication depending on current 1 or current 2 being active for the energy calculation, push button for display scrolling, mains isolation relay control for prepayment meters, optical interface etc. An on-chip analog ground buffer (ABUF) and voltage reference (VREF) ensures that no external circuitry is required. A power-supply monitor (PSM) provides a reset, when VDD falls below a safe operating threshold. A reset pin (RES_N) is available for external system reset. The AS8218 / AS8228 ICs are available in LQFP64 plastic packages. Revision 3.0, 31-May-06 Page 2 of 123 Data Sheet AS8218 / AS8228 3. Typical Application Circuit 3.3V 3.3V + + LCD 3.3V XIN XOUT 32 33 Low Power Oscillator VDDA 7 Low Power Divider 13 VDDD 22 LBP0 LBP1 LBP2 LBP3 kWh Vrms Irms 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 9 LSD0 LSD1 LSD2 LSD3 LSD4 LSD5 LSD6 LSD7 LSD8 LSD9 LSD10 LSD11 LSD12 LSD13 LSD14 LSD15 LSD16 LSD17 LSD18 LSD19 LSD20 LSD21 LSD22 LSD23 IO0 IO1 IO2 IO3 IO4 IO5 IO6 IO7 IO8 IO9 IO10 IO11 LED DIRO FAULT VDD_BAT 31 RTC System Timing & RTC LOAD I1P 3 Analog Front End LCD Driver SDM I1N I2N 4 6 SDM I2P VP 5 1 DSP MCU SDM VN 2 I/Os Examples only 10 11 WDT RES_N 34 Multipurpose I/Os 12 15 16 17 18 19 26 27 28 Push-Button Reference pulses for calibration AS8228 only System Control UART1 23 20 24 25 S_N SI SO SC SPI 8 VSSA 14 VSSD 21 VSSD 29 TXD 30 RXD EEPROM S1 Q 2 3.3V W 3 VSS 4 8 VCC 3.3V HOLD 3.3V 7 6C 5D VI VO 3.3V + GND N L Figure 1: Typical application circuit of the AS8218 / AS8228 Revision 3.0, 31-May-06 AS8228 only Page 3 of 123 Data Sheet AS8218 / AS8228 4. Pin Out LSD19 LSD18 LSD17 LSD16 LSD15 LSD14 LSD13 LSD12 LSD11 LSD10 LSD23 LSD22 LSD21 LSD20 LSD19 LSD18 LSD17 LSD16 LSD15 LSD14 LSD13 LSD12 LSD11 LSD10 51 LSD9 LSD8 LSD9 50 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 64 63 62 61 60 59 58 57 56 55 54 53 52 VP VN I1P I1N I2P I2N VDDA VSSA IO0 IO1 IO2 IO3 VDDD VSSD IO4 IO5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 48 47 46 45 44 43 42 LSD7 LSD6 LSD5 LSD4 LSD3 LSD2 LSD1 LSD0 LBP3 LBP2 LBP1 LBP0 n.c. n.c. RES_N XOUT VP VN I1P I1N I2P I2N VDDA VSSA IO0 IO1 IO2 IO3 VDDD VSSD IO4 IO5 49 LSD8 48 47 46 45 44 43 42 n.c. n.c. n.c. n.c. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 LSD7 LSD6 LSD5 LSD4 LSD3 LSD2 LSD1 LSD0 LBP3 LBP2 LBP1 LBP0 n.c. n.c. RES_N XOUT AS8218 LQFP64 41 40 39 38 37 36 35 34 33 AS8228 LQFP64 41 40 39 38 37 36 35 34 33 VDD_BAT S_N SO VSSD TXD VDDD RXD XIN SC n.c. SI IO6 IO7 IO8 IO9 IO6 IO7 IO8 IO10 IO11 VDD_BAT S_N SO VSSD TXD 5. Pin Description Pin No. 1 2 3 Pin Name AS8218 VP VN I1P Pin Name AS8228 VP VN I1P AI AI AI Positive input for the voltage channel. VP is a differential input with VN. The typical differential voltage is 100mV peak. Negative input for the voltage channel. VN is a differential input with VP. Positive input for the first current channel. I1P is a differential input with I1N. The input gain is programmable depending on the desired current sensor. The typical differential voltage is 150mV peak (Gain = 4). Negative input for the first current channel. I1N is a differential input with I1P. The input gain is programmable depending on the desired current sensor. The typical differential voltage is 150mV peak (Gain = 4). Positive input for the second current channel. I2P is a differential input with I2N. The input gain is programmable depending on the desired current sensor. The typical differential voltage is 150mV peak (Gain = 4). Negative input for the second current channel. I2N is a differential input with I2P. The input gain is programmable depending on the desired current sensor. The typical differential voltage is 150mV peak (Gain = 4). Positive analog supply. VDDA provides the positive supply voltage for the analog circuitry. The required supply voltage is 3.3V 10%. Negative analog supply. VSSA is the ground reference for the analog circuitry. Programmable multi-purpose input/output, with selectable pull-up or pull-down resistors and selectable drive strength. Type Description 4 I1N I1N AI 5 I2P I2P AI 6 I2N I2N AI 7 8 9 VDDA VSSA IO0 VDDA VSSA IO0 S S DIO Revision 3.0, 31-May-06 VDDD RXD XIN n.c. n.c. SC SI Page 4 of 123 Data Sheet AS8218 / AS8228 Pin No. 10 11 12 13 Pin Name AS8218 IO1 IO2 IO3 VDDD Pin Name AS8228 IO1 IO2 IO3 VDDD Type Description DIO DIO DIO S Programmable multi-purpose input/output, with selectable pull-up or pull-down resistors and selectable drive strength. Programmable multi-purpose input/output, with selectable pull-up or pull-down resistors and selectable drive strength. Programmable multi-purpose input/output, with selectable pull-up or pull-down resistors and selectable drive strength. Positive digital supply. VDDD provides the positive supply voltage to the digital circuitry and is internally connected to pin 22. The required supply voltage is 3.3V 10%. Negative digital supply. VSSD is the ground reference for the digital circuitry. Programmable multi-purpose input/output, with selectable pull-up or pull-down resistors and selectable drive strength. Programmable multi-purpose input/output, with selectable pull-up or pull-down resistors and selectable drive strength. Programmable multi-purpose input/output, with selectable pull-up or pull-down resistors and selectable drive strength. Programmable multi-purpose input/output, with selectable pull-up or pull-down resistors and selectable drive strength. Programmable multi-purpose input/output, with selectable pull-up or pull-down resistors and selectable drive strength. 14 15 16 17 18 19 20 21 22 VSSD IO4 IO5 IO6 IO7 IO8 SI VSSD VDDD VSSD IO4 IO5 IO6 IO7 IO8 SI VSSD VDDD S DIO DIO DIO DIO DIO DIPD Serial peripheral interface (SPI) for external EEPROM: Serial data input. SI is a digital input with an on-chip pull-down resistor. S S Negative digital supply. VSSD is the ground reference for the digital circuitry. Positive digital supply. VDDD provides the positive supply voltage to the digital circuitry and is internally connected to pin 13. The required supply voltage is 3.3V 10%. Serial peripheral interface (SPI) for external EEPROM: Chip select (active low). Serial peripheral interface (SPI) for external EEPROM: Serial data output Serial peripheral interface (SPI) for external EEPROM: Serial clock Programmable multi-purpose input/output, with selectable pull-up or pull-down resistors and selectable drive strength. Programmable multi-purpose input/output, with selectable pull-up or pull-down resistors and selectable drive strength. Programmable multi-purpose input/output, with selectable pull-up or pull-down resistors and selectable drive strength. Universal Asynchronous Receiver/Transmitter (UART1) serial transmit data output. 23 24 25 26 27 28 29 30 31 32 S_N SO SC n.c. n.c. n.c. TXD RXD VDD_BAT XIN S_N SO SC IO9 IO10 IO11 TXD RXD VDD_BAT XIN DO DO DO DIO DIO DIO DO DIPU Universal Asynchronous Receiver/Transmitter (UART1) serial receive data input. RXD is a digital input with an on-chip pull-up resistor. S AI Battery backup supply voltage input for the system timing and real time clock (RTC). A 3.0 to 4.0MHz crystal may be connected across XIN and XOUT without the requirement for external load capacitors. Alternatively, an external clock signal may be applied to XIN. Revision 3.0, 31-May-06 Page 5 of 123 Data Sheet AS8218 / AS8228 Pin No. 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 Pin Name AS8218 XOUT RES_N n.c. n.c. LBP0 LBP1 LBP2 LBP3 LSD0 LSD1 LSD2 LSD3 LSD4 LSD5 LSD6 LSD7 LSD8 LSD9 LSD10 LSD11 LSD12 LSD13 LSD14 LSD15 LSD16 LSD17 LSD18 LSD19 n.c. n.c. n.c. n.c. Pin Name AS8228 XOUT RES_N n.c. n.c. LBP0 LBP1 LBP2 LBP3 LSD0 LSD1 LSD2 LSD3 LSD4 LSD5 LSD6 LSD7 LSD8 LSD9 LSD10 LSD11 LSD12 LSD13 LSD14 LSD15 LSD16 LSD17 LSD18 LSD19 LSD20 LSD21 LSD22 LSD23 Type Description AO See XIN above, for the connection of a crystal. When an external clock is applied to XIN, XOUT is not connected. System reset active low. Not connected Not connected AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO AO LCD back-plane driver output signal. LCD back-plane driver output signal. LCD back-plane driver output signal. LCD back-plane driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. LCD segment driver output signal. Note: Shaded pins above only available with AS8228 IC Revision 3.0, 31-May-06 Page 6 of 123 Data Sheet AS8218 / AS8228 PIN Types: S AI AO DIPD DIPU DO DIO Supply pin Analog Input pin Analog Output pin Digital Input pin with pull-down resistor Digital Input pin with pull-up resistor Digital Output pin Programmable Digital Input or Output pin Revision 3.0, 31-May-06 Page 7 of 123 Data Sheet AS8218 / AS8228 Table of Contents 1. 2. 3. 4. 5. 6. Key Features .........................................................................................................................................1 General Description ...............................................................................................................................1 Typical Application Circuit ......................................................................................................................3 Pin Out..................................................................................................................................................4 Pin Description ......................................................................................................................................4 Electrical Characteristics........................................................................................................................9 6.1 Absolute Maximum Ratings (Non-Operating) ......................................................................................9 6.2 Operating Conditions ........................................................................................................................9 6.3 DC/AC Characteristics for Digital Inputs and Outputs........................................................................ 10 6.4 Electrical System Specification ........................................................................................................ 11 Performance Graphs ............................................................................................................................ 12 Detailed Functional Description ............................................................................................................ 14 8.1 Energy Measurement Front End (Including DSP) .............................................................................. 16 8.2 LCD Driver (LCDD) ......................................................................................................................... 48 8.3 Programmable Multi-Purpose I/Os (MPIO) ........................................................................................ 54 8.4 Serial Peripheral Interface (SPI) ...................................................................................................... 64 8.5 External EEPROM Requirements ..................................................................................................... 70 8.6 8051 Microcontroller (MCU) ............................................................................................................. 77 8.7 System Control (SCT) ..................................................................................................................... 98 8.8 Serial Interface - UART1............................................................................................................... 105 Circuit Diagram.................................................................................................................................. 114 7. 8. 9. 10. Parts List........................................................................................................................................... 115 11. Packaging ......................................................................................................................................... 117 12. Product Ordering Guide ..................................................................................................................... 117 13. Collection of Formulae ....................................................................................................................... 118 14. Terminology ...................................................................................................................................... 121 15. Revision ............................................................................................................................................ 122 16. Copyright .......................................................................................................................................... 122 17. Disclaimer ......................................................................................................................................... 122 18. Contact ............................................................................................................................................. 123 Revision 3.0, 31-May-06 Page 8 of 123 Data Sheet AS8218 / AS8228 6. Electrical Characteristics 6.1 Absolute Maximum Ratings (Non-Operating) Stresses beyond the `Absolute Maximum Ratings' may cause permanent damage to the AS8218 / AS8228 ICs. These are stress ratings only. Functional operation of the device at these or any other conditions beyond those indicated under `Operating Conditions' is not implied. Caution: Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Parameter DC supply voltage Input pin voltage Electrostatic discharge Storage temperature Lead temperature profile Humidity non-condensing Symbol VDD Vin ESD Tstrg Tlead 5 85 % -55 Min -0.3 -0.3 Max +5.0 VDD+0.3 1000 125 Unit Notes V V V C Norm: IPC/JEDEC-020C Norm: MIL 883 E method 3015 6.2 Operating Conditions Symbol VDDA VSSA A-D VDDD VSSD VDD_BAT Tamb Isupp fosc 3.0 Min 3.0 0 -0.1 3.0 0 2.0 -40 3.3 25 5 3.579545 4.0 3.3 Typ Max 3.6 0 0.1 3.6 0 3.6 85 Unit V V V V V V C mA MHz Depending on MCU activity VDDA - VDDD VSSA - VSSD Referring to VSSD, typical 10 % Notes Parameter Positive analog supply voltage Negative analog supply voltage Difference of supplies Positive digital supply voltage Negative digital supply voltage Battery supply voltage Ambient temperature Supply current System clock frequency Revision 3.0, 31-May-06 Page 9 of 123 Data Sheet AS8218 / AS8228 6.3 DC/AC Characteristics for Digital Inputs and Outputs CMOS Input with Schmitt Trigger and Pull-up Resistor (RXD) Parameter High level input voltage Low level input voltage Low level input current Symbol VIH VIL IIL -100 Min 0.7 x VDD 0.3 x VDD -15 Typ Max Unit V V A Tested at VDD=3.6V and Vin=0V Notes CMOS Input (SI) Parameter High level input voltage Low level input voltage High level input current Symbol VIH VIL IIH 15 Min 0.7 x VDD 0.3 x VDD 100 Typ Max Unit V V A Tested at VDD=3.6V and Vin=3.6V Notes CMOS Outputs (TXD, SO, SC, S_N) Parameter High level output voltage Low level output voltage High level output current Low level output current Symbol VOH VOL IOH IOL -4 Min 2.5 0.4 4 Typ Max Unit V V mA mA Notes Tested at VDD=3.0V Tested at VDD=3.0V Tested at VDD=3.0V and Vout=VOH Tested at VDD=3.0V and Vout=VOL MPIO Inputs with Schmitt Trigger and Selectable Pull-up/Pull-down Parameter High level input voltage Low level input voltage High level input current Low level input current Symbol VIH VIL IIH IIL 15 -100 Min 0.7 x VDD 0.3 x VDD 100 -15 Typ Max Unit V V A A Tested at VDD=3.6V and Vin=3.6V; `pull-down' Tested at VDD=3.6V and Vin=0V; `pull-up' Notes MPIO Outputs with Programmable Drive Strength Parameter High level output current Low level output current High level output current Low level output current Symbol VOH VOL IOH IOL -4 Min 2.5 0.4 4 Typ Max Unit V V mA mA Notes Tested at VDD=3.0V Tested at VDD=3.0V If `4mA' is selected. Tested at VDD=3.0V and Vout=VOH If `4mA' is selected. Tested at VDD=3.0V and Vout=VOL Revision 3.0, 31-May-06 Page 10 of 123 Data Sheet AS8218 / AS8228 Parameter High level output current Low level output current Symbol IOH IOL Min Typ Max 8 Unit mA mA Notes If `8mA' is selected. Tested at VDD=3.0V and Vout=VOH If `8mA' is selected. Tested at VDD=3.0V and Vout=VOL -8 LCDD Outputs The Liquid Crystal display driver (LCDD) outputs are specified in the LCD Driver section of this data sheet. 6.4 Electrical System Specification Symbol |VVP| |VI1P|, |VI2P| |VI1P|, |VI2P| |VI1P|, |VI2P| fmains DR(I) DR(P) 45 600:1 2000:1 0.1 err(dr) err(temp) err(cosphi) err(VDD) J Vmains Imax BW 1.75 0.2 0.5 0.5 0.2 0.1 264 120 % % % % % % V(rms) A(rms) kHz Reading 1) Within operating temperature range, 1) From 1 to 0.5, 1) 1) 2) 240V + 10%, 3) 3) Min Typ 100 150 38 30 Max 212 212 54 42 65 Unit mVp mVp mVp mVp Hz Notes Referenced to VSSA Referenced to VSSA Referenced to VSSA Referenced to VSSA Parameter Input Signals Voltage channel input voltage Current channel input voltage (Gain=4) Current channel input voltage (Gain=16) Current channel input voltage (Gain=20) Mains frequency Dynamic range current Dynamic range power Accuracy Error variation over dyn. range Error variation over temperature Error variation over cos(phi) Error variation with VDD Output pulse jitter Mains voltage Measured current Measurement bandwidth Notes: 1) Errors determined during energy measurement using a demoboard and a reference meter with high accuracy (0.05%), which calculates the actual error. 2) Difference between largest and smallest error of 20 successive error samples; maximum meter constant: 1,600i/kWh; reference meter: 10,000 x DUT-meter-constant; measured at 5% Ib, Ib and I max . 3) What is used for system considerations/calculations. Revision 3.0, 31-May-06 Page 11 of 123 Data Sheet AS8218 / AS8228 7. Performance Graphs 0,5 0,4 0,3 0,2 0,5 0,4 VDD 3V6 VDD 3V3 0,3 0,2 PF=0.5 Error [% ] Error [%] 0,1 0 0,1 0 VDD 3V0 PF=0.8 -0,1 -0,2 -0,3 -0,4 -0,5 0,01 -0,1 -0,2 -0,3 -0,4 -0,5 PF=1.0 0,1 1 10 100 0,01 0,1 1 10 100 I [A] I [A] Graph 1: Error as a % of reading for gain setting 4 at 25C Graph 4: Error as a % of reading for PF=1, PF=0.8, PF=0.5 at 25C 0,5 0,4 0,3 0,2 0,5 0,4 0,3 VDD 3V3 0,2 Error [% ] Error [% ] 0,1 0 -0,1 -0,2 -0,3 -0,4 -0,5 0,01 0,1 0 VDD 3V6 -0,1 -0,2 -0,3 -0,4 -0,5 0,01 PF=0.5 PF=0.8 VDD 3V0 PF=1.0 0,1 1 10 100 0,1 1 10 100 I [A] I [A] Graph 2: Error as a % of reading for gain setting 16 at 25C Graph 5: Error as a % of reading for PF=1, PF=0.8, PF=0.5 at -40C 0,5 0,4 0,3 0,2 0,5 0,4 0,3 PF=0.5 VDD 3V0 0,2 E rro r [% ] Error [% ] 0,1 0 0,1 0 PF=0.8 VDD 3V3 -0,1 -0,2 -0,3 -0,4 -0,5 0,01 -0,1 -0,2 -0,3 -0,4 -0,5 0,01 PF=1.0 VDD 3V6 0,1 1 10 100 0,1 1 10 100 I [A] I [A] Graph 3: Error as a % of reading for gain setting 20 at 25C Graph 6: Error as a % of reading for PF=1, PF=0.8, PF=0.5 at 85C Revision 3.0, 31-May-06 Page 12 of 123 Data Sheet AS8218 / AS8228 0,5 0,4 0,3 0,2 3V0 3V3 0 0,5 0,4 0,3 0,2 Error [%] E rro r [% ] 0,1 0,1 0 -0,1 -0,2 -0,3 -0,4 -0,5 -0,1 -0,2 -0,3 -0,4 -0,5 0,01 0,1 1 I [A] 10 100 3V6 45 55 65 F [Hz] Graph 7: Error as a % of reading with variation in VDD Graph 9: Error as a % of reading with mains frequency variation 0,5 0,4 0,3 2 1,5 1 Gain 20 0,2 290V 230V 170V Error [%] Error [%] 0,1 0 0,5 0 -0,1 -0,2 -0,3 -0,4 -0,5 0,01 Gain 4 -0,5 -1 -1,5 -2 0,01 Gain16 0,1 I [A] 1 10 100 0,1 I [A] 1 10 100 Graph 8: Error as a % of reading with mains voltage variation Graph 10: Error as a % of reading using vconst for mains voltage value Revision 3.0, 31-May-06 Page 13 of 123 Data Sheet AS8218 / AS8228 8. Detailed Functional Description The AS8218 / AS8228 integrated circuits have a dedicated measurement front end, which is capable of measuring active and reactive energy, RMS mains voltage, RMS mains current as well as power factor. There are two completely separate differential current channel inputs, for measurement of both the Live and Neutral currents. The two current inputs may be connected to a shunt resistor (I1) and a current transformer (I2); of which the secondary winding is terminated with a burden resistor. Both current channels have programmable gains; thus it is possible to connect the shunt resistor to any of the two differential current inputs. The option to use two current transformers is also available. The AS8218 / AS8228 ICs may be programmed to accept either of the two measured currents for the energy calculation, or may be programmed to accept the larger of the two currents for the energy calculation. The AS8218 / AS8228 ICs may also be used for conventional 1-phase single current measurement applications, where only the Live current is measured. In this case, the I2P and I2N pins are left unconnected and the second current channel modulator can be powered down. The voltage channel input for measurement of the line voltage is also differential and is connected to a tap of a resistive divider of the line voltage. The resistive divider can be set to accommodate any line voltage standard (V mains ) including 100V, 110V, 220V, 230V and 240V. A 3.0 to 4.0MHz low power oscillator generates the system clock for the AS8218 / AS8228 ICs. The absolute clock frequency may be calibrated on-chip. A low power divider is used to generate a 1Hz clock for the on-chip real time clock/calendar (RTC). The supply voltage to the low power oscillator, the low power divider and the RTC may be buffered with an external battery in case of mains power dips or failures, which results in the AS8218 / AS8228 ICs power supply being interrupted. The LCD driver (LCDD) signals LSD0 ... LSD23 and LBP0 ... LBP3 can be directly connected to a liquid crystal display (LCD), which is used to display the various measured parameters. A total of 80 LCD segments may be driven by the AS8218 IC and 96 LCD segments may be driven by the AS8228 IC. The measurement data and display annunciators are fully programmable. The meter system designer should define the annunciators so that the end customer's specific meter system requirements are met. A maximum of twelve programmable multi-purpose input/output (MPIO) pins are available for various meter functions, for example light-emitting diodes (LED) to signal energy consumption, energy direction, fault condition, etc. These I/O pins may also be programmed for use as bi-directional communication channels such as an optical interface or an additional Universal Asynchronous Receiver/Transmitter (UART2) Interface, should it so be required. The AS8218 has 9 x MPIO pins, while the AS8228 has 12 x MPIO pins. A dedicated Serial Peripheral Interface (SPI) is also provided for the direct connection to an external EEPROM memory with a compatible serial peripheral interface. Depending on the meter system requirements, the external EEPROM memory capacity may be selected from 1kB up to 32kB, in binary steps. The on-chip 8051 compatible microcontroller performs all the required calculations and enables the user to customize the input and output configuration of the meter. The microcontroller has 24kB of program memory, 1kB data memory, a square root calculation facility and a second UART (UART2) for debugging purposes. A programmable watchdog timer is provided to automatically initiate a system reset when a regular hold-off signal is not detected by the watchdog timer. The watchdog timer is an optional function which is software enabled. Revision 3.0, 31-May-06 Page 14 of 123 Data Sheet AS8218 / AS8228 A dedicated serial Universal Asynchronous Receiver/Transmitter (UART1) Interface within the System Control is provided to communicate with the AS8218 / AS8228 ICs and perform all the required programming and reading of data, especially during the meter production process. The AS8218 / AS8228 ICs supply voltages (2 x VDDD and VDDA) are typically 3.3 Volts. These supply voltages should be derived from the V mains with the use of a standard voltage regulated power supply circuit. A typical 3.3 Volt power supply circuit is described later. An on-chip power supply monitor (PSM) ensures that a reset is generated independently of the supply voltage rise and fall times. Monitoring of the V mains is provided to ensure early power-down detection. A reset pin (RES_N) is also available for external system reset, which is active low. The RES_N pin can be left unconnected if not required. The individual functional elements of the AS8218 / AS8228 ICs, as well as the relationships between the various functional blocks are shown in the following block diagram. A detailed description of the AS8218 / AS8228 ICs system and the flexibility available to the kWh meter designer, through the system programmability is also described below: XIN XOUT VDD_BAT System Timing & Real Time Clock LBP3 ... 0 LCD Driver LSD23 ... 0 VP VN I1P I1N I2P I2N RXD TXD Energy Measurement Front End Analog Front End DSP 8051 MicroController Multi-purpose I/Os IO11 ... 0 UART1 System Control SPI SC S_N SO SI WDT RES_N Figure 2: AS8218 / AS8228 block diagram Revision 3.0, 31-May-06 Page 15 of 123 Data Sheet AS8218 / AS8228 8.1 Energy Measurement Front End (Including DSP) The Energy Measurement Front End is made up of the analog front end and the digital signal processing block (DSP), which performs the active energy measurement calculations for the microcontroller. The analog front end comprises of the three Sigma-Delta modulators for the sampling of the mains voltage, Line current and a second current channel, for the optional measurement of the Neutral current. Also included in the analog front end is the voltage reference, which provides the temperature stability to the Sigma-Delta modulators. Setting up for the optimum input conditions for the voltage and current channels is also described in this section. The digital signal processing block (DSP) provides the filtering and processing of the output data from the sigma-delta modulators and ensures that the specified measurement accuracy is provided by the AS8218 / AS8228. The DSP offers programming flexibility and provides for fast and efficient meter production calibration procedures. A power supply monitor (PSM) is also described in this section. The PSM ensures that a reset is generated independently of the rise and fall times of the supply voltage (VDD). Analog Front End The analog front end comprises of three identical Sigma-Delta modulators, which convert the differentially connected analog voltage and current inputs into digital signals. The two current inputs are gain adjustable to accommodate both directly connected or galvanically isolated current sensors. The on-chip voltage reference (VREF) is the most important contributor to the accuracy of the AS8218 / AS8228 ICs due to it providing temperature stability to the circuit. Considering that the voltage and current signals are multiplied to derive the energy value, errors introduced prior to multiplication function results in errors being multiplied. Thus the introduction of errors into the voltage and the current channel inputs will result in a doubling of the percentage error after multiplication at the energy output. The temperature coefficient of the VREF is specified at 30 ppm/K typical. Voltage Reference Specifications Parameter Output voltage Temperature coefficient Symbol Vref TK Min 1.217 Typ 1.219 30 Max 1.221 Unit V ppm/K Notes Current Inputs for Energy Calculation The AS8218 / AS8228 ICs have 2 identical mains current inputs, I1P/I1N and I2P/I2N, for measurement of both the Live and Neutral currents. Either of the two current inputs may be selected for calculating the energy value. These two differential current inputs are second order Sigma-Delta modulators, with each of the inputs being provided with selectable gains of 4, 16 and 20. The selectable gains are provided so that the AS8218 / AS8228 ICs may be easily adapted for use with either 2 current transformers or alternatively a shunt resistor and a current transformer for current sensing. The AS8218 / AS8228 ICs may also be used in a conventional single current configuration with either a current transformer or shunt resistor being used for current sensing. Revision 3.0, 31-May-06 Page 16 of 123 Data Sheet AS8218 / AS8228 The current input signal levels may be programmed by means of on-chip programmable gain settings. The required gain setting is selected as follows: Current Input Gain Settings Gain 20 16 4 20 16 4 Input Voltage -30mVV I1P 30mV -38mVV I1P 38mV -150mVV I1P 150mV -30mVV I2P 30mV -38mVV I2P 38mV -150mVV I2P 150mV Comments Shunt mode; default setting CT mode or shunt mode CT mode Shunt mode CT mode or shunt mode CT mode; default setting Current Inputs I1P, I1N Current Inputs I2P, I2N Notes: 1) V I1N and V I2N are connected to VSSA. 2) Refer to the Settings Register (SREG) in the DSP section for programming of the Gain Settings. For optimum operating conditions, the input signal at the Maximum Current (I max ) condition should be set at 30mVp, when the Gain = 20, or 150mVp, when the Gain = 4. The default Gain, the AS8218 / AS8228 ICs current input gain settings without any programming required, is Gain = 20 for the I1 input and Gain = 4 for the I2 input. The value of an ideal shunt resistor, may be calculated as follows: Assuming an I max rating of 60A (rms) 84.85A (peak), then a shunt value of 350 would be suitable. Rshunt = 30mVp 84.85 A p = 354 thus a standard 300 shunt resistor may be selected. The mains currents are sampled at 3.4956kHz, assuming that the recommended crystal oscillator frequency of 3.5795MHz, is used. The current transformer(s) must be terminated with a voltage setting resistor (R VS ) to ensure the optimum voltage input level to the current input(s) of the AS8218 / AS8228 ICs. The value of R VS is calculated as follows: R VS = Vin (p ) IL 2 = CT RMS secondary current at rated conditions (V m ains ; I max ) where I L V in(p) = The peak input voltage to the IC at rated conditions (V mains ; I max ). For example, if Gain = 4, V in(p) should be set at 150mVpeak. Example: A current transformer is specified at 60A/24mA and the Gain = 4: Revision 3.0, 31-May-06 Page 17 of 123 Data Sheet AS8218 / AS8228 R VS = Vin (p ) IL 2 = 150mV 24mA 2 = 4.42 4.3 Voltage Input for Energy Calculation The voltage channel input consisting of inputs VP and VN is differential, with VP connected to the tap of a resistor divider circuit of the line voltage and VN connected to VSSA. For optimum operating conditions, the input signal at VP should be set at 100mVp for the rated voltage condition. The resistor values for an ideal voltage divider may be calculated as follows: Assuming a V mains of 230V (rms) 325V (peak) and R2 = 470 (according to the voltage divider shown below), the value of R1A+R1B may be calculated as follows: Vmains R1A+R1B R2 Vin R1A + R1B = R2 x ( Vmains - Vin(P) ) Vin(P) = 470 x 325 V - 100mV = 1.53M 100mV thus R1A = 820k and R1B = 750k resistors may be selected. The mains voltage is also sampled at 3.4956kHz, assuming that the recommended crystal oscillator frequency of 3.5795MHz is used. Digital Signal Processing Block (DSP) The digital signal processing (DSP) block provides the signal processing required to ensure that the specified measured accuracy is performed and that the microcontroller (MCU) is provided with the appropriate data and protocol to perform all the required meter functions. For the description below, please refer to the following block diagram (Figure 3). The DSP makes allowance for phase correction of the two current channels (i1 and i2) within the Sinc decimation filters in the phase correction block. The applicable phase correction setting (pcorr_i1 or pcorr_i2) is selected (sel_i), depending upon which current (i1 or i2) is being used for the power calculation. The equalization filters on the voltage and current channels which may be by-passed (sel_equ), correct for the attenuation introduced by the decimation filters at the edge of the input frequency band, while the high pass filters, which may also be by-passed (sel_hp), eliminate any DC offsets introduced into the input channels. 3 Revision 3.0, 31-May-06 Page 18 of 123 Data Sheet AS8218 / AS8228 Independent calibration of the voltage (cal_v) and current signals (cal_i1 and cal_i2) is done after the voltage and current signals are provided for power calculation. This ensures that calibration of the voltage (sos_v), current channel 1 (sos_i1), current channel 2 (sos_i2) has no influence on the power (np) calibration. The iMux (current multiplexer) allows the selection of the applicable current for power calculation (sel_i), while the vMux (voltage multiplexer) allows the selection of either the mains voltage data, or a constant voltage value, vconst (sel_v). The multiplication of the appropriately selected voltage and current signals is then performed. After multiplication, the next multiplexer (sel_p) enables the selection of either instantaneous power or real power, which is filtered through a low pass filter, PLP. The direction indicator output (diro) is derived from the output of the power low pass filter (PLP). The following multiplexer (creep) allows the selection of the power signal, or blocks the power signal, depending on the required anti-creep and starting current thresholds, which may be set in the microcontroller. Only when constant voltage value (vconst) is selected by the vMux (voltage multiplexer) or when diro=1, it is necessary to derive the absolute power value, for measurement (Abs). The first pulse generator (Fast Pulse Gen) produces fast internal pulses, with the number of pulses being proportional to the measured energy. The multiplexer enables the selection of the appropriate pulse level (pulselev_i1 or pulselev_i2) depending on the current being used for energy measurement (sel_i). The output of the Fast Pulse Gen is always directly proportional to the LED pulse output, generated in the LED Pulse Gen. The LED output pulse rate is selectable (mconst). The polarity of the LED output pulses is also selectable (ledpol). To ensure that the power data transferred to the microcontroller (MCU) is identical to that of the LED pulses, the power accumulator (P_ACCU) counts the pulses generated by the Fast Pulse Gen. After a defined number of sampling periods (nsamp), an interrupt is sent to the MCU, for the MCU to collect the accumulated energy data. Revision 3.0, 31-May-06 Page 19 of 123 Data Sheet AS8218 / AS8228 pddeton Registers PD_DET alarm v ADC Phase Correction Equ Filter HP Filter X Square Accu sos_v cal_v i1 ADC Equ Filter HP Filter X Square Accu sos_i1 cal_i1 i2 ADC Equ Filter sel_equ HP Filter sel_hp sel_i X Square Accu sos_i2 cal_i2 vconst Mux sel_i iMux vMux sel_v pcorr_i1 pcorr_i2 X PLP <0? sel_p diro Mux "0" creep Mux sel_v Abs nsamp pulselev_i1 pulselev_i2 Mux sel_i Fast Pulse Gen P_ACCU np LED Pulse Gen mconst ledpol LED Figure 3: AFE block diagram Revision 3.0, 31-May-06 Page 20 of 123 Data Sheet AS8218 / AS8228 Phase Correction The DSP provides phase correction of the two current channels (i1 and i2) by means of the Sinc decimation filters in the phase correction block. Only one of the phase correction settings (pcorr_i1 or pcorr_i2) is valid at a time, depending on which current (i1 or i2) has been selected for the power calculation (sel_i). The phase correction step size is dependent upon the main oscillator frequency selected (f osc ) and the mains frequency (f mains ). Assuming a 3.579545MHz crystal oscillator frequency and 50Hz mains frequency, the phase can be corrected in steps of 2.41' or 0.04 degrees, which is equal to one oversampling sample, or one `unit' in the table below: pcorr Bit 8 0 0 0 0 0 0 0 1 1 1 1 1 1 Bit 7 1 1 0 0 0 0 0 1 1 1 1 0 0 Bit 6 1 1 1 1 0 0 0 1 1 0 0 0 0 Bit 5 1 1 1 1 0 0 0 1 1 0 0 0 0 Bit 4 1 1 1 1 0 0 0 1 1 0 0 0 0 Bit 3 1 1 1 1 0 0 0 1 1 0 0 0 0 Bit 2 1 1 1 1 0 0 0 1 1 0 0 0 0 Bit 1 1 1 1 1 1 0 0 1 1 0 0 0 0 Bit 0 1 0 1 0 0 1 0 1 0 1 0 1 0 Phase Correction [unit(s)] 255 254 ... 127 126 ... 2 1 0 -1 -2 ... -127 -128 ... -255 -256 3 One `unit' equals a certain phase shift related to the mains frequency: 1 unit = 360 x t ovs f f = 360 x mains = 360 x mains t mains f ovs f osc / 8 Phase =# unit x 360 x f mains fosc / 8 where fmains is the mains frequency and fOSC is the oscillator frequency. Example: 1 unit = 360 x f mains f osc / 8 255 units = 255 x 2.41' = 10.26 Revision 3.0, 31-May-06 Page 21 of 123 Data Sheet AS8218 / AS8228 Calculating Phase Correction Factors The measured phase_error in percentage is defined by the following formula phase _ error = cos( 60 + phase _ shift ) - cos( 60) x 100 cos( 60) [%] while the phase_shift in degrees, is calculated as follows: phase _ error [%] phase _ shift = arccos 1 + x cos( 60) - 60 100 phase _ correction = -phase _ shift The required phase correction factor can be determined from error measurements with a power factor (PF) less than 1. Assuming that at PF = 1 the meter has been calibrated and the error is approximately 0 for I cal (calibration current), the PF is reduced and the effect of phase differences results in an increased error (`phase_error'). Example: The phase_error at PF = 0.5 ( = 60) is measured to be 9.2 %. The related phase shift can be calculated using the following formula: phase _ error [%] phase _ shift = arc cos 1 + x cos 60 - 60 100 where the phase_error is the measured error in percentage and cos is the phase angle. For phase_error = 9.2[%] the phase_shift is -3.0 and the phase correction is 3.0. If f osc = 3.579545MHz and f mains = 50Hz, one phase correction unit represents 2.41', which is 0.04023. Thus the phase correction factor must be set to 3 .0 = 74.57 units 0.04023 = 75 units. The pcorr register has to be set to 4bh. Equalization Filters The equalization filters in the voltage and current channels correct for the attenuation effects introduced by the decimation filters around the frequency band limit. The resulting transfer curve after the equalization filter has approximately 0dB attenuation over the entire frequency band. The equalization filters may be by-passed (sel_equ), if required. Revision 3.0, 31-May-06 Page 22 of 123 Data Sheet AS8218 / AS8228 High-Pass Filters The high pass filters in the voltage and current channels, with corner frequencies of <10Hz, correct for DC offsets introduced into the input channels. Each of the voltage and current channels has a separate high pass filter in order to avoid any phase shift being introduced between the voltage and the two current channels. The high pass filters may also be by-passed (sel_hp), if so desired. Corner frequency: <10Hz RMS Calculations The DSP provides the voltage and current channel data in `sum-of-squares' format. To calculate RMS values from the voltage (sos_v) and current (sos_i1 and sos_i2), the following formula should be applied for the voltage and current respectively: Vrms = 1 nsamp 2 Vi , nsamp i=1 1 nsamp 2 Ii , nsamp i=1 nsamp where i=1 Vi 2 is the sos_v value Irms = nsamp where i=1 Ii 2 is the sos_i value nsamp should be selected in order to achieve coherent sampling as close as possible: e.g. f s = 3.4956kHz (f osc = 3.579545MHz) nsamp = 3496 should be selected if the MCU has to be interrupted every 1 second. When f mains = 50Hz, 70 mains periods are monitored. Refer to Squareroot Block (SQRT) for a detailed description of the programming sequence of the squareroot input operand. Revision 3.0, 31-May-06 Page 23 of 123 Data Sheet AS8218 / AS8228 Calibration of V and I Channels The single channel data may be corrected with a 16-bit calibration value. -5 The calibration range is [1 LSB; 2 - 1 LSB], step size (1 LSB): 3.052 x 10 . Calibration Register Setting 0000h 0001h ... 2000h ... 4000h ... 8000h ... FFFFh Value 0 0.00003052 (= 1 LSB) ... 0.25 ... 0.5 ... 1.0 ... 1.99996948 (2 - 1LSB) The V and I channel RMS calculation and calibration is described below (V and I channel are identical, thus only the I channel is shown): The ideal values after RMS calculations of voltage and current are: RMS_V(ideal) = 479(rms) RMS_I(ideal) = 292,110(rms) These values assume ideal input conditions with V in = 100mVp at rated conditions and I in = 30mVp (Gain = 20) at rated conditions. e.g: I max = 60A 292,110 60A I cal = 10A RMS _ I(ideal) = 292,110 = 48,685 10 A 6 Due to non-ideal components a different RMS value is calculated: RMS_I(actual). From this, the required calibration factor is calculated using the following formula: cal _ i = RMS _ I(ideal) RMS _ I(actual) The following formula calculates the actual value to be programmed into the calibration registers (cal_v; cal_i1; cal_i2): cal _ i(reg) = hex(round(cal _ i x 32,768 )) Constant Voltage Register (vconst) The vconst registers (9334h and 9335h) provide a predefined voltage value that can be used for calculating energy when the V mains is not available. Revision 3.0, 31-May-06 Page 24 of 123 Data Sheet AS8218 / AS8228 The default value of vconst is 2877 (0B3Dh) which translates into an equivalent V mains value of 311V. The energy is calculated using vconst and the selected current (i1 or i2) when sel_v in the SREG/Select register is set to `1'. The vconst value may be calculated according to the formula: vconst = RMS _ V x 2 x Example: RMS_V = 479 vconst = 479 x 2 x = 2,128 Note: When vconst is used for the calculation of energy, sel_p must be set to `0'. (Once the voltage channel has been calibrated, 479 is the typical value when V mains = 230V) Low Pass Filter for Real Power (PLP) When the instantaneous power is low pass filtered the result is practically a DC value for the power, which is termed real power. It is generally preferred to use real power to generate pulses for the calibration, as the duration between pulses is more constant (pulse jitter). Corner frequency: 18.6Hz The low pass filter ensures that the power output pulse jitter is minimised. Direction Indicator (DIRO) The direction indicator (DIRO) situated in the Status Register (Bit 4) defines the direction of the measured power. The direction is determined by the phase relationship between the Mains voltage and selected Mains current (i1 or i2). When bit 4 in the Status Register is `0', the Mains voltage and selected Mains current are in phase, thus indicating positive energy flow. When bit 4 in the Status Register is `1', the Mains voltage and the selected Mains current have a phase reversal, indicating negative energy flow. The energy calculation (np) is generated from positive energy, thus when DIRO = 1, the negative energy is converted to positive energy by the `Abs' block shown in Figure 3: AFE block diagram. Should the meter application require unidirectional energy measurement, the MCU can separately derive both the positive and negative energy values, depending on the status of the DIRO bit. Accumulator for Real Power (P_ACCU) To ensure that the power information transferred to the MCU is identical to that of the LED pulses, the P_ACCU counts the pulses generated by Fast Pulse Gen. After `nsamp' (nyquist) sampling periods an interrupt is sent to the MCU requesting to fetch the new energy information. (Interrupt line `IE.0' goes high and the `data available interrupt' (dai) flag in the SREG/Status register is set). The `ack' bit in the SREG/Status register is also set to 1. If the MCU takes the energy information, it has to reset the `ack' bit signalling that the energy information Revision 3.0, 31-May-06 Page 25 of 123 Data Sheet AS8218 / AS8228 has been taken. If the `ack' bit is not reset the P_ACCU will add the `old' energy information to the `new' energy information accumulated in the following cycle. In any event, the MCU must reset the dai flag in order to clear the interrupt. Wait for fast pulse New fast pulse? N Y Increment P_ACCU nsamp reached? N Y np = P_ACCU + np (old) P_ACCU = 0 IE.0 = 1 dai = 1 ack = 1 N ack = 0? Y Y np = 0 Note: The above flow chart assumes that the dai flag is always reset in time before the next interrupt is generated. Pulse Generation Two pulse generators are provided to ensure that virtually any LED pulse rate output can be programmed for display and calibration purposes. The first pulse generator (Fast Pulse Gen) produces fast internal pulses. These fast pulses are accumulated in the power accumulator (P_ACCU) for energy data transfer to the MCU. The second pulse generator (LED Pulse Gen) produces the LED output pulses (meter constant) from the fast internal pulses. This type of data interface ensures that the MCU receives exactly the same energy information as is displayed by the LED pulses. In case of `creep', the power samples to be added will be set to 0. This has the advantage that previously recorded energy is not lost and remains exactly the same. The following flow chart shows the basic flow diagram for pulse generation: Revision 3.0, 31-May-06 Page 26 of 123 Data Sheet AS8218 / AS8228 Wait for next power samples Add power sample to accu Accu> threshold defined by pulse_lev? N Y Generate pulse The Fast Pulse Gen output pulse rate always has the same relationship with the LED pulse rate defined by mconst. Only if LED is calibrated to a meter constant different from those provided in the mconst table, will the fast internal pulse rate be different. Formula for fast internal pulse rate (PR int ): PRint = 204,800 x T arg et Pulse Rate [i / kWh ] mconst where mconst is the meter constant. 1i = 1,000 x 3,600 [Ws ] PRint when 1i is one impulse representing an energy equivalent. Active Power Calibration (Pulse_lev) This paragraph describes how the active power measurement within the AS8218 / AS8228 ICs is calibrated. The parameter Pulse_lev is the main parameter which determines the output frequency of the Fast Pulse Gen. This frequency relates to the measured power and is the basis from which the output pulse rate is derived. Prior to system calibration, the appropriate value for the parameter Pulse_lev must be calculated to produce the required output pulse rate. The calibration exercise must accommodate all non-idealities that are present in the meter system. The Pulse_lev is specified such that a typical pulse rate of 204,800i/kWh can be achieved. During energy pulse calibration the correct Pulse_lev is determined in order to get the desired pulse rate. The default value for Pulse_lev is defined for I max =40A and V mains =230V. Default Pulse_lev: 570,950 Example for Pulse_lev calculations: Pulse _ lev(ideal) = 230 V 40 A x x Pulse _ lev( default ) Vmains Imax Revision 3.0, 31-May-06 Page 27 of 123 Data Sheet AS8218 / AS8228 V mains (V) 230 230 230 230 230 230 240 240 240 240 240 240 I max (A) 100 80 60 40 20 10 100 80 60 40 20 10 Pulse_lev (ideal) 228,380 285,475 380,633 570,950 1,141,900 2,283,800 218,864 273,580 364,774 547,160 1,094,321 2,188,642 Notes Default setting Pulse_lev(ideal) = 230/V mains x 40/I max x 570,950 Comparison Calibration Method The most common calibration method is the comparison of energy reading of the meter under test against a standard or reference meter. Normally, the standard, or reference meter has a considerably higher pulse rate than the meter under calibration. Reference meter output pulses are then counted between consecutive led pulses. To facilitate the calibration procedure, a pulse counter is provided in the MPIO block. In this case, the absolute calibration time and the calibration current are not relevant for the calibration cycle. The basic calibration setup is shown below: AS82xx Pulse Counter Reference Meter IO1 led PC I Figure 4: Basic setup for comparison calibration method (using IO1 as example input) Note: An I/O used as push-button input can be used for the input of the reference meter pulses during calibration. The standard or reference meter pulses are counted between two pulses from the meter to be calibrated. Ideally the sum of the pulses would exactly be the ratio between standard meter or reference pulse rate and the pulse rate of the meter under test. From the deviation the corrected Pulse_lev may be calculated. Pulse _ lev(corrected) = Pulse _ lev(ideal) x Ni , Na where Ni is the ideal number of pulses and Na is the actual number of pulses (PCNT register in MPIO). Revision 3.0, 31-May-06 Page 28 of 123 Data Sheet AS8218 / AS8228 The ideal number of pulses Ni is the ratio between the pulse rates, which is always >1. The formula for Ni is as follows: Ni = PR(ref ) , LED Pulse Rate(mconst ) where PR(ref) is the reference meter constant. The Pulse_lev (ideal) is calculated using the following formula: Pulse _ lev(ideal) = 230 V 40 A x x Pulse _ lev( default ) Vmains Imax Example The reference meter has a pulse rate, which is 10,000 times greater than the pulse rate of the AS8218 / AS8228 LED output. During a calibration cycle we measure 11,000 pulses between two LED pulses. Therefore the ideal Pulse_lev has to be changed by a factor of 10,000/11,000 = 0.909. LED Meter Constant Selection (mconst, 9330h) The LED pulses are derived directly from the fast internal pulses (204,800i/kWh). The `mconst' register in SREG specifies the LED pulse rate: MSB mconst[3] mconst[2] mconst[1] LSB mconst[0] Bit 7 6 5 4 3 Symbol mconst[3] Function Not used Not used Not used Not used Bit3 0 0 0 Bit2 0 0 0 0 1 1 1 1 0 0 0 0 1 Bit1 0 0 1 1 0 0 1 1 0 0 1 1 X Bit0 0 1 0 1 0 1 0 1 0 1 0 1 X LED Pulse Rate 204,800 102,400 51,200 25,600 12,800 6,400 3,200 1,600 800 400 200 100 100 2 mconst[2] 0 0 0 0 1 mconst[1] 0 1 1 0 mconst[0] 1 1 1 Revision 3.0, 31-May-06 Page 29 of 123 Data Sheet AS8218 / AS8228 If the target meter constant is different from one of the selectable (mconst) meter constants defined above: e.g. 1,000i/kWh (Target Pulse Rate) The same formula Ni = PR(ref ) can be used, but Ni is calculated using the Target Pulse Rate: LED Pulse Rate(mconst ) Ni = PR(ref ) T arg et Pulse Rate (Important: Select a pulse rate which is close to mconst, for the Target Pulse Rate, so that the Pulse_lev stays within reasonable limits.) After this calibration the energy equivalent of 1 fast pulse (1i) is different! Standard: internal pulse rate: 204,800i/klWh 1i = 1,000 x 3,600[Ws ] = 17.58 Ws 204,800 When a special pulse rate is required, the following formula applies: 1i = 1,000 x 3,600 LED PulseRate x [Ws ] 204,800 T arg etPulseRate Example: Assuming a pulse rate of 1,000 is required: 1,600 204,800 1,000 204,800 x 1,000/1,600 1i = 1,000 x 3,600[Ws ] = 28.13 Ws 204,800 x 1,000 / 1,600 Mains Current Leads/Lags Mains Voltage The i_lead flag in the SREG/Status register determines if the mains current leads the mains voltage or lags the mains voltage. The data is provided for reactive power calculation, to establish if the measured power is capacitive or inductive. Revision 3.0, 31-May-06 Page 30 of 123 Data Sheet AS8218 / AS8228 LED Output Timing The pulses on the LED output indicate the amount of energy that has been consumed over a certain period of time. Each pulse has an equivalent that can be set in the SREG/mconst register exactly. The unit is impulses per kWh (i/kWh). This output may be used for calibration. The polarity of the LED pulses may be selected via the ledpol bit in the SREG/Select Register for either positive or negative going pulses. Timing Diagram Timing Parameters Parameter Pulse width Symbol t1 Min Typ 80 Max Unit ms Notes 50% duty cycle is enabled when the LED period is less than 160ms. For mconst=0, t1 will be 17.9s. Register Interface to MCU One register block contains the data for the Meter Data Register (MDR) and the Settings Register (SREG), hence only one interface to the MCU is required. Meter Data Register (MDR) The meter data register is updated after `nsamp' samples. Then an interrupt is issued to the MCU, which may take the energy data and process them further on. When an interrupt is generated the `ack' bit in the SREG/Status register is set. If the MCU takes the data, it has to reset the `ack' bit. If the `ack' bit has not been reset by the MCU when a new set of data is ready, the previous np value will be added to the new one. In any case the dai flag in the SREG/Status register must be reset in order to clear the interrupt. Revision 3.0, 31-May-06 Page 31 of 123 Data Sheet AS8218 / AS8228 The following table shows the data which is available in the MDR: Register Name samptoend[7:0] samptoend[15:8] np[7:0] np[15:8] np[23:16] np[31:24] sos_v[7:0] sos_v[15:8] sos_v[23:16] sos_v[31:24] sos_v[35:32] sos_i1[7:0] sos_i1[15:8] sos_i1[23:16] sos_i1[31:24] sos_i1[39:32] sos_i1[47:40] sos_i1[53:48] sos_i2[7:0] sos_i2[15:8] sos_i2[23:16] sos_i2[31:24] sos_i2[39:32] sos_i2[47:40] sos_i2[53:48] Address 9300h 9301h 9302h 9303h 9304h 9305h 9306h 9307h 9308h 9309h 930Ah 930Bh 930Ch 930Dh 930Eh 930Fh 9310h 9311h 9312h 9313h 9314h 9315h 9316h 9317h 9318h Reset Value FFh FFh 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h Description Indicates how many samples are left (until nsamp), before the next interrupt is generated. Using this information the MCU can determine if it still has time to transfer the MDR data to the MCU memory. number of fast pulses, equivalent to energy information accumulated during nsamp samples sum of squares of voltage channel samples sum of squares of current channel 1 samples sum of squares of current channel 2 samples Notes: 1) MDR is read-only for MCU. (except for `MCU debug mode', then you can set the register values as described.) 2) Unused addresses will simply be ignored. The following flowchart describes how accumulators and registers work together: Revision 3.0, 31-May-06 Page 32 of 123 Data Sheet AS8218 / AS8228 Accumulate fast pulses (np); accumulate squares (sos) ack reset by MCU? N Y Reset np-register (MDR) nsamp reached? N Y Transfer sosaccus to registers (MDR/sos) Add P_ACCU to np-register Clear sos accus and P_ACCU Revision 3.0, 31-May-06 Page 33 of 123 Data Sheet AS8218 / AS8228 Settings Register (SREG) The settings register contains data stored by the MCU, which are used, for example, for calibration purposes, but also for general settings like input gain. Register Name pcorr_i1[7:0] pcorr_i1[8] pcorr_i2[7:0] pcorr_i2[8] cal_v[7:0] cal_v[15:8] cal_i1[7:0] cal_i1[15:8] cal_i2[7:0] cal_i2[15:8] pulselev_i1[7:0] pulselev_i1[15:8] pulselev_i1[23:16] pulselev_i2[7:0] pulselev_i2[15:8] pulselev_i2[23:16] mconst[3:0] nsamp[7:0] nsamp[15:8] vconst[7:0] vconst[13:8] Select Gains Status Address 9320h 9321h 9322h 9323h 9324h 9325h 9326h 9327h 9328h 9329h 932Ah 932Bh 932Ch 932Dh 932Eh 932Fh 9330h 9331h 9332h 9333h 9334h 9335h 9336h 9337h 9338h Reset Value 00h 00h 00h 00h 00h 80h 00h 80h 00h 80h 46h B6h 08h 46h B6h 08h 06h ACh 0Dh 3Dh 0Bh 80h 03h 00h Description Sets the phase correction for current channel i1. Sets the phase correction for current channel i2. Calibration factor for voltage channel. Only acts on sos_v data. Calibration factor for current channel i1. Only acts on sos_i1 data. Calibration factor for current channel i2. Only acts on sos_i2 data. Pulse_lev for fast pulse generation if current channel i1 is selected (sel_i). Pulse_lev for fast pulse generation if current channel i2 is selected (sel_i). Meter constant for LED pulse generation Not used Sets number of samples before next update of MDR. A predefined voltage value which may be used for energy calculation in the event of Vmains not being available. Select register Gain settings register Status register Note: Unused addresses will simply be ignored. Unspecified bits will also be ignored. Revision 3.0, 31-May-06 Page 34 of 123 Data Sheet AS8218 / AS8228 Select Register (Select, 9336h) MSB ledpol sel_p sel_i sel_v sel_hp LSB sel_equ Bit 7 6 5 4 Symbol Function ledpol sel_p Selects polarity of LED pulses: 0: negative going pulses Not used Not used Select between instantaneous and real power for pulse generation 0: instantaneous power 1: real power (low-pass filtered instantaneous power) Select current channel for power calculation (Fast Pulse Gen) 0: i1 1: i2 Select voltage channel data 0: selects voltage channel analog input 1: selects the predefined constant `vconst' Select high-pass filter 0: high-pass Select equalisation filter 0: equalizer 1: no high-pass 1: no equalizer 1: positive going pulses (default) 3 2 sel_i sel_v 1 0 sel_hp sel_equ Gain Settings Register (Gains, 9337h) MSB gain_i2[1] gain_i2[0] gain_i1[1] LSB gain_i1[0] Bit 7 6 5 4 3 Symbol Function gain_i2[1] Gain setting for current channel 2 modulator Not used Not used Not used Not used 2 gain_i2[0] Bit1 0 0 1 1 Bit1 Bit0 0 1 0 1 Bit0 0 1 0 1 Gain 4 16 16 20 Gain 4 16 16 20 1 gain_i1[1] Gain setting for current channel 1 modulator 0 gain_i1[0] 0 0 1 1 Revision 3.0, 31-May-06 Page 35 of 123 Data Sheet AS8218 / AS8228 Status Register (Status, 9338h) MSB creep mdm i_lead diro pddeton alarm dai LSB ack Bit 7 6 Symbol Function creep mdm Indicator for creep situation, used as disable signal for LED pulse generation 0: no creep 1: creep MCU Debug Mode flag Enables the MDR to be written by the MCU. This is useful for debugging when the programmer wants to know exactly what is received from the DSP block. 0: normal mode 1: debug mode as described later in the data sheet. Indicates if the mains current leads or lags the mains voltage. 0: mains current lags (inductive) 1: mains current leads (capacitive) DIRO indicator, signals when voltage and current are out of phase by 180 0: 0 phase difference 1: 180 phase difference Can only be read by MCU. Enables the power-down detector functionality 0: no PD_DET functionality 5 4 i_lead diro 3 2 pddeton alarm 1: PD_DET on Indicates when the Vmains is falling below a predefined threshold. If this happens an interrupt is generated and the alarm flag is set. The interrupt will be reset only when the alarm flag is reset. 0: no alarm 1: alarm that Vmains is low Data Available Interrupt flag Indicates that an interrupt has been generated because new meter data are available. 0: no interrupt 1: interrupt due to new data Set only by DSP. Resetable only by software (MCU). A clear of `dai' means that the irq is set back to 0. 1 dai 0 ack Acknowledge bit, indicates if MCU has transferred newly available data to its memory 1: Set by DSP, when data are ready on MDR. (not settable by MCU!) 0: Reset by MCU, when data have been taken. When ack gets reset the contents of MDR-np is set to zero. The `P_ACCU' always adds the contents of MDR-np to the last value just before it transfers new data to the MDR. Thus, if ack=0 the MDR-np is reset and nothing is added to the P_ACCU. If ack has not been cleared the np data is still available and is added to the P_ACCU. Current Channel Comparison The two current channels can be compared by the microcontroller (MCU), if the greater of the two currents is required for energy calculation. This is done by comparing the calculated RMS values of the two currents. The threshold for changing from I1 to I2 (or visa versa) can also be set in the MCU. Creep Detection The standards specify that no pulses must be generated when there is no current flow (`creep'). Additionally there is a threshold for current when the meter must generate pulses in any case (`starting current'). Therefore a detection circuit must guarantee that these two situations are under control. The AS8218 / AS8228 current channel data are evaluated in the MCU to find out if there is a `creep' situation. The related signal is used to stop the pulse generation if required. Revision 3.0, 31-May-06 Page 36 of 123 Data Sheet AS8218 / AS8228 MCU Debug Mode When mdm flag of SREG/Status register is set, the DSP block enters the MCU debug mode. Here the MDR can be written through the MCU interface. In this mode the DSP block is not allowed to write to the MDR. Special functionality: 1) ack set to 0 np is set to 0 (i.e. must be set again by MCU) 2) when ack is not reset by the MCU the np value is doubled, i.e. a shift left is done. Note: Also in debug mode an interrupt is generated after nsamp samples. Power Supply Monitor (PSM) The AS8218 / AS8228 ICs have an on-chip power supply monitor (PSM) that ensures a reset is generated independently of the supply voltage (VDD) rise and fall times. A built in hysteresis is provided to accommodate slow changes on the VDD, to ensure clean signal switching. Parameter Threshold positive edge Threshold negative edge Hysteresis Table 1: Symbol Vth,pos Vth,neg Hyst Min 2.6 2.2 100 Typ Max 2.9 2.6 Unit V V mV Notes Power supply monitor: Power-on reset specifications To ensure sufficient time is available to store the meter data in the EEPROM during power-down, it is necessary to detect the falling supply voltage as fast as possible. Should only the VDD be monitored, an external capacitor in the 3.3V power supply could sustain the VDD supply voltage even after the V mains has begun to fall. For this reason, the AS8218 / AS8228 ICs allow the monitoring of the V mains to ensure early power-down detection. The power-down detector function (PD_DET) is enabled in the SREG/Status register. An alarm signal is generated, when the V mains falls below a specified mains voltage threshold, which enables the MCU to react with sufficient time. It is also possible to calculate energy during power-down detection, taking a constant voltage value for calculation of the energy value. The mains voltage threshold is calculated as follows: Vmains (alarm) = Vmains x 512 RMS _ V(ideal) x 2 230 x 512 479 x 2 = = 173.8 VAC External System Reset (RES_N) An external reset pin (RES_N) is provided for system reset. RES_N is active LOW (i.e. logic `0' will initiate a system reset). A system reset via the RES_N pin is OR-ed with the main system power-on reset generated by the power supply monitor PSM. RES_N is internally pulled high. If not used, RES_N should be left unconnected. Revision 3.0, 31-May-06 Page 37 of 123 Data Sheet AS8218 / AS8228 System Timing and Real Time Clock (RTC) A low power crystal oscillator using a 3.0 to 4.0MHz crystal provides the AS8218 / AS8228 system timing. The low power oscillator is internally connected to a low power divider, which provides a 1Hz signal to the real time clock, which may be precision trimmed. VDD_BAT XIN XOUT Low Power Oscillator Low Power Divider 1Hz div[19:0] RTC Register Interface MCU Mclk Figure 5: System timing and RTC block diagram clk_1hz Low Power Oscillator (LP_OSC) The low power oscillator is connected to an external 3.0 to 4.0MHz crystal. The oscillator can be operated in two modes, namely normal mode or low power mode. The low power mode is operational when the remainder of the circuit is off (not operational). Should a suitable external clock signal be preferred, this may be directly connected to the XIN pin, which is fed through to output `Mclk'. In this case, XOUT is left unconnected. Parameter Current consumption, normal mode Current consumption, low power mode Frequency range Supply voltage range Duty cycle Symbol Iosc,norm Iosc,bat fosc VDD_BAT duty_cyc Min Typ 20 7 Max 50 Unit A A Notes VDD_BAT = 2VDC @ 25C 3.0 2.0 45 3.579545 3.3 4.0 3.6 55 MHz V % Low Power Divider (LP_DIV, 9130h - 9132h) The main oscillator output frequency (Mclk) is divided down to 1Hz for the real time clock (RTC). The option to use alternative crystal frequencies and still derive a 1Hz clock signal for the real time clock (RTC), is provided through this internally programmable divider. For power-saving reasons, the fast oscillator clock is first divided down by a fixed ratio (divide by 5) and then the programmable divider follows. Revision 3.0, 31-May-06 Page 38 of 123 Data Sheet AS8218 / AS8228 Mclk div5 programmable divider clk_1hz div[19:0] Parameter Input frequency range Supply voltage range Division factor Symbol fMclk VDD_BAT n Min 3.0 2.0 Typ 3.579545 3.3 Max 4.0 3.6 1,048,575 Unit MHz V Notes 1) The setting of div[19:0] is located in the RTC registers (addresses: 9132h - 9130h) Note: 1) The division factor n is effective on the frequency Mclk/5. It represents the actual division factor minus 1. Example: Calculate n for oscillator frequency 3,579,545Hz. The frequency after the div5 is 715,909Hz. Therefore, n must be 715,909 - 1 = 715,908. (Setting n = 1 means a division factor of 2) 2) n = 0 stops the clock. Real-Time Clock (RTC) The RTC can be directly accessed from the MCU via a dedicated interface register. Two alarm registers are provided to indicate a certain time instance, such as the start of a new month. In that case an interrupt is sent to the MCU. Constant frequency deviations of the crystal that is used can be trimmed to an accuracy of better than +/-1.4ppm. A seconds counter is provided which may be used for certain meter calculations. There is only one interrupt output. The source of the interrupt is indicated in the Control/Status 2 register. RTC Register Interface Time/ Calendar Registers Alarm Registers Seconds Counter Frequency Trim LP_DIV Setting MCU LP_DIV Revision 3.0, 31-May-06 Page 39 of 123 Data Sheet AS8218 / AS8228 RTC Registers Register Name Seconds / VL Minutes Hours Days Day of the Week Month / Century Years Control / Status 1 Control / Status 2 Seconds Timer Byte 0 Seconds Timer Byte 1 Minute Alarm 1 Hour Alarm 1 Day Alarm 1 Month Alarm 1 Years Alarm 1 Minute Alarm 2 Hour Alarm 2 Day Alarm 2 Month Alarm 2 Years Alarm 2 Divider Register Byte 0 Divider Register Byte 1 Divider Register Byte 2 Frequency Trim Address 9100h 9101h 9102h 9103h 9104h 9105h 9106h 9110h 9111h 9112h 9113h 9114h 9115h 9116h 9117h 9118h 9119h 911Ah 911Bh 911Ch 911Dh 9130h 9131h 9132h 9133h Reset Value 80h 00h 00h 01h 00h 01h 00h 10h 00h 01h 00h 00h 00h 01h 01h 00h 00h 00h 01h 01h 00h 84h ECh 0Ah 00h Notes [7:0] = div [7:0] (LP_DIV) [7:0] = div [15:8] (LP_DIV) [3:0] = div [19:16] (LP_DIV) Notes: 1) If illegal values (i.e. not defined in the following tables, e.g. `0', no BCD code, not correct last day of month, not correct leap year) are written to the time/date registers (00h - 06h), they are corrected to the first valid number (`automatic correction')! Then an interrupt is generated and the TSA flag in the Control/Status 2 register is set. 2) All other registers are not corrected (e.g. alarm info incorrect alarm is not met). 3) After power-up of VDD_BAT the time/date registers are stopped, the WAIT flag (Control/Status 1) is set. 4) Unused addresses will simply be ignored. Revision 3.0, 31-May-06 Page 40 of 123 Data Sheet AS8218 / AS8228 Control / Status 1 Register (9110h) MSB WAIT - LSB - Bit 7 6 5 4 Symbol Function WAIT Not used Not used Not used Indicates that RTC is waiting for a start signal. The start signal is WAIT being reset to 0. WAIT = 0 RTC running normally. (Clear by MCU.) WAIT = 1 Is set when time/calendar information is changed (access to registers 9100h to 9106h). While RTC is waiting for a start signal, 1Hz clock is still gated to the MPIOs. Not used Not used Not used Not used 3 2 1 0 - Register bit assignment: (Unassigned bits in the registers are marked with `-`. If these bits are read they will return zero value. Writing these bits has no effect.) Control / Status 2 Register (9111h) MSB TSA A2F A1F STF AIE2 AIE1 LSB SIE Bit 7 Symbol Function TSA Time Setting Alarm: Indicates when an impossible time/date has been set and it has been corrected by st st the RTC automatically, e.g. 31 February 1 February. An interrupt will be generated and TSA is set to 1. The interrupt is cleared by setting TSA=0 (done by MCU (software)). 6 5 4 3 A2F A1F STF Not used Set to logic 1 when an alarm 2 occurs and maintains this value until software clears it. Indicates the source of the interrupt. Cannot be set by software. When the flag is cleared, also the interrupt is cleared. Set to logic 1 when an alarm 1 occurs and maintains this value until software clears it. Indicates the source of the interrupt. Cannot be set by software. When the flag is cleared, also the interrupt is cleared. Set to logic 1 when a seconds timer interrupt occurs and maintains this value until software clears it. Indicates the source of the interrupt. Cannot be set by software. When the flag is cleared, also the interrupt is cleared. AIE2 = 0; alarm 2 interrupt disabled AIE2 = 1; alarm 2 interrupt enabled AIE1 = 0; alarm 1 interrupt disabled AIE1 = 1; alarm 1 interrupt enabled SIE = 0; seconds counter interrupt disabled SIE = 1; seconds counter interrupt enabled 2 1 0 AIE2 AIE1 SIE Revision 3.0, 31-May-06 Page 41 of 123 Data Sheet AS8218 / AS8228 Note: Alarm interrupts are only generated on rising clk_1hz edges (using system clock for detection). This means that enabling an alarm after that will not generate an interrupt. Seconds / VL Register (9100h) MSB VL sec.6 sec.5 sec.4 sec.3 sec.2 sec.1 LSB sec.0 Bit 7 Symbol Function VL VL = 0; reliable clock / calendar information guaranteed. VL = 1; clock / calendar information is NOT guaranteed. This bit is set after power-up of VDD_BAT. It can be cleared by software only. These bits represent current seconds value encoded in BCD format (values from 0 to 59). 6 5 4 3 2 1 0 sec.6 sec.5 sec.4 sec.3 sec.2 sec.1 sec.0 Minutes Register (9101h) MSB 0 min.6 min.5 min.4 min.3 min.2 min.1 These bits represent current minute value encoded in BCD format (values from 0 to 59). LSB min.0 Hours Register (9102h) MSB 0 0 hour.5 hour.4 hour.3 hour.2 hour.1 These bits represent the current hours value encoded in BCD format (values from 0 to 23). LSB hour.0 Days Register (9103h) MSB 0 0 day.5 day.4 day.3 day.2 day.1 These bits represent current day value encoded in BCD format (values from 1 to 31). Note on leap years: `00' years in general are no leap years unless the complete year can be divided by 400 (e.g. 2000). Since the year 2000 has passed already, this chip will not consider a leap year for `00' years. LSB day.0 Revision 3.0, 31-May-06 Page 42 of 123 Data Sheet AS8218 / AS8228 Day of the Week Register (9104h) MSB 0 0 0 0 0 weekd.2 weekd.1 LSB weekd.0 Bit 7 6 5 4 3 2 Symbol weekd.2 Function Not used Not used Not used Not used Not used These bits represent the current weekday value. Bit2 0 0 Bit1 0 0 1 1 0 0 1 Bit0 0 1 0 1 0 1 0 Day Sunday Monday Tuesday Wednesday Thursday Friday Saturday 1 weekd.1 0 0 1 0 weekd.0 1 1 Month / Century Register (9105h) MSB C 0 0 month.4 month.3 month.2 month.1 LSB month.0 Bit 7 Symbol C Function Century bit. C = 0; indicates the year is 20xx C = 1; indicates the year is 21xx `xx' indicates the value held in Years register. This bit is modified when Years register overflows from 99 to 00. 6 5 4 month.4 Not used Not used These bits represent the current month value encoded in BCD format. Bit4 0 0 Bit3 0 0 0 0 0 Bit2 0 0 0 1 1 Bit1 0 1 1 0 0 Bit0 1 0 1 0 1 Month January February March April May 3 month.3 0 0 0 Revision 3.0, 31-May-06 Page 43 of 123 Data Sheet AS8218 / AS8228 Bit 2 Symbol month.2 Function 0 0 0 0 0 1 1 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 1 0 1 0 1 0 1 0 June July August September October November December 1 month.1 0 1 0 month.0 1 1 Year Register (9106h) MSB year.7 year.6 year.5 year.4 year.3 year.2 year.1 These bits represent current year value encoded in BCD format (value from 0 to 99). The Alarm 1 or 2 is generated when the programmed time has been reached (seconds = 0!). LSB year.0 Minute Alarm Register (1/2) (9114h/9119h) MSB 0 mina.6 mina.5 mina.4 mina.3 mina.2 mina.1 These bits represent minute alarm information encoded in BCD format (values from 0 to 59). LSB mina.0 Hour Alarm Register (1/2) (9115h/911Ah) MSB 0 0 houra.5 houra.4 houra.3 houra.2 houra.1 These bits represent hour alarm information encoded in BCD format (values from 0 to 23). LSB houra.0 Day Alarm Register (1/2) (9116h/911Bh) MSB 0 0 daya.5 daya.4 daya.3 daya.2 daya.1 These bits represent day alarm information encoded in BCD format (values from 1 to 31). LSB daya.0 Month / Century Alarm Register (1/2) (9117h/911Ch) MSB C 0 0 mona.4 mona.3 mona.2 mona.1 LSB mona.0 These bits represent current month alarm value encoded in BCD format (value from 1 to 12). Please see also the `month assignments' table above. Revision 3.0, 31-May-06 Page 44 of 123 Data Sheet AS8218 / AS8228 Year Alarm Register (1/2) (9118h/911Dh) MSB yeara.7 yeara.6 yeara.5 yeara.4 yeara.3 yeara.2 yeara.1 These bits represent the year alarm value encoded in BCD format (value from 0 to 99). LSB yeara.0 Setting the Time The time can be set by writing to the respective time and calendar registers. When this is done the clock stops, the WAIT bit is set and the control waits for the WAIT bit to be reset (by the MCU or through System Control). When the WAIT bit is reset the clock gate will be opened and the RTC starts running. Alarms When time and one of the alarm registers match (seconds = 0), an interrupt is generated. The source of the interrupt is indicated in the A[1|2]F register bits in the Control/Status 2 register. The alarm generation can be disabled using the AIE1/2 bits. When the rest of the chip is off, there is no clock for the MCU interface, hence no alarm will be generated. The MCU interface is reset with the `res' signal which is coming from the PSM, i.e. all Status 2 bits are reset to default, which means that after MCU power-up it has to set the appropriate alarms again. (After power-up the MCU has to check what the time is, and has to decide what the next appropriate alarms will be.) Seconds Timer (9112h, 9113h) The seconds counter block, if enabled (SIE bit of Control/Status 2 register), generates an interrupt every n seconds. `n' is the number of seconds specified in the Seconds Timer registers 9112h (Byte 0) and 9113h (Byte 1). When an interrupt is sent, the flag STF is set. The Seconds Timer register is not BCD coded. Seconds counter start value: Seconds counter count direction: Condition for interrupt generation: 0000h up Seconds counter register value = Seconds Timer register value Note: 0000h in the timer register means that no interrupt must be generated. RTC Calibration (clk_1Hz) When using the real-time clock (RTC) it is essential that the 1Hz signal to the real-time clock is accurate. There are many possible external influences on the crystal oscillator frequency including the absolute crystal frequency itself and the parasitic and oscillator capacitor values. These influences alone can contribute to a significant change in the oscillator frequency. In this case, it is necessary to perform a calibration of the 1Hz signal through the `Programmable Divider' located in the 'Low Power Divider'. The procedure for trimming the RTC via the 'Programmable Divider' is explained below: Assuming a crystal frequency of 3.579545 MHz Revision 3.0, 31-May-06 Page 45 of 123 Data Sheet AS8218 / AS8228 The Programmable Divider follows a fixed 'Divide by 5' divider, thus the default value to the Programmable Divider is: 3.579545 / 5 = 715909 (default value to Programmable Divider) Therefore: A change of 1Hz in this default value is equal to: 1 / 715909 = 1.397 ppm Measure the deviation in the clk_1Hz frequency output provided by the AS8218 / AS8228 ICs Assuming an error of +690 ppm is measured (faster than real-time) Thus +690 / 1.397 = 493.915 = 494 Therefore 494 must be added to the default value: 715909 + 494 = 716403 (dec) = 0A EE 73 (hex) Divider Register Byte 2 = 0A Divider Register Byte 1 = EE Divider Register Byte 0 = 73 The RTC is then calibrated to within +/- 1.4 ppm Frequency Trimming (9133h) A further option for clk_1Hz frequency trimming is available. In this case only the 5 lower bits of register `Frequency Trim' (9133h) are used as defined in the following table. FREQ_TRIM[4:0] Correction [ppm] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 87.0 81.2 75.4 69.6 63.8 58.0 52.2 46.4 40.6 34.8 29.0 23.2 17.4 11.6 5.8 0 -5.8 -11.6 -17.4 -23.2 -29.0 Seconds per Day 1 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 0 0 -1 -1 -2 -2 Seconds per Day 2 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 -1 -1 -2 -2 -3 Revision 3.0, 31-May-06 Page 46 of 123 Data Sheet AS8218 / AS8228 FREQ_TRIM[4:0] Correction [ppm] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 0 0 1 1 0 0 1 1 0 0 0 1 0 1 0 1 0 1 0 1 0 -34.8 -40.6 -46.4 -52.2 -58.0 -63.8 -69.6 -75.4 -81.2 -87.0 -92.8 Seconds per Day 1 -3 -3 -4 -4 -5 -5 -6 -6 -7 -7 -8 Seconds per Day 2 -3 -4 -4 -5 -5 -6 -6 -7 -7 -8 -8 The table specifies 2 successive days with (possibly) a different number of seconds that have to be added or subtracted per day. `day1/day2' are repeated continuously. The RTC is always adjusted at the same time: 00:00 a.m. and 30 seconds. (The 30 seconds is required to avoid conflicts with alarm settings, which are defined to occur at 0 seconds.) Subtraction means that the specified number of 1Hz pulses is ignored. This has the effect that the clock stands still for the specified number of seconds. Example: A crystal has a frequency that is 30ppm higher than specified. Therefore the RTC will run faster. Thus, the RTC has to correct in the negative direction, by subtracting seconds. Value `11011' (-29.0) will be chosen which means that on day1, 2 seconds are subtracted, then on the next day 3 seconds are subtracted, then 2 seconds again and so on. Battery Backup Operation The AS8218 / AS8228 ICs contain a real-time clock (RTC) circuit, which must continue to operate even when the mains supply voltage (V mains ) is interrupted. A battery backup facility is provided for this purpose at pin VDD_BAT. The low power oscillator (LP_OSC), low power divider (LP_DIV) and the real time clock (RTC) are all supplied from the VDD_BAT pin. The recommended battery backup circuit is shown below. The battery is connected to the VDD_BAT pin via one or two diodes. The external VDD is also connected to the VDD_BAT pin via a diode, with the battery backup only providing supply to the AS8218 / AS8228 ICs when the external VDD is interrupted. external VDD VDD_BAT + Revision 3.0, 31-May-06 Page 47 of 123 Data Sheet AS8218 / AS8228 8.2 LCD Driver (LCDD) selvlcd lcdd_pd VDD VREG LBP0 Voltage Level Generation LCD Drive LBP1 LBP2 LBP3 LSD0 VSS LSD23 LCDD Control Data Register1 Data Register2 MCU Figure 6: LCD driver block diagram The on-chip LCD driver (LCDD) is a peripheral block, which interfaces to almost any liquid crystal display (LCD) having a multiplex rate of 4. It generates the drive signals to directly drive multiplexed LCDs containing up to four backplanes and up to 24 segments per backplane. The AS8218 has a 20 x 4 LCDD, while the AS8228 has a 24 x 4 LCDD. The data registers receive and store the display information, which is to be sent to the display. The LCDD control block decodes the information into the select lines for the single segments using a specific timing. The LCD voltage can be selected to adjust the contrast of the display, as required. The selvlcd[2:0] register bits enable the setting of the LCD contrast by selecting one of the defined LCD voltage levels. The contrast can be improved with a higher voltage, however the contrast is also dependent upon the crystal frequency. Revision 3.0, 31-May-06 Page 48 of 123 Data Sheet AS8218 / AS8228 Typical Display The LCD above is a typical example of those used in electricity meter applications and consists of a number of digits (generally up to 8 digits) including decimal points. Typically, annunciators (`kWh', `Volt', etc.) are also included to signify the type of data on display. LCD Drive (LCD_DRIVE) LCD drive mode is 1/4duty, 1/3bias. 4 back planes - 24 segment drives (maximum) All other parameters are listed in the table below: - Parameter LCD frame frequency LCD voltage LCD segment and back plane drive voltages Symbol fLCD VLCD V3 V2 V1 V0 Min 33 2.3 0.95 x VLCD Typ 39.4 2.5 VLCD Max 44 2.75 1.05 x VLCD Unit Hz V V V V mV k pF Notes 1) for selvlcd='000' 0.95 x 2/3VLCD 2/3VLCD 1.05 x 2/3VLCD 0.95 x 1/3VLCD 1/3VLCD 1.05 x 1/3VLCD VSS -20 0 20 100 300 LCD DC component LCD drive impedance LCD load on each driver pin VDCLCD RLCD Cload Note: 1) These frequencies are derived from the master clock (3MHz; 3.58MHz; 4MHz) using a divider of 90,909. Revision 3.0, 31-May-06 Page 49 of 123 Data Sheet AS8218 / AS8228 LCDD Control (LCDD_CTRL) including Input and Config Registers In the control block of the LCD driver there are two registers. Each of these registers may contain data to be displayed. With a special bit (921Eh, bit 0), it is possible to select one of the two register banks for display. Each register defines the settings for the different segment and plane select lines. The following table specifies the allocation of the register bits: LSD0 LBP0 LBP1 LBP2 LBP3 reg[0] reg[1] reg[2] reg[3] LSD1 reg[4] reg[5] reg[6] reg[7] LSD2 reg[8] reg[9] reg[10] reg[11] LSD3 reg[12] reg[13] reg[14] reg[15] LSD4 reg[16] reg[17] reg[18] reg[19] LSD5 reg[20] reg[21] reg[22] reg[23] LSD6 reg[24] reg[25] reg[26] reg[27] LSD7 reg[28] reg[29] reg[30] reg[31] LSD8 reg[32] reg[33] reg[34] reg[35] LSD9 reg[36] reg[37] reg[38] reg[39] LSD10 LBP0 LBP1 LBP2 LBP3 reg[40] reg[41] reg[42] reg[43] LSD11 reg[44] reg[45] reg[46] reg[47] LSD12 reg[48] reg[49] reg[50] reg[51] LSD13 reg[52] reg[53] reg[54] reg[55] LSD14 reg[56] reg[57] reg[58] reg[59] LSD15 reg[60] reg[61] reg[62] reg[63] LSD16 reg[64] reg[65] reg[66] reg[67] LSD17 reg[68] reg[69] reg[70] reg[71] LSD18 reg[72] reg[73] reg[74] reg[75] LSD19 reg[76] reg[77] reg[78] reg[79] LSD20 LBP0 LBP1 LBP2 LBP3 reg[80] reg[81] reg[82] reg[83] LSD21 reg[84] reg[85] reg[86] reg[87] LSD22 reg[88] reg[89] reg[90] reg[91] LSD23 reg[92] reg[93] reg[94] reg[95] AS8228 only Notes: 1) Each of the register bits represents one of the segments of the digits or a decimal point or one of the annunciators. 2) reg[x]=0: Segment is turned off; reg[x]=1: Segment is turned on. Revision 3.0, 31-May-06 Page 50 of 123 Data Sheet AS8218 / AS8228 The complete register is organized in bytes according to following table: Register Name reg1[7:0] reg1[15:8] reg1[23:16] reg1[31:24] reg1[39:32] reg1[47:40] reg1[55:48] reg1[63:56] reg1[71:64] reg1[79:72] reg1[87:80] reg1[95:88] reg2[7:0] reg2[15:8] reg2[23:16] reg2[31:24] reg2[39:32] reg2[47:40] reg2[55:48] reg2[63:56] reg2[71:64] reg2[79:72] reg2[87:80] reg2[95:88] use_reg Address 9200h 9201h 9202h 9203h 9204h 9205h 9206h 9207h 9208h 9209h 920Ah 920Bh 9210h 9211h 9212h 9213h 9214h 9215h 9216h 9217h 9218h 9219h 921Ah 921Bh 921Eh Reset Value 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h Description AS8228 only AS8228 only Bit 0: Selects register to be used. 0: Data Register 1 1: Data Register 2 Select VLCD level. See table in LCD Voltage Select Register. Bit 0: Power-down of the LCDD analog part. 0: Display on 1: Display off selvlcd[2:0] lcdd_pd 921Fh 9220h 00h 01h Notes: 1) Unused registers will simply be ignored. 2) All the registers are write only. Read operations always return 0. Revision 3.0, 31-May-06 Page 51 of 123 Data Sheet AS8218 / AS8228 LCD Display Data Select Register (USE_REG, 921Eh) The use_reg register selects either Data Register 1 or Data Register 2 for display on the LCD. Select `0' for Data Register 1 and `1' for Data Register 2. MSB - LSB use_reg LCD Voltage Select Register (SELVLCD, 921Fh) The LCD voltage select register, SELVLCD enables variation of the LCD contrast by selecting on of the 8 preset voltage levels. MSB selvlcd.2 selvlcd.1 LSB selvlcd.0 Bit 7 6 5 4 3 2 Symbol selvlcd.2 Function Not used Not used Not used Not used Not used These bits set the LCD voltage level for the LCD contract setting. Bit2 0 0 Bit1 0 0 1 1 0 0 1 1 Bit0 0 1 0 1 0 1 0 1 VLCD 2.5V 2.5714V 2.6428V 2.7142V 2.7856V 2.8570V 2.9284V 3.0V 1 selvlcd.1 0 0 1 0 selvlcd.0 1 1 1 LCD Power-Down (LCDD_PD, 9220h) The lcdd_pd register enables the analog part of the LCDD to be powered-down. Select `0' for LCD display on and `1' for LCD display off. MSB - LSB lcdd_pd Revision 3.0, 31-May-06 Page 52 of 123 Data Sheet AS8218 / AS8228 Drive Signals: Timing and Levels The following graphic shows examples of the timing of the drive signals. LSD0 LSD1 LSD2 LSD3 LSD4 LSD5 LBP0 LBP1 LBP2 LBP3 CLKLCD Frame LBP0 V3 V2 V1 V0 LBP1 V3 V2 V1 V0 LBP2 V3 V2 V1 V0 LBP3 V3 V2 V1 V0 Figure 7: LCD multiplexing waveform LSD0 V3 V2 V1 V0 LSD1 V3 V2 V1 V0 LSD2 V3 V2 V1 V0 LSD3 V3 V2 V1 V0 LSD4 V3 V2 V1 V0 LSD5 V3 V2 V1 V0 Revision 3.0, 31-May-06 Page 53 of 123 Data Sheet AS8218 / AS8228 8.3 Programmable Multi-Purpose I/Os (MPIO) Config Register sel_in sel_pupd en_io sel_drv UART2 rxd2 txd2 en_io0 InputMultiplexer [11:0] out_io0 in_io0 IO0 DATA REGISTERS MCU Input Register [11:0] out_mux Output Register [11:0] Output Multiplexer [11:0] led clk_1hz sel0_io[x] sel1_io[x] register[x] led txd2 clk_1hz IO11 out_io[x] Pulse Counter sel_refp [11:0] Figure 8: MPIO block diagram A total of 9 bidirectional multi-purpose I/O pins (MPIO) are provided with the AS8218 and 12 bidirectional multipurpose I/O pins with the AS8228, which may be used for a variety of purposes. All the I/Os can be freely programmed as inputs or outputs, with the option of either a pull-up or pull-down resistor. The drive strength of the individual I/O pins may also be programmed. On start-up all the I/O pins are disabled. Furthermore, a pulse counter is available, which can be used for calibration purposes (`comparison calibration method': Between two LED pulses the pulses from a reference meter with much higher pulse rate are counted. The result is used to calculate the calibration factor.). MPIO Registers All the MPIO registers are listed in the table below. The individual register functions are then described in detail. Register Name Config MAKE_IRQ0 MAKE_IRQ1 OUT_MUX0 OUT_MUX1 Address 9500h 9501h 9502h 9503h Reset Value 00h 00h 00h 00h Notes Revision 3.0, 31-May-06 Page 54 of 123 Data Sheet AS8218 / AS8228 Register Name OUT_MUX2 SET_EN0 SET_EN1 SEL_DRV0 SEL_DRV1 SEL_PUPD0 SEL_PUPD1 SEL_IN_RXD2 SEL_IN_REFP Address 9504h 9505h 9506h 9507h 9508h 9509h 950Ah 950Bh 950Ch Reset Value 00h 00h 00h 00h 00h 00h 00h 04h 03h Notes Input IN0 IN1 950Dh 950Eh 00h 00h Output OUT0 OUT1 OUT2 OUT3 OUT4 OUT5 OUT6 OUT7 OUT8 OUT9 OUT10 OUT11 950Fh 9510h 9511h 9512h 9513h 9514h 9515h 9516h 9517h 9518h 9519h 951Ah 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h AS8228 only Pulse counter PCNT0 PCNT1 PCNT2 951Bh 951Ch 951Dh 00h 00h 00h Status STATUS0 STATUS1 951Eh 951Fh 00h 00h Note: Unused addresses are ignored. Revision 3.0, 31-May-06 Page 55 of 123 Data Sheet AS8218 / AS8228 MAKE_IRQ0/MAKE_IRQ1 (9500h/9501h) The MAKE_IRQ registers specify if an interrupt should be generated after the related I/O input has changed. The I/O pin, which caused the interrupt, will be indicated in the STATUS0/STATUS1 flag registers. IOx: 0: no interrupt on signal change 1: generate an interrupt on signal change MAKE_IRQ0 MSB IO7 MAKE_IRQ1 MSB 0 0 0 0 IO11 IO10 AS8228 only IO9 IO6 IO5 IO4 IO3 IO2 IO1 LSB IO0 LSB IO8 OUT_MUX0/OUT_MUX1/OUT_MUX2 (9502h/9503h/9504h) The OUT_MUX registers specify the source signal for each of the I/O outputs. Every 2 bits are used as select signals for the 4-way output multiplexer of the designated I/O. OUT_MUX0 MSB IO3: sel1 OUT_MUX1 IO3: sel0 IO2: sel1 IO2: sel0 IO1: sel1 IO1: sel0 IO0: sel1 LSB IO0: sel0 MSB IO7: sel1 OUT_MUX2 IO7: sel0 IO6: sel1 IO6: sel0 IO5: sel1 IO5: sel0 IO4: sel1 LSB IO4: sel0 MSB IO11: sel1 IO11: sel0 IO10: sel1 IO10: sel0 IO9: sel1 IO9: sel0 IO8: sel1 AS8228 only The following table shows the settings for the output signal options: LSB IO8: sel0 sel1 0 0 1 1 sel0 0 1 0 1 Output Signal Notes register[x] led txd2 clk_1hz 80ms pulse width Revision 3.0, 31-May-06 Page 56 of 123 Data Sheet AS8218 / AS8228 SET_EN0/SET_EN1 (9505h/9506h) The SET_EN registers set the en_io signal of the related I/O pin. The en_io enables the tri-state output buffer so that the I/O pins operate as outputs. IOx: 0: disable output (I/O used as input) 1: enable output SET_EN0 MSB IO7 SET_EN1 IO6 IO5 IO4 IO3 IO2 IO1 LSB IO0 MSB 0 0 0 0 IO11 IO10 AS8228 only IO9 LSB IO8 SEL_DRV0/SEL_DRV1 (9507h/9508h) The SEL_DRV registers select the current drive strength for all the I/Os that have been selected as outputs: IOx: 0: 4mA 1: 8mA SEL_DRV0 MSB IO7 SEL_DRV1 IO6 IO5 IO4 IO3 IO2 IO1 LSB IO0 MSB 0 0 0 0 IO11 IO10 AS8228 only IO9 LSB IO8 SEL_PUPD0/SEL_PUPD1 (9509h/950Ah) The SEL_PUPD registers select either a pull-up or pull-down resistor for each of the I/O pins: IOx: 0: pull-down 1: pull-up SEL_PUPD0 MSB IO7 SEL_PUPD1 IO6 IO5 IO4 IO3 IO2 IO1 LSB IO0 MSB 0 0 0 0 IO11 IO10 AS8228 only IO9 LSB IO8 Revision 3.0, 31-May-06 Page 57 of 123 Data Sheet AS8218 / AS8228 SEL_IN_RXD2 (950Bh) The SEL_IN_RXD2 register selects which I/O input is used for the special input signal `rxd2' (UART2 receive input). Any one of the I/Os from IO0 to IO11 may be selected for this purpose. The select bits are defined in the following table: MSB 0 0 0 0 sel3 sel2 sel1 LSB sel0 MSB 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 0 0 1 1 0 0 1 1 0 0 1 1 LSB 0 1 0 1 0 1 0 1 0 1 0 1 Input IO0 IO1 IO2 IO3 IO4 IO5 IO6 IO7 IO8 IO9 IO10 IO11 AS8228 only SEL_IN_REFP (950Ch) The SEL_IN_REFP register selects which I/O input is to be used for reference pulses. Any one of the I/Os from IO0 to IO11 may be selected for this purpose. The select bits are defined in the following table: MSB 0 0 0 0 sel3 sel2 sel1 LSB sel0 MSB 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 1 1 0 0 1 LSB 0 1 0 1 0 1 0 Input IO0 IO1 IO2 IO3 IO4 IO5 IO6 Revision 3.0, 31-May-06 Page 58 of 123 Data Sheet AS8218 / AS8228 MSB 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 1 0 0 1 1 LSB 1 0 1 0 1 Input IO7 IO8 IO9 IO10 IO11 AS8228 only IN0/IN1 (950Dh/950Eh) The IN registers (input registers) store the input data from the I/O pins. These registers are continuously updated by the `Mclk' (main clock). IN0 MSB IO7 IN1 IO6 IO5 IO4 IO3 IO2 IO1 LSB IO0 MSB 0 0 0 0 IO11 IO10 AS8228 only IO9 LSB IO8 OUT0 ... OUT11 (950Fh - 951Ah) The OUT registers (output registers) contain the output data to be sent to the I/O pins (through the multiplexers). OUT0 MSB 0 OUT1 0 0 0 0 0 0 LSB IO0 MSB 0 OUT2 0 0 0 0 0 0 LSB IO1 MSB 0 OUT3 0 0 0 0 0 0 LSB IO2 MSB 0 0 0 0 0 0 0 LSB IO3 Revision 3.0, 31-May-06 Page 59 of 123 Data Sheet AS8218 / AS8228 OUT4 MSB 0 OUT5 0 0 0 0 0 0 LSB IO4 MSB 0 OUT6 0 0 0 0 0 0 LSB IO5 MSB 0 OUT7 0 0 0 0 0 0 LSB IO6 MSB 0 OUT8 0 0 0 0 0 0 LSB IO7 MSB 0 OUT9 0 0 0 0 0 0 LSB IO8 MSB 0 0 0 0 AS8228 only OUT10 0 0 0 LSB IO9 MSB 0 0 0 0 AS8228 only OUT11 0 0 0 LSB IO10 MSB 0 0 0 0 AS8228 only 0 0 0 LSB IO11 PCNT0/PCNT1/PCNT2 (951Bh/951Ch/951Dh) The PCNT registers (pulse counter registers) contain the result of the pulse counting for calibration purposes. PCNT0 MSB b7 b6 b5 b4 b3 b2 b1 LSB b0 Revision 3.0, 31-May-06 Page 60 of 123 Data Sheet AS8218 / AS8228 PCNT1 MSB b15 PCNT2 b14 b13 b12 b11 b10 b9 LSB b8 MSB b23 b22 b21 b20 b19 b18 b17 LSB b16 The maximum reference pulse frequency is defined below: Parameter Reference pulse frequency Symbol frefp Min Typ Max 120 Unit kHz Notes STATUS0/STATUS1 (951Eh/951Fh) The STATUS registers contain the irq flag register bits for each of the I/Os, the COUNT register bit which signals when a pulse counting should be started and the CINT flag bit which indicates when pulse counting has been completed. The irq flag registers are cleared by software only (MCU), but they cannot be set by software. The COUNT register bit can be set and reset by software (MCU). The COUNT register bit is cleared, when the pulse counter is finished and an interrupt has been generated. STATUS0 MSB IO7 STATUS1 IO6 IO5 IO4 IO3 IO2 IO1 LSB IO0 MSB COUNT CINT 0 0 IO11 IO10 AS8228 only IO9 LSB IO8 Notes: 1) IOx: 0: no change on input x 1: input x has changed 2) When an interrupt on an IO change has been generated, the signal irq is reset after the related flag has been cleared. 3) CINT is a flag, which indicates that the pulse counting has finished. When CINT is cleared, the irq is cleared. Pulse Counter A synchronous pulse counter is used. It is started after the COUNT bit has been set. The first led pulse is used for synchronisation. The second led pulse starts counting the reference pulses from the specified I/O input. Revision 3.0, 31-May-06 Page 61 of 123 Data Sheet AS8218 / AS8228 Timing: COUNT led Gate refp counted refp CINT Notes: 1) The COUNT signal is synchronized with `led'. 2) COUNT is reset and CINT is set using clk and checking for falling edge on Gate. 3) The PCNT register is only updated when counting is finished. Example: Select IO3 as the pulse reference input. Meter is 220V mains ; I max = 20A Meter constant: 1,600imp/kWh Reference meter constant: 16 million imp/kWh Register settings: MPIO SET_EN0 SEL_IN_REFP DSP mconst (9505h): (950Ch): (9330h): IO3 bit = 0 (output disabled) 02h 07h (Ideal) Pulse_lev (932Ch - 932Ah) = 570,950 x 230 V 40 A x 220 V 20 A = 1,193,804 12374Ch 932Ah: 4Ch 932Bh: 37h 932Ch: 12h Procedure: Status1 (951Fh): 80h starts pulse counting. When pulse counting is completed CINT bit in Status1 = 1. The status of the CINT bit in Status1 may be checked to confirm that the pulse counting is complete. Alternatively, the time between 2 pulses may be calculated to determine the count cycle time (the first pulse is used for synchronization and the second pulse starts the count cycle). Following the pulse counting cycle, the number of pulses counted can be read from PCNT0/PCNT1/PCNT2 (951Bh/951Ch/951Dh). Revision 3.0, 31-May-06 Page 62 of 123 Data Sheet AS8218 / AS8228 The ideal number of pulses counted assuming the meter is perfectly calibrated would be: Ni = 16,000,000 = 10,000 1,600 Assuming that we count 11,000 pulses, the (Ideal) Pulse_lev must be changed by the factor: 10,000/11,000 = 0.909 The new Pulse_lev = 1,193,804 x 0.909 = 1,085,168 108EF0h 932Ah: F0h 932Bh: 8Eh 932Ch: 10h Revision 3.0, 31-May-06 Page 63 of 123 Data Sheet AS8218 / AS8228 8.4 Serial Peripheral Interface (SPI) The Serial Peripheral Interface (SPI) represents a synchronous, bit serial 4-wire interface for full-duplex data transfer. It's primarily used here to communicate with an external EEPROM memory, which must fulfil the requirements described below. The EEPROM is selectable in size from 1kByte to 32kByte in binary steps. The SPI always operates in master mode, whereas the EEPROM works in slave mode. The bootloader controls the SPI during system start up. After that it is available to the MCU for free programming. SPI Signals Name SI SO SC S_N Type Input Output Output Output Description Serial input from slave device Serial output to slave Clock output to slave device Chip select output to slave device (low active) EEPROM S_N EEP_S_N EEP_SC EEP_SI EEP_SO 3.3V EEP_HOLD_N EEP_WP_N SPI Master SC SO SI AS8218/ AS8228 Figure 9: Typical SPI connection to an EEPROM Many EEPROMs provide a HOLD_N (hold protocol) pin and a WP_N pin (write protect), which must be held `1', otherwise the operation is blocked. During startup phase, the bootloader takes control over the SPI and generates the read out sequence automatically. Key Features - Standard 4 wire synchronous serial interface (SI, SO, SC, S_N) Master mode operation only 8-bit word length (variable transmit/receive word optional) Shift clock SC high when idle MSB is always transmitted first Four selectable clocking schemes (clock idle state / clock phase) Selectable SPI clock rate divider (from mcu_clk/2 to mcu_clk/65536) Three maskable interrupts (transmission complete, overrun, collision) Revision 3.0, 31-May-06 Page 64 of 123 Data Sheet AS8218 / AS8228 Each protocol starts by putting S_N to low level and ends by putting S_N to high again. If S_N goes high before the normal end of the protocol, the current protocol is terminated, the internal SPI state control logic is reset. The SO line state is X (don't care). When operating (S_N = 0), the data is shifted out on the falling edge of SC and incoming data is sampled on the rising edge of SC. TS_N_setup 1/fSC=TSC Tbyte_to_byte TS_N_hold S_N (out) Shift out data at SO with falling edge of SC SC (out) 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 Sample input data SI on rising edge of SC SO (out) X DO7 DO6 DO5 DO4 DO3 DO2 DO1 DO0 DO7 DO6 DO5 DO4 DO3 DO2 DO1 DO0 X SI (in) X DI7 DI6 DI5 DI4 DI3 DI2 DI1 DI0 DI7 DI6 DI5 DI4 DI3 DI2 DI1 DI0 X Transfer of 1st Data byte Transfer of 2nd Data byte Figure 10: SPI timing diagram Note: SO is shifted out on the falling edge of SC and SI is sampled on the rising edge (clock scheme: CPHA=1, CIDLE=1). For mcu_clk = 4 MHz (max) Parameter TS_N_setup TS_N_hold Tbyte_to_byte TSC TSC_LOW TSC_HIGH Description Time between S_N going low and first SC falling edge Time between last SC rising edge and S_N going high Time between two data bytes (LSB last to MSB next) SC serial clock period (= 1/FSC) SC serial clock minimum low time SC serial clock minimum high time MCU_clk cycles 36 6 12 4 2 2 Min 9 1.5 3 1 0.5 0.5 Units s s s s s s SPI Registers Register Name SSPCON SSPCLKDIV SSPSTAT SSPBUF Address Description 9400h 9401h 9402h 9403h Control register Clock divider register Status register Data register Revision 3.0, 31-May-06 Page 65 of 123 Data Sheet AS8218 / AS8228 Control Register (SSPCON, 9400h) The control register is used for enabling the SPI-interrupts and to control the chip select of the SPI. MSB IETR IEOV IECO IECS CSO AUTO LSB - Bit 7 Symbol Function IETR Transmit interrupt enable Issued after data register has been serially loaded with new data (slave mode) or if data has been shifted out after write access (master mode) 0: disable 1: enable Overrun interrupt enable Issued if ITRA still set and new data serially arrived 0: disable 1: enable Write collision interrupt enable Issued if data register is written during transmission 0: disable 1: enable Chip select interrupt enable Issued if chip-select pin is activated during master/slave mode 0: disable 1: enable Chip select output state in master mode if AUTO = 0 Inverted state of output signal S_N 0: S_N = `1' 1: S_N = `0' (active) Not used 1: Automatically activates the S_N (= '0') after data has been written to the data register and deactivates S_N (= '1') after transfer completed 0: S_N depends on the CSO bit ( manual S_N setting) Not used 6 IEOV 5 IECO 4 IECS 3 CSO 2 1 AUTO 0 - Recommended programming for SSPCON with no interrupts enabled: Mode S_N Auto mode Manual S_N=1 (inactive) Manual S_N=0 (active) SSPCON 02h 00h 08h Revision 3.0, 31-May-06 Page 66 of 123 Data Sheet AS8218 / AS8228 Clock Divider Register (SSPCLKDIV, 9401h) The clock divider register contains control bits to configure the clock-divider, to set-up the serial-clock SC, to enable the SPI and to select master or slave mode. MSB ENBL CIDLE CPHA M/S CLKDIV.3 CLKDIV.2 CLKDIV.1 LSB CLKDIV.0 Bit 7 Symbol ENBL Function SPI enable. Enables the SPI interface 1: enable 0: disable Serial clock SC idle state 1: SC idles high 0: SC idles low 6 CIDLE CIDLE Bit6 0 0 1 CPHA Bit5 0 1 0 1 SC Idle 0 0 1 1 Data shifted Input sampled out on SC on SC falling rising rising falling rising falling falling rising 5 CPHA Serial clock SC phase Data is samples and shifted out according to CIDLE/CPHA 1 Note: The CIDLE/CPHA set at 1 1 is used internally by most standard available EEPROMs 4 3 Master/Slave mode 1: Master mode, must be `1' 0: Slave mode (stops SPI operation), there is no slave mode available CLKDIV.3 Clock divider exponent Bit3 Bit2 In master mode, SPI output clock SC is CLKDIV+1 0 0 MCU_CLK / 2 0 0 M/S 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 Bit1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 Bit0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 SC-Rate 1:2 1:4 1:8 1 : 16 1 : 32 1 : 64 1 : 128 1 : 256 1 : 512 1 : 1,024 1 : 2,048 1 : 4,096 1 : 8,192 1 : 16,384 1 : 32,768 1 : 65,536 2 CLKDIV.2 0 0 0 0 1 1 1 1 1 CLKDIV.1 0 CLKDIV.0 1 1 1 1 The SPI output clock SC, which is derived from the mcu clock (mcu_clk) may be divided down as shown in the table above. Revision 3.0, 31-May-06 Page 67 of 123 Data Sheet AS8218 / AS8228 It is important to note, that the mcu_clk may also be divided down as described under MCUCLKDIV Register (`mcu_clk'). Therefore the SPI output clock SC is also dependent on the programming of the mcu_clk frequency. Recommended programming for 3.579545MHz mcu clock rate, SPI enabled, SC clock phase = `11', master: Value 1.74MHz 0.895MHz 0.447MHz SC Clock Rate F0h F1h F2h Status Register (SSPSTAT, 9402h) MSB ITRA Bit 7 6 5 4 3 2 1 0 IOVR ICOL CSI - LSB - Symbol Function ITRA1 IOVR ICOL CSI 1 Transmission complete interrupt issued. Issued after new data word is available in data-register (slave configuration), or if data-register has been shifted out after write access (master configuration) Overrun interrupt issued. Issued if ITRA is still set from previous transmission and new data arrives (master and slave configuration) Write-collision interrupt issued. Issued if data-register is written during receive (slave configuration) or transmit (master configuration) Not used Always `0', has no effect Not used Not used Not used 1 Note: 1) Flag-bits change state independent of the state of the corresponding interrupt-enable bit of the control register. Revision 3.0, 31-May-06 Page 68 of 123 Data Sheet AS8218 / AS8228 The SPI interrupt status is captured in the SSPSTAT register. Each interrupt status bit can be masked by the SSPCON register, which is OR-ed to a single SPI interrupt request signal (SPI_IRQ). MCU Register SSPSTAT ITRA SSPCON IE IOVR OR SPI_IRQ ICOL IE.ESPI (=IE.3) IETR, IEOV, IECO Figure 11: Block diagram Data Register (SSPBUF, 9403h) The data-register is an 8-bits wide shift-register with parallel load input and parallel output. It is written and read by the MCU in normal operation and by the bootloader during startup phase. parallel SPI_DATAIN from MCU/Bootloader serial out SO 7 6 5 4 3 2 1 0 Bit serial in SI parallel out SPI_DATAOUT to MCU/Bootloader Revision 3.0, 31-May-06 Page 69 of 123 Data Sheet AS8218 / AS8228 8.5 External EEPROM Requirements An external EEPROM with SPI bus serial interface is used for non-volatile program and data storage. The SPI master block that communicates with the EEPROM is specified above. This section explains the requirement for Serial EEPROMs. It shows the most important figures and tables as a reference. For the details please turn to the data sheet of your specifically applied EEPROM. The following minimum requirements must be fulfilled: Pins There must be at least the typical SPI pins like serial data input (EEP_SI), serial data output (EEP_SO) serial clock input (EEP_SC), chip select input (EEP_S_N) Clock Rate The applicable clock rate pin EEP_SC must be 1MHz to allow correct bootloading for maximum mcu_clk = 4MHz. Status Register must look like this: don't care for AS8218 / AS8228 bootloader/SCT Bit 0 must be the WIP bit, indicating that a write operation is in progress. Only this bit is polled during the EEPROM upload, means programming of the EEPROM. The Status register can be accessed via the RDSR instruction. Data Protection The write protection block size is given in the table below: Status Register Bits BP1 0 0 1 1 Protected Block None Upper quarter Upper half Whole memory BP0 0 1 0 1 Array Addresses Protected Example only None 6000h - 7FFFh 4000h - 7FFFh 0000h - 7FFFh Note: The array addresses must be referenced from the data sheet of the specific EEPROM used. Revision 3.0, 31-May-06 Page 70 of 123 Data Sheet AS8218 / AS8228 BP1, BP0 allows the selection of one out of 4 protection schemes. In order to protect against inadvertent programming the user can see these bits. Please note that the protected range of EEPROM cannot be overwritten via an SCT command there anymore. Reprogramming must be done with a dedicated program then. Instruction Set There must be at least 4 instructions with the coding shown in the table for they are deployed by the bootloader to download the user program and by the SCT unit to upload the user program to the EEPROM. Instruction Name READ WRITE Instruction Description Format 03h 02h Read data from memory starting with selected address Write data to memory beginning at selected address. Most EEPROMs allow page writing of pages 16, 32, 64 or even more bytes for faster device programming. Before every page write operation a WREN instruction must be applied - see also bootloading and uploading sequence for details. Write enable EEPROM, enables write operation Read EEPROM Status register, bit 0 = WIP required for AS8218 / AS8228 WREN RDSR 06h 05h SPI Modes These devices can be driven by a microcontroller with its SPI peripheral running in either of the two following modes: - CPOL = 0, CPHA = 0 - CPOL = 1, CPHA = 1 (It is recommended to set CPOL = 1, CPHA = 1 in your program: The build-in bootloader uses this setting as well.) For these two modes, input data is latched in on the rising edge of Serial Clock (SC), and output data is issued on the falling edge of Serial Clock (SC). The recommended mode is shown in Figure 12. The clock polarity SC is `1' when the bus master is in Stand-by mode and not transferring data (idle state): - SC remains at 1 for (CPOL = 1, CPHA = 1) 1 1 EEP_SC(in) EEP_SI(in) EEP_SO(out) Figure 12: SPI modes recommended Revision 3.0, 31-May-06 Page 71 of 123 Data Sheet AS8218 / AS8228 Address Roll Over When the highest address on the EEPROM is reached, e.g. 7FFFh for a 32kB device, then the address counter must roll over to 0000h. Unused Upper Address Bits Unused upper address bits must be ignored in any case. E.g. an 8kB device has a maximum address of 1FFFh must interpret 7FFFh as 1FFFh, ignoring the higher bits. Program Length The program length is stored at the 2 topmost locations, means for a 32kB EEPROM at 7FFEh and 7FFFh. It is possible to use any smaller EEPROM as long as it is guaranteed that a) the upper unused address bits are ignored b) an address roll over is performed after the highest address Timing of AS8218 / AS8228 Boot Sequence Detailed SPI timing generated by the AS8218 / AS8228 - see SPI section. 03h 7Fh FEh 22h 00h 02h 00h 16h 75h 90h Figure 13: Timing diagram The diagram shows the sequence applied to the EEPROM after device reset. On the EEP_SI line you see: 03h (READ) 7Fh (address high) FEh (address low) On the EEP_SO line you see the answer of the EEPROM. In this case the first two values 22h and 00h are forming the program length, means 0022h = 34 bytes are to be fetched and stored to the program memory (P_RAM). The next values are 02h, 00h, 16h (LJMP 0016h) representing the first bytes of the program code. Revision 3.0, 31-May-06 Page 72 of 123 Data Sheet AS8218 / AS8228 Example Pin List Pin Name EEP_S_N Type Input Functionality Chip select, active low Description When this input signal is High, the device is deselected and Serial Data Output (SO) is at high impedance. Unless an internal Write cycle is in progress, the device will be in the Standby mode. Driving Chip Select (S_N) Low enables the device, placing it in the active power mode. This output signal is used to transfer data serially out of the device. Data is shifted out on the falling edge of Serial Clock (SC). This input signal is used to transfer data serially into the device. It receives instructions, addresses and the data to be written. Values are latched on the rising edge of Serial Clock (SC). This input signal provides the timing of the serial interface. Instructions, addresses or data present at Serial Data Input (SI) are latched on the rising edge of Serial Clock (SC). Data on Serial Data Output (SO) changes after the falling edge of Serial Clock (SC). EEP_SO EEP_SI Output Input Serial data output Serial data input EEP_SC Input Serial clock EEP_WP_N 1) Input Write protect, active low The main purpose of this input signal is to freeze the size of the area of memory that is protected against Write instructions (as specified by the values in the BP1 and BP0 bits of the Status register). This pin must be driven either High or Low and must be stable during all write operations. Hold, active low The Hold (HOLD_N) signal is used to pause any serial communications with the device without deselecting the device. During the Hold condition, the Serial Data Output (SO) is high impedance, and Serial Data Input (SI) and Serial Clock (SC) are Don't Care. To start the Hold condition, the device must be selected, with Chip Select (S_N) driven Low. EEP_HOLD_N 1) Input EEP_VCC EEP_VSS Supply Positive supply voltage Supply Negative supply voltage Note: 1) No Write Protect (EEP_WP_N) and Hold (EEP_HOLD_N) pins are available on the AS8218 / AS8228 ICs. These pins must be tied `high' directly at the EEPROM device. Instructions Timings Write Enable (WREN) EEP_S_N(in) EEP_SC(in) EEP_SI(in) EEP_SO(out) Figure 14: Write enable (WREN) sequence Revision 3.0, 31-May-06 Page 73 of 123 Data Sheet AS8218 / AS8228 Read Status Register (RDSR) EEP_S_N(in) EEP_SC(in) EEP_SI(in) EEP_SO(out) Figure 15: Read Status register (RDSR) sequence Read from Memory Array (READ) EEP_S_N(in) EEP_SC(in) EEP_SI(in) EEP_SO(out) Figure 16: Read from memory array (READ) sequence Write to Memory Array (WRITE) EEP_S_N(in) EEP_SC(in) EEP_SI(in) EEP_SO(out) Figure 17: Byte write (WRITE) sequence Revision 3.0, 31-May-06 Page 74 of 123 Data Sheet AS8218 / AS8228 EEP_S_N(in) EEP_SC(in) EEP_SI(in) EEP_S_N(in) EEP_SC(in) EEP_SI(in) Figure 18: Page write (WRITE) sequence Uploading Programs using the SCT In order to allow direct access to the EEPROM via a standard RS232 interface the AS8218 / AS8228 ICs provide a UART to SPI protocol converter. The two system control (SCT) instructions involved are called READ_P (F3h) and WRITE_P (F4h), which may be used to upload user software or user data to the EEPROM. Doing a READ_P allows the verification of the written data, respectively. Example Write EEPROM via UART to SPI Converter: UART RXD TXD SPI EEP_SI EEP_SO WRITE_P F4 WREN 06 x Address 1F F0 F0 x Block Length 00 00 x 02 00 x Data1 21 21 x Data2 42 42 x WAIT Prog.Time RDSR 05 loop until WIP=0 `xxxx xxx0' ACKN FA - Write 02 x 1F x Revision 3.0, 31-May-06 Page 75 of 123 Data Sheet AS8218 / AS8228 WRITE_P F4 1F ADDRESS F0 BLOCK LENGTH 00 02 DATA1 21 DATA2 42 06 03 1F F0 21 42 Read Status Register Figure 19: Timing diagram After having finished the write sequence, the EEPROM goes to programming state for about 5ms to 10ms (depending on the EEPROM type). The AS8218 / AS8228 read out the Status register in a loop until bit0 = WIP (write in progress) goes low. Then the UART transmits the acknowledge instruction FAh. Example Read EEPROM Locations 1FF0 and 1FF1: On EEP_SO the expected 21h and 42h are transmitted. UART RXD TXD SPI EEP_SI EEP_SO READ_P F3 READ 03 x Address 1F 1F x F0 F0 x Block Length 00 00 x 02 00 x Data1 21 00 21 Data2 42 00 42 x ......... don't care - ......... no activity, idle = `1' READ_P F3 1F ADDRESS F0 BLOCK LENGTH 00 02 DATA1 21 10000100s DATA2 42 0 1000010 11001111s 11111000s000001111s 00000000 s 01 000000s (03) (1F) (F0) (21) (42) Figure 20: Timing diagram s ......... stop bit Revision 3.0, 31-May-06 Page 76 of 123 Data Sheet AS8218 / AS8228 8.6 8051 Microcontroller (MCU) The MCU is a derivative of the well-known 8051 microcontroller. The MCU block consists of an 8051 compatible microprocessor core, program memory (P_RAM), data memory (X_RAM), squareroot calculation unit and two UARTs for debugging and communication purposes. The Special Function Registers (SFR) section enfolds the standard blocks like the 16 bit timer (Timer 0), 128 bytes of internal data memory (I_RAM) and a serial interface (UART1). Furthermore, a squareroot block and a second serial interface (UART2) are also provided. Timer 1, Port 0 to 3 and the UART are not implemented exactly the same as in the original 8051. Instead, the bus extension (Port 0, 2 on single chip 8051) provides access to on-chip periphery, which comprises a serial peripheral interface (SPI), a real time clock (RTC), nine general purpose I/Os (MPIO), the LCD driver (LCDD), the DSP block that interfaces to the analog front end and system control registers (SCT). The MCU block is configured as Von Neumann architecture with the program memory (P_RAM) section staring from 0000h and the data memory (X_RAM) and periphery section starting from 8000h up to FFFFh. All 64kB of memory can be accessed with both, the MOVC instruction (for program fetches and data read) and the MOVX instruction (for data read/store). The interrupt controller enfolds 7 internal interrupt sources, for having all necessary peripherals already on chip. Serial EEPROM LC Display Internal Interrupt Sources MCU Interrupt Control 128 bytes I_RAM Timer 0 24kB P_RAM Boot Load SPI LCDD RTC CPU Clock Divider SQRT UART2 1kB X_RAM UART1 SCT MPIO DSP Mclk rxd2 txd2 I/Os AFE RXD TXD Figure 21: MCU block diagram Legend CPU ................ 8051 compatible microcontroller core I_RAM ............. 128 bytes static RAM, range 00h to 7Fh of 8051 X_RAM ............ 1024 bytes static RAM, (extended) memory for data storage P_RAM ............ 24kB static RAM, primarily for program storage, maybe used also for data Timer 0............ 16 bit timer (due to 8051 standard) UART1 ............ serial interface RS232 (due to 8051 standard) with extended baudrate generator Revision 3.0, 31-May-06 Page 77 of 123 Data Sheet AS8218 / AS8228 UART2 ............ serial interface RS232 with extended baudrate generator SQRT .............. square root calculation out of 5 bytes (40 bits) input, 2.5 bytes (20 bits) output SPI.................. serial peripheral interface, used to access an external EEPROM Bootload .......... downloads program data after reset, combined with the SPI LCDD .............. LCD driver block RTC ................ real time clock, time/data may be set via UART1 (SCT) MPIO............... multi-purpose I/O pins, configurable inputs and outputs DSP ................ digital signal processing unit interfaces to analog front end (AFE) AFE................. analog front end, includes amplifiers and A to D converters SCT ................ system control unit, combined with UART1 used for debugging/programming of the device Key Features - 8051 compatible 8 bit oriented microcontroller core 128 bytes of internal data memory (I_RAM) 24kB program memory (P_RAM) 1kB data memory (X_RAM) Von Neumann architecture, shared program and data memory Cycle optimized compared to standard 8051, some instructions are executed in a single clock cycle 128 bytes of SFR range Standard SFRs: Timer 0, UART1 (with 16 baudrate reg.) Specific SFRs: UART2 (with 16 bit baudrate reg.), SQRT block Fully compatible 8051 instruction set including DA, MUL and DIV instruction 7 internal interrupt sources Ports P0, P1, P2, P3 are not implemented P0 and P2 are accessible as registers Register PCON is not implemented No idle mode via PCON Automatic bootload of application program after power-on reset 6 clock cycles per instruction (12 cycles in standard 8051) 1 data pointer DPTR Revision 3.0, 31-May-06 Page 78 of 123 Data Sheet AS8218 / AS8228 Instruction Set The instruction set is fully compatible to the 8051 standard. This allows the use of commonly available software development tools for A51 Assembler, C-Compiler and code simulators. The instructions marked with the note 2) are cycle optimised and execute in a single cycle compared to two cycles in standard 8051 controllers. Hex Code 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F 20 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F Mnemonic NOP AJMP LJMP RR INC INC INC INC INC INC INC INC INC INC INC INC JBC ACALL LCALL RRC DEC DEC DEC DEC DEC DEC DEC DEC DEC DEC DEC DEC JB AJMP RET RL ADD ADD ADD ADD ADD ADD ADD ADD ADD ADD ADD ADD A Operands B/C 1) Hex Code 30 31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F 40 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F 50 51 52 53 54 55 56 57 58 59 5A 5B 5C 5D 5E 5F Mnemonic JNB ACALL RETI RLC ADDC ADDC ADDC ADDC ADDC ADDC ADDC ADDC ADDC ADDC ADDC ADDC JC AJMP ORL ORL ORL ORL ORL ORL ORL ORL ORL ORL ORL ORL ORL ORL JNC ACALL ANL ANL ANL ANL ANL ANL ANL ANL ANL ANL ANL ANL ANL ANL A Operands bit addr, code addr code addr B/C 1) 1/1 code addr code addr A A dir @R0 @R1 R0 R1 R2 R3 R4 R5 R6 R7 bit addr, code code addr code addr A A dir @R0 @R1 R0 R1 R2 R3 R4 R5 R6 R7 bit addr, code code addr 2/2 3/2 1/1 1/1 2/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 3/2 2/2 3/2 1/1 1/1 2/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 3/2 2/2 1/2 1/1 1/1 2/1 2/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 A, #data A, dir A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 3/2 2/2 1/2 1/1 2/1 2/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 2/2 2/2 2/1 3/2 2/1 2/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 2/2 2/2 2/1 3/2 2/1 2/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 A, #data A, dir A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 code addr code addr dir, A dir, #data A, #data A, dir A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 code addr code addr dir, A dir, #data A, #data A, dir A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 Revision 3.0, 31-May-06 Page 79 of 123 Data Sheet AS8218 / AS8228 Hex Code 60 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F 70 71 72 73 74 75 76 77 78 79 7A 7B 7C 7D 7E 7F 80 81 82 83 84 85 86 87 88 89 8A 8B 8C 8D 8E 8F Mnemonic JZ AJMP XRL XRL XRL XRL XRL XRL XRL XRL XRL XRL XRL XRL XRL XRL JNZ ACALL ORL JMP MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV SJMP AJMP ANL MOVC DIV MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV Operands code addr code addr dir, A dir, #data A, #data A, dir A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 code addr code addr C, bit addr @A+DPTR A, #data dir, #data @R0, #data @R1, #data R0, #data R1, #data R2, #data R3, #data R4, #data R5, #data R6, #data R7, #data code addr code addr C, bit addr A, @A+PC AB dir, dir dir, @R0 dir, @R1 dir, R0 dir, R1 dir, R2 dir, R3 dir, R4 dir, R5 dir, R6 dir, R7 B/C 1) Hex Code 90 91 92 93 94 95 96 97 98 99 9A 9B 9C 9D 9E 9F A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 AA AB AC AD AE AF B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 BA BB BC BD BE BF Mnemonic MOV ACALL MOV MOVC SUBB SUBB SUBB SUBB SUBB SUBB SUBB SUBB SUBB SUBB SUBB SUBB ORL AJMP MOV INC MUL n/a MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV ANL ACALL CPL CPL CJNE CJNE CJNE CJNE CJNE CJNE CJNE CJNE CJNE CJNE CJNE CJNE Operands DPTR, #data code addr bit addr, C A, @A+DPTR A, #data A, dir A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 C, /bit addr code addr C, bit addr DPTR AB (reserved) @R0, dir @R1, dir R0, dir R1, dir R2, dir R3, dir R4, dir R5, dir R6, dir R7, dir C, /bit addr code addr bit addr C A, #data, code A, dir, code @R0, #data, code @R1, #data, code R0, #data, code R1, #data, code R2, #data, code R3, #data, code R4, #data, code R5, #data, code R6, #data, code R7, #data, code B/C 1) 2/2 2/2 2/1 3/2 2/1 2/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 2/2 2/2 2/1 2 ) 1/2 2/1 2/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 2/2 2/2 2/1 2 ) 2/2 1/4 3/2 2/1 2/1 2/1 2/1 2/1 2/1 2) 2) 2) 2) 2) 2) 3/2 2/2 2/1 2) 2/2 2/1 2/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 2/1 2 ) 2/2 2/1 1/1 2 ) 1/4 1/1 2/1 2 ) 2/1 2 ) 2/1 2 ) 2/1 2 ) 2/1 2 ) 2/1 2/1 2/1 2/1 2/1 2) 2) 2) 2) 2) 2/1 2 ) 2/2 2/1 1/1 3/2 3/2 3/2 3/2 3/2 3/2 3/2 3/2 3/2 3/2 3/2 3/2 2/1 2 ) 2/1 2 ) 2/1 2 ) 2/1 2 ) Revision 3.0, 31-May-06 Page 80 of 123 Data Sheet AS8218 / AS8228 Hex Code C0 C1 C2 C3 C4 C5 C6 C7 C8 C9 CA CB CC CD CE CF D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 DA DB DC DD DE DF Mnemonic PUSH AJMP CLR CLR SWAP XCH XCH XCH XCH XCH XCH XCH XCH XCH XCH XCH POP ACALL SETB SETB DA DJNZ XCHD XCHD DJNZ DJNZ DJNZ DJNZ DJNZ DJNZ DJNZ DJNZ dir Operands B/C 1) Hex Code E0 E1 E2 E3 E4 E5 E6 E7 E8 E9 EA EB EC ED EE EF F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 FA FB FC FD FE FF Mnemonic MOVX AJMP MOVX MOVX CLR MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV MOVX ACALL MOVX MOVX CPL MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV Operands A, @DPTR code addr A, @R0 A, @R1 A A, dir A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 @DPTR, A code addr @R0, A @R1, A A dir, A @R0, A @R1, A R0, A R1, A R2, A R3, A R4, A R5, A R6, A R7, A B/C 1) 2/1 2) 2/2 2/2 2/2 2/2 1/1 2/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/2 2/2 1/2 1/2 1/1 2/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 code addr bit addr C A A, dir A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 dir code addr bit addr C A dir, code addr A, @R0 A, @R1 R0, code addr R1, code addr R2, code addr R3, code addr R4, code addr R5, code addr R6, code addr R7, code addr 2/2 2/1 1/1 1/1 2/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 2/1 2 ) 2/2 2/1 1/1 1/1 3/2 1/1 1/1 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 dir .............. variable in I_RAM code addr ... address in code memory data ........... immediate data bit addr....... address of a bit in bit-addressable I_RAM Notes: 1) `B' = number of bytes `C' = number of cycles 2) Optimised execution in a single cycle; normally 2 cycles Addressing Modes The MCU comprises all standard 8051 addressing modes. For completeness they are listed here. There are five types. In two byte instructions the destination is specified first, then the source. Mode Register addressing Direct addressing Examples MOV A, R0 MOV R0, A Notes Register R0 in I_RAM one out of 4 banks selected Moves contents of A to R0 Revision 3.0, 31-May-06 Page 81 of 123 Data Sheet AS8218 / AS8228 Mode Register indirect addressing Immediate addressing Index addressing Examples MOV @R0, A MOVX @DPTR, A MOV R0, #data MOVC A, @A+DPTR MOVC A, @A+PC Notes Moves contents of A to location addressed by R0, or by DPTR Moves immediate #data to R0 Moves contents of location addressed by A+DPTR, or A+PC to A. For reading lookup tables, applies to program memory only Interrupt Controller The 8051 core provides 7 interrupt sources: 2 of them are the same as in the standard 8051, the others are tied to specific internal sources. Each interrupt causes the program to jump to the corresponding interrupt vector if the interrupt is enabled in the interrupt enable register (IE). The interrupt priority can be controlled via the interrupt priority register (IP) in order to override the predefined priority, starting with IP.0 as highest. For further information on the interrupt sources refer to the appropriate chapters. Interrupt Enable Register (IE) Each of the interrupt sources can be individually enabled or disabled by setting the corresponding bit in the IE register. This register contains a global enable bit EA. By clearing this bit all interrupts can be disabled at once. IE MSB EA ERTC ES2 ES ESPI EIOX ET0 LSB EDSP Enable bit = 0 disables the interrupt Enable bit = 1 enables the interrupt Interrupt Priority Register (IP) IP MSB PRTC PS2 PS PSPI PIOX PT0 LSB PDSP Priority bit = 1 assigns high priority Priority bit = 0 assigns low priority Interrupt Source Interrupt Vector RTC 0033h UART2 002Bh UART1 0023h SPI 001Bh MPIO 0013h Timer 0 000Bh DSP 0003h Revision 3.0, 31-May-06 Page 82 of 123 Data Sheet AS8218 / AS8228 Symbol EA ERTC ES2 ES ESPI EIOX ET0 EDSP Note: 1) Position 1 IE.7 IE.6 IE.5 1 IE.4 IE.3 IE.2 1 IE.1 IE.0 Function Disables all interrupt when 0. If EA = 1 each interrupt is individually enabled due to its enable bit. RTC real time clock, interrupt enable bit UART2, serial port, interrupt enable bit UART1, serial port, interrupt enable bit SPI serial port, interrupt enable bit MPIO external pin, interrupt enable bit Timer 0, interrupt enable bit DSP data available Priority Lowest Highest Standard 8051 bits Revision 3.0, 31-May-06 Page 83 of 123 Data Sheet AS8218 / AS8228 Interrupt Priorities Each interrupt source can be individually assigned one of two priority levels. A low priority interrupt can always be interrupted by a higher-priority interrupt, but not by another low priority interrupt. A high-priority interrupt cannot be interrupted by any other interrupt source. If the corresponding IP bit is set then this interrupt is serviced first if another interrupt request occurs at the same time where the IP bit is zero. Interrupt on the same priority level are serviced due to the internal polling sequence starting with DSP highest down to RTC lowest. Symbol PRTC PS2 PS PSPI PIOX PT0 PDSP Note: 1) Position IP.7 IP.6 IP.5 1 IP.4 IP.3 IP.2 1 IP.1 IP.0 Function Real time clock, priority bit UART2 serial port, priority bit UART1 serial port, priority bit SPI serial port, priority bit MPIO external pin, priority bit Timer 0, priority bit DSP priority bit Source Flags TSA, STF, A1F, A2F RI, TI RI, TI ITRA in Status 0 / Status 1 TF0 dai, alarm Standard 8051 bits Source PDSP IE Register IP Register IP = 1 IP = 0 Priority Level High Priority Level Low PTO High Priority Interrupt PIOX PSPI Polling Sequence PS PS2 PRTC Low Priority Interrupt Global enable Individual enables Figure 22: Interrupt control system Revision 3.0, 31-May-06 Page 84 of 123 Data Sheet AS8218 / AS8228 Memory Maps The MCU51 is configured as Von Neumann architecture merging program and data range into one 64kB address space. This space is completely accessible via MOVX and partly accessible via MOVC (0000h - 5FFFh). Besides, there is the typical 8051 structure with 128 bytes of internal memory (I_RAM) and the special function registers (SFRs) also in a 128 byte address space. IDATA /PS Memory FFFFh unused 9FFFh C000h unused Direct addressing A000h 9000h 8000h Internal Memory 7Fh 6000h 5FFFh 128 bytes I_RAM 24kB P_RAM 0000h unused 1kB X_RAM 9500h 9400h 9300h 9200h 9100h 9000h SFRs FFh Special Function Registers 80h unused MPIO SPI DSP LCDD RTC SCT 00h Direct addressing Register addressing (4 banks) Bit addressing Register indirect addressing MOVX A, @DPTR MOVX @DPTR, A MOVC A, @A+PC MOVC A, @A+DPTR MOVX @Ri, A MOVXA, @Ri with Ri {R0, R1}, P2 represents upper address bits } only for 0000h - 5FFFh Program Memory (P_RAM) The P_RAM shares address and output data lines with the X_RAM. 24kB out of 64kB addressable memory are used: 0000h - 5FFFh for program storage. Revision 3.0, 31-May-06 Page 85 of 123 Data Sheet AS8218 / AS8228 Data Memory (X_RAM) and Block Interfaces The following table shows the start (and stop) addresses for the X_RAM and the block interfaces. These locations can be accessed with the MOVX instruction. Start Address 8000h 9000h 9100h 9180h 9200h 9300h 9400h 9500h Stop Address 83FFh 9002h 9133h 9181h 9220h 9338h 9403h 951Fh Contents X_RAM SCT Registers RTC Registers WDT Registers LCDD Registers DSP Registers SPI Registers MPIO Registers Detailed Memory map: Address Contents 8000h 9000h 9100h 9104h 9108h 910Ch 9110h 9114h 9118h 911Ch 9130h 9180h 9200h 9204h 9208h 920Ch 9210h 9214h 9218h 921Ch 9220h Seconds/VL Weekdays Cont./Status1 Min.Alarm 1 YearsAlarm 1 Mon. Alarm 2 DivReg B 0 WDTE reg1[7:0] reg1[39:32] reg1[71:64] reg2[7:0] reg2[39:32] reg2[71:64] lcdd_pd ... Address Contents 83FFh 9001h 9101h 9105h 9109h 910Dh 9111h 9115h 9119h 911Dh 9131h 9181h 9201h 9205h 9209h 920Dh 9211h 9215h 9219h 921Dh X_RAM enable signals Minutes Months/Cent. Cont./Status2 Hour Alarm 1 Min.Alarm 2 YearsAlarm 2 DivReg B 1 WDTCLK[1:0] reg1[15:8] reg1[47:40] reg1[79:72] reg2[15:8] reg2[47:40] reg2[79:72] - Address Contents Address Contents 9002h 9102h 9106h 910Ah 910Eh 9112h 9116h 911Ah 911Eh 9132h mcuclkdiv[2:0] Hours Years Sec.Tim.B 0 Day Alarm 1 Hour Alarm 2 DivReg B 2 9003h 9103h 9107h 910Bh 910Fh 9113h 9117h 911Bh 911Fh 9133h Days Sec.Tim.B 1 Mon. Alarm 1 Day Alarm 2 Freq. Trim SCT RTC WDT 9202h 9206h 920Ah 920Eh 9212h 9216h 921Ah 921Eh reg1[23:16] reg1[55:48] reg1[87:80] reg2[23:16] reg2[55:48] reg2[87:80] use_reg 9203h 9207h 920Bh 920Fh 9213h 9217h 921Bh 921Fh reg1[31:24] reg1[63:56] reg1[95:88] reg2[31:24] reg2[63:56] reg2[95:88] selvlcd[2:0] LCDD Revision 3.0, 31-May-06 Page 86 of 123 Data Sheet AS8218 / AS8228 Address Contents 9300h 9304h 9308h 930Ch 9310h 9314h 9318h 931Ch 9320h 9324h 9328h 932Ch 9330h 9334h 9338h 9400h 9500h 9504h 9508h 950Ch 9510h 9514h 9518h 951Ch samptoend [7:0] np[23:16] sos_v[23:16] sos_i1[15:8] sos_i1[47:40] sos_i2[23:16] sos_i2[53:48] pcorr_i1[7:0] cal_v[7:0] cal_i2[7:0] pulselev_i1 2 mconst[3:0] vconst[7:0] Status SSPCON make_irq0 out_mux2 sel_drv1 sel_refp out1 out5 out9 pcnt1 Address Contents 9301h 9305h 9309h 930Dh 9311h 9315h 9319h 931Dh 9321h 9325h 9329h 932Dh 9331h 9335h 9339h 9401h 9501h 9505h 9509h 950Dh 9511h 9515h 9519h 951Dh samptoend [15:8] np[31:24] sos_v[31:24] sos_i1[23:16] sos_i1[53:48] sos_i2[31:24] pcorr_i1[8] cal_v[15:8] cal_i2[15:8] pulselev_i2 0 vconst[13:8] SSPCLKDIV make_irq1 set_en0 sel_pupd0 in0 out2 out6 out10 pcnt2 Address Contents 9302h 9306h 930Ah 930Eh 9312h 9316h 931Ah 931Eh 9322h 9326h 932Ah 932Eh 9332h 9336h 933Ah 9402h 9502h 9506h 950Ah 950Eh 9512h 9516h 951Ah 951Eh np[7:0] sos_v[7:0] sos_v[35:32] sos_i1[31:24] sos_i2[7:0] sos_i2[39:32] pcorr_i2[7:0] cal_i1[7:0] pulselev_i1 0 pulselev_i2 1 nsamp[7:0] Select SSPSTAT out_mux0 set_en1 sel_pupd1 in1 out3 out7 out11 Status0 Address Contents 9303h 9307h 930Bh 930Fh 9313h 9317h 931Bh 931Fh 9323h 9327h 932Bh 932Fh 9333h 9337h 933Bh 9403h 9503h 9507h 950Bh 950Fh 9513h 9517h 951Bh 951Fh np[15:8] sos_v[15:8] sos_i1[7:0] sos_i1[39:32] sos_i2[15:8] sos_i2[47:40] pcorr_i2[8] cal_i1[15:8] pulselev_i1 1 pulselev_i2 2 nsamp[15:8] Gains SSPBUF out_mux1 sel_drv0 sel_in out0 out4 out8 pcnt0 Status1 MPIO SPI DSP Note: Shaded addresses available with the AS8228 only. Revision 3.0, 31-May-06 Page 87 of 123 Data Sheet AS8218 / AS8228 Internal Memory (I_RAM) 128 bytes of I_RAM are provided, which can be accessed via 3 address modes. - All memory 00h to 7Fh is directly addressable. - 00h to 1Fh are register addressable in four banks. Bank switching is done in PSW (Program Status Word). - 20h to 2Fh are bit addressable, which means that each bit of these registers can be set/cleared separately. I_RAM Locations 78h 70h 68h 60h 58h 50h 48h 40h 38h 30h 28h bit 40-47 20h bit 00-07 18h R0 10h R0 08h R0 00h R0 79h 71h 69h 61h 59h 51h 49h 41h 39h 31h 29h bit 48-4F 21h bit 08-0F 19h R1 11h R1 09h R1 01h R1 7Ah 72h 6Ah 62h 5Ah 52h 4Ah 42h 3Ah 32h 2Ah bit 50-57 22h bit 10-17 1Ah R2 12h R2 0Ah R2 02h R2 7Bh 73h 6Bh 63h 5Bh 53h 4Bh 43h 3Bh 33h 2Bh bit 58-5F 23h bit 18-1F 1Bh R3 13h R3 0Bh R3 03h R3 7Ch 74h 6Ch 64h 5Ch 54h 4Ch 44h 3Ch 34h 2Ch bit 60-67 24h bit 20-27 1Ch R4 14h R4 0Ch R4 04h R4 7Dh 75h 6Dh 65h 5Dh 55h 4Dh 45h 3Dh 35h 2Dh bit 68-6F 25h bit 28-2F 1Dh R5 15h R5 0Dh R5 05h R5 7Eh 76h 6Eh 66h 5Eh 56h 4Eh 46h 3Eh 36h 2Eh bit 70-77 26h bit 30-37 1Eh R6 16h R6 0Eh R6 06h R6 7Fh 77h 6Fh 67h 5Fh 57h 4Fh 47h 3Fh 37h 2Fh bit 78-7F 27h bit 38-3F 1Fh R7 17h R7 0Fh R7 07h R7 The first 4 x 8 bytes of the internal memory can be addressed via instructions using the register addressing mode (register bank 0, 1, 2, 3). The following 16 bytes (16 x 8 = 128 bits, address 20h to 2Fh) can be addressed via instructions using the direct-bit addressing mode. The address space from 30h to 7Fh is accessible via the direct addressing mode only. Gray-shaded R0 and R1 registers can be used for register indirect addressing. Special Function Registers (SFR) The following table shows the locations of the Special Function Registers. SFRs in bold style are original 8051 registers. SFRs in italic style are additional registers specific to the AS8218 / AS8228 ICs. Revision 3.0, 31-May-06 Page 88 of 123 Data Sheet AS8218 / AS8228 SFR Locations F8h F0h B E8h SQRTIN0 E0h ACC D8h D0h PSW C8h C0h SCON2 B8h IP B0h SOVR2 A8h IE A0h P2 98h SCON 90h SOVR 88h TCON 80h P0 F9h F1h E9h SQRTIN1 E1h D9h D1h C9h C1h SBUF2 B9h B1h A9h A1h 99h SBUF 91h 89h TMOD 81h SP FAh F2h EAh SQRTIN2 E2h DAh D2h CAh C2h SBAUDL2 BAh B2h AAh A2h 9Ah SBAUDL 92h 8Ah TL0 82h DPL FBh F3h EBh SQRTIN3 E3h DBh D3h CBh C3h SBAUDH2 BBh B3h ABh A3h 9Bh SBAUDH 93h 8Bh 83h DPH FCh F4h ECh SQRTIN4 E4h DCh D4h CCh C4h BCh B4h ACh A4h 9Ch 94h 8Ch TH0 84h FDh F5h EDh SQRTOUT0 E5h DDh D5h CDh C5h BDh B5h ADh A5h 9Dh 95h 8Dh 85h FEh F6h EEh SQRTOUT1 E6h DEh D6h CEh C6h BEh B6h AEh A6h 9Eh 96h 8Eh T0PRE 86h FFh F7h EFh SQRTOUT2 E7h DFh D7h CFh C7h BFh B7h AFh A7h 9Fh 97h 8Fh 87h 128 bytes of SFR address space is available using the direct addressing mode. The following table describes the use of the register bytes: Symbol ACC B PSW SP DPTR DPL DPH P0 P2 IP IE TMOD TCON TH0 TL0 SCON SBUF T0PRE SOVR SBaudL SBaudH SCON2 SBUF2 Register Name Accumulator B Register Program Status Word Stack Pointer Data Pointer 2 Bytes Low Byte High Byte Port 0 Port 2 Interrupt Priority Control Interrupt Enable Control Timer Mode Control Timer Control Timer 0 High Byte Timer 0 Low Byte Serial Control (UART1) Serial Data Buffer (UART1) Timer 0 Prescaler Serial Overflow (UART1) Serial Baudrate Low (UART1) Serial Baudrate High (UART1) UART2 Control UART2 Serial Data Buffer Address Notes E0h F0h D0h 81h 82h 83h 80h A0h B8h A8h 89h 88h 8Ch 8Ah 98h 99h 8Eh 90h 9Ah 9Bh C0h C1h Standard Registers Custom Registers Revision 3.0, 31-May-06 Page 89 of 123 Data Sheet AS8218 / AS8228 Symbol SBaudL2 SBaudH2 SOVR2 SQRTIN0 SQRTIN1 SQRTIN2 SQRTIN3 SQRTIN4 Register Name UART2 Baudrate Low UART2 Baudrate High UART2 Overflow Square Root Input [7:0] Square Root Input [15:8] Square Root Input [23:16] Square Root Input [31:24] Square Root Input [39:32] Address Notes C2h C3h B0h E8h E9h EAh EBh ECh EDh EEh EFh Writing to this location triggers the squareroot calculation SQRTOUT0 Square Root Output [7:0] SQRTOUT1 Square Root Output [15:8] SQRTOUT2 Square Root Output [23:16] Notes: 1) Ports P1 and P3 do not exist. 2) Timer 1 is not implemented (and the related SFRs). 3) Ports P0 and P2 are not connected to pins. P0 and P2 can be used as a register in general. However, P2 can be used for X_RAM access, when `@Ri' is used in the register indirect addressing mode (with Ri being either R0 or R1). In that case P2 will form the higher byte of the X_RAM address. 4) IE/IP: The sources for the interrupts are defined in interrupt controller section. 5) TCON, TMOD, TH0, TLO described in section Timer 0. 6) SCON, SBUF, SBaudL, SBaudH, SOVR are related to UART1 described in the UART section. 7) SCON2, SBUF2, SBaudL2, SBaudH2, SOVR2 are related to UART2 described in the UART2 section. Revision 3.0, 31-May-06 Page 90 of 123 Data Sheet AS8218 / AS8228 Squareroot Block (SQRT) This SQRT block calculates the square root of a 40 bit input value (mapped to 5 eight bit input registers). The output is a 20 bit number which is mapped to 3 eight bit output registers. The calculation starts immediately after the least significant byte has been written (= address E8h). For the square root calculation the Gypsi- or radicand algorithm is used, which produces one bit per clock cycle. Thus after 20 cycles the result is available in the SQRTOUT[2:0] registers. Note: The interrupt signal is not connected to the interrupt controller of the MCU, because the result is available after a defined period of 4 machine cycles. The programmer has to take care for the correct timing. For instance, 4 NOP instructions must be inserted before reading out the result. When writing SQRTIN[39:36] are don't care. When reading SQRTOUT[23:20] those bits equal zero. Data Registers SFR-Address E8h E9h EAh EBh ECh EDh EEh EFh Name SQRTIN0 SQRTIN1 SQRTIN2 SQRTIN3 SQRTIN4 SQRTOUT0 SQRTOUT1 SQRTOUT2 Description Input value[7:0] Input value[15:8] Input value[23:16] Input value[31:24] Input value[39:32] Output value[7:0] Output value[15:8] Output value[19:16] 4 MOV SQRT4, #... 3 2 0 MOV SQRT0, #... 4 cyc MOV A, SQRT2, ... square root calculation start calculation Figure 23: Timing diagram result available During the time of calculation data must not be overridden. As soon as the register SQRT0 is written, the calculation sequence is retriggered and the result is calculated from the latest contents of the 5 input registers. Revision 3.0, 31-May-06 Page 91 of 123 Data Sheet AS8218 / AS8228 Boot Loader (BOOTLOAD) After power-up the boot loader loads the program data from the EEPROM down to the on-chip P_RAM (Note: Parameters or settings stored in the EEPROM will not be loaded by BOOTLOAD, this will be handled by the MCU program.). Only when this is finished the chip can start with its normal operation. (It is also possible to trigger a bootload during normal operation, when for example a new program has been written to the EEPROM (debugging!)) The BOOTLOAD block can be seen as a direct interface between SPI and P_RAM. AS8218/AS8228 MCU B O O T M U X P_RAM boot_sel BOOTLOAD B O O T N O R M A L SPI EEPROM Figure 24: BOOTLOAD block diagram EEPROM Data Organisation 1. 2. 3. Program data are stored beginning at address 0000h. Program data size must not be bigger than 24,576 bytes (0000h - 6000h-1), due to P_RAM size. The length of the program must be stored at the two topmost bytes. The program length is given as number of bytes, expressed as hexadecimal. The lower byte goes to the lower address, the higher byte to the higher address. For a 32kB EEPROM this means: 7FFEh: Length, lower byte, 7FFFh: Length, higher byte. If the length value is bigger than 6000h, the bootloader will just stop after 6000h program data bytes. If the length value is 0000h or FFFFh, no program load will be done. It is also possible to use smaller sized EEPROMs, the length value still has to be stored in the two topmost bytes. The bootloader will always read from the two topmost 32kB addresses, which then are assumed to `rolled down' to the existing two topmost addresses. This adds flexibility to the system configuration. Meter data and system parameters (selects etc.) are stored in the remaining memory space. The allocation of memory space is totally up to the MCU program. Please note that the program data is not protected against overwrites from the MCU program. Case of No Program: In case there is no program stored in the EEPROM (boot loader detects all 0s or all 1s at the program length address) the boot loader writes `SJMP $' (Hex code: 80FEh) to address 0 of the P_RAM. This guarantees the well defined behavior after first power on. 4. 5. 6. 7. 8. 9. Revision 3.0, 31-May-06 Page 92 of 123 Data Sheet AS8218 / AS8228 Watchdog Timer (WDT) A watchdog timer is provided on-chip to automatically initiate a system reset if a `hold-off' signal is not detected within a predefined timeout period, by the watchdog. The watchdog timer consists of a programmable timer driven either by the Mclk (main oscillator output frequency), or the MCU clock (microcontroller unit clock). The watchdog timer timeout period is dependent upon the programming of the WDTCLK register. When the watchdog times out, a reset signal is generated which is OR-ed with the main system reset. Thus a watchdog timer reset is identical to a power on reset. If the watchdog timer function is required, the watchdog is enabled by setting the WDTE register LSB (Bit 0). As soon as this bit is enabled, the program must periodically access the WDTCLK register (either read or write) to prevent the watchdog timer from timeout and thus resetting the device. Register Name WDTE WDTCLK[1:0] x ........Don't care Address 9180h 9181h Reset Value xxxx.xxx0b xxxx.xxx00b Description Enables or disables the watchdog timer function 0: watchdog disabled 1: watchdog enabled A read or write access clears the watchdog timer. Writing bits [1:0] selects the clock source. Watchdog Timer Enable Register (WDTE) MSB - LSB WDTE0 Bit 7 6 5 4 3 2 1 0 Symbol Function Not used Not used Not used Not used Not used Not used Not used WDTE0 Disables and enables the watchdog timer function 0: watchdog disabled 1: watchdog enabled The watchdog timer has a selectable counter length of 18 bit, 20 bit or 22 bit for the Mclk and 18 bits for the mcu_clk. It should be noted that while the Mclk has a fixed frequency, depending on the crystal frequency, the MCU clock is programmable, being divisible by 1 to 128, in binary steps (see MCUCLKDIV Register (`mcu_clk')). The timeout periods below assume the Mclk = 3.579545MHz (fixed crystal frequency). Revision 3.0, 31-May-06 Page 93 of 123 Data Sheet AS8218 / AS8228 Watchdog Timer Clock Register (WDTCLK) MSB WDTCLK1 LSB WDTCLK0 Bit 7 6 5 4 3 2 1 Symbol WDTCLK1 Function Not used Not used Not used Not used Not used Not used Clock Source Watchdog timeout period (Mclk = 3.579545MHz) 0 WDTCLK0 Mclk - default after reset Mclk Mclk Mcu_clk (div=1) Mcuclk (div=128) Timeout Period (ms) 73.2 292.8 1171.2 73.2 9300 Bit1 0 0 1 1 Bit0 0 1 0 1 2 nd UART (UART2) An additional serial interface, UART2 is provided for debugging purposes. UART2 is accessible via two of the multi-purpose I/Os (MPIO). The UART2 is functionally identical to UART1. The SFR addresses are defined as follows: Register Name SCON2 SBUF2 SBAUDL2 SBAUDH2 SOVR2 Address C0h C1h C2h C3h B0h Description Serial port control register - see Serial Interface - UART1 for details. Serial port buffer register - see Serial Interface - UART1 for details. Baudrate reload register - Low address Baudrate reload register - High address `Serial overflow' register, which indicates when data in SBUF has been overwritten before being read. The flag is the LSB with the other 7 bits all being 0. Below is an example how to configure the ports IO7 and IO6 as UART2s txd2 (IO7) and rxd2 (IO6) pins. ;------------------------------------------------------------------------------; Configure UART2 to the pins IO6 and IO7 with the Baudrate of 19200 Baud: ;------------------------------------------------------------------------------; map txd2 = IO7 ; map rxd2 = IO6 ;------------------------------------------------------------------------------xdata mem: OUTMUX1 (9503h) <- 80h ; maps txd2 to IO7 xdata mem: SET_ENO (9505h) <- 80h ; enable output IO7 xdata mem: SEL_PUPDO (9509h) <- 40h ; enable pullup for IO6 xdata mem: SEL_IN (950Bh) <- 05h ; map rxd2 to IO6 idata mem: SBAUDL2 (0C2) <- 11h ; set Baudrate register low idata mem: SBAUDH2 (0C3) <- 00h ; set Baudrate register high idata mem: SCON2 (0C0) <- 50h ; setup UART2 serial port for Rx and Tx. ;------------------------------------------------------------------------------Revision 3.0, 31-May-06 Page 94 of 123 Data Sheet AS8218 / AS8228 ;------------------------------------------------------------------------------; program fragment for enabling uart2 for serial communication. ; ; sfr locations -; SCON2 EQU 0C0h ; Serial 2 Control Register SBUF2 EQU 0C1h ; Serial 2 Port Register SBAUDL2 EQU 0C2h ; Serial 2 Baudload LowByte SBAUDH2 EQU 0C3h ; Serial 2 Baudload HighByte ; ; variables -; BaudrateLO EQU 11 ; Baudrate Value for 19200 baud, BaudrateHI EQU 0 ; mcu_clk = 3.58MHz ; ; memory map for the uart2 configurations -; OUTMUX1 EQU 09503H ; need to be set as 0x80 SET_ENO EQU 09505H ; need to be set as 0x80 SEL_PUPDO EQU 09509H ; need to be set as 0x40 SEL_IN EQU 0950BH ; need to be set as 0x05 ; ; instruction code fragment ; ... MOV IE,#0A0h ; enable serial interrupt UART2 0xA0 MOV DPTR,#OUTMUX1 ; 09503H <- 80h ; maps txd2 to IO7 MOV A,#080h MOVX @DPTR,A MOV DPTR,#SET_ENO ; 09505H <- 80h ; enable output IO7 MOV A,#080h MOVX @DPTR,A MOV DPTR,#SEL_PUPDO ; 09509H <- 40h ; enable pullup for IO6 MOV A,#040h MOVX @DPTR,A MOV DPTR,#SEL_IN ; 0950BH <- 05h ; map rxd2 to IO6 MOV A,#005h MOVX @DPTR,A MOV SBAUDL2,#BaudrateLO ; set Baudrate (16 bits) MOV SBAUDH2,#BaudrateHI MOV SCON2,#050h ; Set up uart2 serial port for Rx and Tx. ; ... ;------------------------------------------------------------------------------- Timer 0 There is only Timer 0 present, Timer 1 is not implemented except for some flags in the TCON register, which are also used for Timer 0. Furthermore, there is no counter mode available as the inputs T1 and INTO of the standard 8051 are not mapped to external pins. The connection of Timer 0 in each of its four operating modes is shown below. Revision 3.0, 31-May-06 Page 95 of 123 Data Sheet AS8218 / AS8228 There are five special function registers (SFR) related to the Timer 0: Register Name TMOD TCON T0PRE TH0 TL0 Address 89h 88h 8Eh 8Ch 8Ah Description Timer mode register Timer control register Timer 0 8 bit prescaler register Timer 0 higher byte Timer 0 lower byte TMOD MSB 0 0 0 0 GATE C/T_N M1 LSB M0 Bit 7 6 5 4 3 2 1 Symbol Function GATE C/T_N M1 Mode select Not used Not used Not used Not used Has no effect on Timer 0 operation can be used as register bit Acts like an enable signal Mode Description 0 1 2 3 13 bit timer (MCS-48 compatible) Same as mode 0 but 16 bit timer Configures Timer 0 as 8 bit autoreload timer. Overflow from TL0 sets TF0 and reloads TL0 with the value of TH0. Two 8 bit timers, TL0 controlled by Timer 0 standard bits, TH0 controlled by Timer 1 control bits but no interrupt Bit1 0 0 1 1 Bit0 0 1 0 1 0 M0 TCON MSB TF1 TR1 TF0 TR0 - LSB - Bit 7 6 5 4 3 2 1 0 Symbol Function TF1 TR1 TF0 TR0 Timer 0 (Mode 3) TH0 overrun flag, generates no interrupt, flag can be polled by software. Timer 0 (Mode 3) TH0 enable flag, TH0 runs if `1' in all other modes the flag has no effect. Timer 0 overrun flag, generates an interrupt. Flag is cleared by hardware when the processor jumps to the interrupt routine Timer 0 run control bit. Timer runs if `1'. Cleared/set by software. Not used Not used Not used Not used Revision 3.0, 31-May-06 Page 96 of 123 Data Sheet AS8218 / AS8228 T0PRE mcu_clk :6 CT_N = 0 :N 1x1x mcu_clk 6N TL0 CT_N = 1 (5 bits) TH0 (8 bits) TF0 Timer 0 Interrupt Control (8bits) *) TR0 Figure 25: Timer 0 Mode 0 and Mode 1 : 13 bit counter *) mcu_clk :6 1 mcu _ clk 6 CT_N = 0 T0PRE :N 1x1x mcu_clk 6N TL0 CT_N = 1 (8 bits) TF0 Timer 0 Interrupt Control TR0 TH0 (8 bits) Reload Figure 26: Timer 0 Mode 2: 8 bit counter mcu_clk :6 1 mcu _ clk 6 CT_N = 0 T0PRE :N 1x1x mcu_clk 6N TR1 TL0 Control TH0 (8 bits) TF1 CT_N = 1 (8 bits) TF0 Timer 0 Interrupt Control TR0 Figure 27: Timer 0 Mode 3: two 8 bit counters T0PRE Unlike the standard 8051 there is a 8-bit prescaler register available for timer 0. Values of 0x00 (default after reset) and 0x01 do not have any effect. For all other values the timer input frequency is divided according to the value (ranging from 2 up to 255). Revision 3.0, 31-May-06 Page 97 of 123 Data Sheet AS8218 / AS8228 8.7 System Control (SCT) The system control is responsible for handling different modes of operation such as normal mode (metering functions) and test mode. The clock generation and reset control are also available in System Control (SCT). Modes of Operation Power off In this mode everything is off including the `System Timing and RTC' block, provided that no battery is connected to VDD_BAT or the battery is discharged. Nothing happens. RTC on, Rest of the Chip off In this mode the `System Timing and RTC' block is supplied by a battery, the RTC is working, but no interrupts are generated. At the moment the battery is inserted, a power-on reset just for the RTC will be generated. The reset will be set to 0 after the first clock edges arrive. Power-up Phase When the power is switched on (for the `rest' of the chip), there is a power-on reset first and the reset is held until the BOOTLOAD block has finished operation. The BOOTLOAD block will load the P_RAM from the external EEPROM. After BOOTLOAD the MCU will start to work. The loaded program will be executed. It is assumed that at the beginning of the program various system parameters are set (sel_i, sel_v, sel_p, creep etc.) No EEPROM programmed, must be loaded from outside If the EEPROM does not contain a program the MCU will run idle mode. It is necessary to write a program to the EEPROM next. Write to EEPROM The EEPROM can directly be written (from outside) using the UART1 interface. The following diagram shows the main blocks involved: SCT UART1 RXD SPI S_N SO SC SI EEPROM Revision 3.0, 31-May-06 Page 98 of 123 Data Sheet AS8218 / AS8228 Note: It would also be possible to write to the EEPROM via the UART2 and the MCU, but then a dedicated MCU program is required to handle the data flow. Transmission Protocol: In order to make the data transfer easier for the system control a defined protocol is used for talking to the UART1, where the length of the data to be written to the EEPROM is specified at the beginning of the transmission. The protocol is as follows: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 ... Write Command (8 bits) Start Address (16 bits) Block Length (16 bits) Data 0 1 2 3 4 5 6 7 (TXD) Acknowledge Notes: 1) When `enable_crc' is set to 0 the UART1 only sends back the acknowledge word (FAh). 2) When `enable_crc' is set to 1 a 16-bit checksum has to be transferred to the UART1 at the end of the data stream. The SCT will calculate the checksum and depending on the result it will send back the acknowledge word (FAh) or the not-acknowledge word (FBh). Read from EEPROM If it is required to read out the EEPROM data this can also be done using the UART1 interface. The following diagram shows the main blocks involved: SCT UART1 TXD RXD SPI S_N SO SC SI EEPROM Again it would also be possible to do this using UART2 and MCU. Transmission Protocol: In order to make the data transfer easier for the system control a defined protocol is used for talking to the UART1, where the length of the data to be read from the EEPROM is specified at the beginning of the transmission. The protocol is as follows: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7 Read Command (8 bits) Start Address (16 bits) Block Length (16 bits) 0 1 2 3 4 5 6 7 ... (TXD) Data Revision 3.0, 31-May-06 Page 99 of 123 Data Sheet AS8218 / AS8228 Note: When `enable_crc' is set to 1 a 16-bit checksum word will be sent after the data stream. It can be used to validate the received data. Reset Chip: Externally triggered BOOTLOAD When a (new) program has been written to the EEPROM it will be necessary to force the chip to load it into the P_RAM. This can be done by generating a chip reset, which triggers a BOOTLOAD sequence. After the related command has been detected by the SCT on the UART1 interface the reset/boot sequence will start. Next the MCU will run the program from the beginning. This command can also be used for a simple reset. The BOOTLOAD is just the extra you get with it. Normal Operation The MCU is working through its program, access to certain blocks/functions may be done via the UART interfaces. For example, it may be required to read data from the EEPROM or from the RTC block. During these operations the MCU is not reset! Program Debugging Program debugging can be done using a so-called monitor program, which may communicate with a PC using the UART2 interface or the UART1 interface in direct access mode. Note: Direct access mode (`dam' register bit) turns off the command interpreter. So if an MCU program does that there is no way out, because after a system reset there is a BOOTLOAD sequence, which loads the same program again. Solution: If pin SI is held at 1 during the startup phase, the `dam' bit will be reset. Read from XDATA Address Mainly for evaluation purposes it will be required to read registers, which are located in the XDATA address space (X_RAM and block interfaces). A dedicated command is reserved for this. The following diagram shows the main blocks involved here: SCT registers DSP registers RTC registers MPIO registers SPI registers X_RAM SCT UART1 RXD TXD Revision 3.0, 31-May-06 Page 100 of 123 Data Sheet AS8218 / AS8228 Transmission Protocol: In order to make the data transfer easier for the system control a defined protocol is used for talking to the UART1, where also the length of the data to be read from the XDATA address space is specified at the beginning of the transmission. It looks like this: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7 Read Command (8 bits) Start Address (16 bits) Block Length (16 bits) 0 1 2 3 4 5 6 7 ... (TXD) Data Note: When `enable_crc' is set to 1 a 16-bit checksum word will be sent after the data stream. It can be used to validate the received data. Write to XDATA Address For evaluation, but also for setting the RTC it will be required to write to a register located in the XDATA address space (X_RAM and block interfaces). Also for this an SCT command is prepared. The following diagram shows the main blocks involved and the data and signal flow: SCT registers DSP registers RTC registers MPIO registers SPI registers X_RAM LCDD registers SCT UART1 RXD Notes: 1) It is guaranteed that the MCU finishes its last (current) command before the XDATA access takes place. 2) In principle it is possible that a value, which has been modified using this write-command, immediately gets overwritten by the MCU. Therefore this command has to be used in an intelligent way. Transmission Protocol: In order to make the data transfer easier for the system control a defined protocol is used for talking to the UART1, where also the length of the data to be written to the XDATA address space is specified at the beginning of the transmission. It looks like this: Revision 3.0, 31-May-06 Page 101 of 123 Data Sheet AS8218 / AS8228 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 ... Write Command (8 bits) Start Address (16 bits) Block Length (16 bits) Data 0 1 2 3 4 5 6 7 (TXD) Acknowledge Notes: 1) When `enable_crc' is set to 0 the UART1 only sends back the acknowledge word (FAh). 2) When `enable_crc' is set to 1 a 16-bit checksum has to be transferred to the UART1 at the end of the data stream. The SCT will calculate the checksum and depending on the result it will send back the acknowledge word (FAh) or the not-acknowledge word (FBh). Flow Diagram of Operational Modes VDD[D|A] off VDD_BAT off insert battery VDD[D|A] off VDD_BAT on power-up (Vmain on) VDD[D|A] on VDD_BAT off: - no clock - chip stays reset power-up (Vmains on) VDD[D|A] on VDD_BAT on Power-on Reset Program execution Command mode disable Command mode enable MCU: Program execution, Command mode active Finished. Program available Finished. No program MCU in idle mode, "loop program" running BOOTLOAD Interrupt from UART Receiving SCT command UART handling f0h f1h f2h f3h f4h f5h Evaluating SCT command Receiving SCT command f6h Reset chip Read Prompt Set Baudrate Read from EEPROM Write to EEPROM Read from XDATA address Write to XDATA address BOOT LOAD 8 bit out: "A" 8 bit out: "L" 8 bit out: "I" 8 bit out: "V" 8 bit out: "E" SBaudH 16 bit address 16 bit address 16 bit address 16 bit address SBaudL 16 bit blocklength 16 bit blocklength 16 bit blocklength 16 bit blocklength 8 bit data out (...) 8 bit data in (...) ACK / NACK 8 bit data out (...) 8 bit data in (...) ACK / NACK Back to MCU Back to MCU Back to MCU Back to MCU Back to MCU Back to MCU Back to MCU Revision 3.0, 31-May-06 Page 102 of 123 Data Sheet AS8218 / AS8228 Note: During `Write/Read EEPROM' or `Write/Read XDATA' the MCU keeps running. The SCT guarantees that there is no collision between MCU and SCT memory accesses. Command Interpreter The command interpreter continuously looks at the UART1 input to detect if a command has been sent, i.e. a specific byte that is defined to initiate a dedicated mode of operation (see flow diagram above). The commands have been specified to lie outside the `normal' ASCII range. All codes not specified within the following table can directly be transferred to the MCU without any interference by the SCT. Command Name SOFT_RESET RD_PROMPT SBAUD Code F0h F1h F2h Description Resets the chip and initiates a BOOTLOAD sequence, then the MCU program is started. The chip sends a specific signature, `ALIVE' which is ASCII coded. This can be used to test the UART1/SCT interface. Makes it possible to set the UART1 baudrate from outside the chip by directly accessing the SFRs `SBaudL' and `SBaudH'. Default setting: 11 (3.5795MHz crystal and 19200 Baud) Enables reading of data from EEPROM. Data can be written to the EEPROM. Data from the XDATA address space can be read. Data can be written to any location in the XDATA address space. READ_P WRITE_P READ_X WRITE_X F3h F4h F5h F6h SCT Registers The system control (SCT) registers provide for the setting of various enables signals and selection of the MCU clock (MCU_CLK) frequency. Register Name Address Reset Value Description enable signals mcuclkdiv[2:0] 9000h 9001h 9002h 000b 000b Not used See table below See table below Enable Signals Register The enable signals register includes power-down signals and other control signals. MSB enable_crc u2clkoff u1clkoff dam sdmi2_pd LSB afe_pd Bit 7 6 Symbol - Function Not used Not used Revision 3.0, 31-May-06 Page 103 of 123 Data Sheet AS8218 / AS8228 Bit 5 Symbol Function enable_crc Enables checksum functionality during read/write accesses to XDATA address space or EEPROM. If enabled, a 16-bit checksum word (see Note below) is sent after the data, which is checked by the SCT (in case of `write') or can be checked by an external component (in case of `read'). 0: checksum disabled 1: checksum enabled u2clkoff u1clkoff dam Switches off the UART2 clock (which is also running at the highest system frequency `mclk'): 0: clock active 1: clock switched off Switches off the UART1 clock (which is running at the highest system frequency `mclk'): 0: clock active 1: clock switched off Select direct access mode for UART1; in case of `dam' input data will no longer be interpreted as commands. 0: direct access mode off 1: dam on Set power-down for current channel 2 (active high) 0: no power-down 1: I2 powered down Set power-down for the entire analog front end (AFE) 0: AFE powered up 1: AFE powered down g(x) = x 16 4 3 2 1 0 sdmi2_pd afe_pd Note: The checksum is calculated using the following formula: +x 12 +x +1 5 MCUCLKDIV Register (`mcu_clk') The mcu clock divider (mcuclkdiv) divides down the main clock (Mclk) which is the output from the low power oscillator. Division of the mcu_clk frequency is provided to enable low power operating modes, for example when the AS8218 / AS8228 ICs are in a battery operating mode, when VDDD is connected to a battery. MSB mcuclkdiv.2 mcuclkdiv.1 LSB mcuclkdiv.0 Bit 7 6 5 4 3 2 Symbol - Function Not used Not used Not used Not used Not used mcuclkdiv.2 These bits set the mcu_clk frequency by dividing down the main clock (Mclk). Bit2 0 0 Bit1 0 0 1 1 0 0 1 1 Bit0 0 1 0 1 0 1 0 1 Division Mclk : 1 Mclk : 2 Mclk : 4 Mclk : 8 Mclk : 16 Mclk : 32 Mclk : 64 Mclk : 128 1 mcuclkdiv.1 0 0 1 0 mcuclkdiv.0 1 1 1 Revision 3.0, 31-May-06 Page 104 of 123 Data Sheet AS8218 / AS8228 8.8 - Serial Interface - UART1 Extended version of the standard 8051 UART1 SBUF and SCON are compatible with standard 8051 Built-in 16 bit baudrate generator (SBAUDH, SBAUDL) Additional SOVR receiver overflow indicator register UART1 is used to communicate externally. UART1 requires only two pins to receive and transmit information. UART1 is compatible to the Serial Interface of the 8051 microcontroller family, with the exception of the baudrate generation. UART1 is functionally identical to UART2. Thus the instructions below are also valid for UART2. UART1 is segmented into three main functional blocks, namely Baudrate, Transmission and Reception, as shown in the block diagram below: Transmission Transmit Unit TB8 EndOfTransmission TxD RI or TI Interrupt Transmit Baudrate Timer SCON SCON Register 16 bit Baudrate Generator Baudrate SBAUDH, SBAUDL Receive Baudrate Timer Start Reception Reception SOVR EndOfReception, RB8 SBUF Receive SBUF Data(0...7) Receive Shifter Detected Bit Receive Shift Enable Receive Control Receive Bit Detector RxD Figure 28: UART1 block diagram There is no direct dependency on osc clock (Mode 0, 3). Instead there is a built-in 16 bit wide baudrate generator for higher flexibility. Revision 3.0, 31-May-06 Page 105 of 123 Data Sheet AS8218 / AS8228 UART is dedicated to the SCT block for writing to and reading from other functional blocks such as RTC, LCDD; besides, it is used for selection of different modes of operation. SFRs of UART1 There are five special function registers dedicated to the UART1. Register Name SCON SBUF SBAUDL SBAUDH SOVR Address Description 98h 99h 9Ah 9Bh 90h Serial port control register Serial port buffer register Baudrate reload register - Low address Baudrate reload register - High address Serial receive buffer overflow register Read/Write from MCU read & write read & write (separate) write only write only read & write, only one bit (=bit0) available SOVR Register Serial receive buffer overflow register. If data is received before it has been read out of SBUF then the bit SOV is set. It can the cleared by software. All other bits of SOVR are 0. SOVR MSB 0 0 0 0 0 0 0 LSB SOV Note: Overflow flag. If `1' then a receiver buffer overflow occurred. The old buffer value has been overwritten by new incoming data. Set by overflow, cleared by MCU. SCON Register The SFR Serial Port Control Register (SCON) is used to configure the UART1 and to check the status of the transmission. SCON MSB SM0 SM1 SM2 REN TB8 RB8 TI LSB RI Revision 3.0, 31-May-06 Page 106 of 123 Data Sheet AS8218 / AS8228 Bit Symbol Function Mode Bit7 Bit6 Mode 0: same as Mode 1, (Mode 0 is not implemented due to 0 0 standard 8051) 0 1 Mode 1: 8-bit UART1, variable Baudrate. - The serial transmission is set to 8 data bits. However up to 10 bits can be sent at port TxD and received at port RxD: start bit (always `0'), eight data bits (LSB first), and a stop bit (always `1'). The value of a received stop bit is Mode select transferred to SCON.RB8 and can be evaluated by the software. flags 1 0 Mode 2: 9-bit UART1, variable Baudrate. - The serial transmission is set to 9 data bits. However up to 11 bits can be sent at port TxD and received at port RxD: start bit (always `0'), nine data bits (LSB first), and a stop bit (always `1'). The value of SCON.TB8 is used for transmitting the ninth data bit (usually as parity bit). The value of the received ninth data bit is transferred to SCON.RB8 and can be evaluated by the software. Mode 3: 9-bit UART1, variable Baudrate. - same as Mode 2. 1 1 Mode Select Flag 2: Enables the multiprocessor communications feature in Mode 2. Mode 0: SM2 is not used. Mode 1: When SM2='1', RI is not set and SBUF is not loaded if the received stop bit is `0'. Mode 2: When SM2='1', RI is not set and SBUF is not loaded if the received ninth data bit is `0'. Please refer also to section Multiprocessor Communications. Receiver Enable Flag. With REN='0' the receiver is disabled, otherwise enabled. REN is to be set and cleared by the software. Value of the ninth data bit to be sent when in mode 2. Value of the ninth data bit received when in mode 2 or value of the stop bit received when in mode 1. Not used in mode 0. Transmit Interrupt Flag. This flag is set by the UART1 at the end of transmitting. In mode 0 flag TI is set at the end of the eighth data bit, in all others modes at the beginning of the stop bit. Flag TI must be cleared by the software. Receive Interrupt Flag. This flag is set by the hardware at the end of receiving. In mode 0 flag RI is set at the end of the eighth data bit, in mode 1 at the middle of the stop bit, and in mode 2 at the middle of the ninth data bit. Flag RI must be cleared by the software. 7 SM0 6 SM1 5 SM2 4 3 2 1 REN TB8 RB8 TI 0 RI Note: 1) Mode Select Flags 0/1: These bits are used to select one of four transmission modes. In all four modes the baudrate is determined by the Baudrate Generator. SBUF Registers The 8-bit register SBUF is the data buffer register which actually consists of two registers for both transmitting and receiving data. Both are accessed by the same address SBUF. A write access to SBUF is redirected into the internal register TransmitSBUF, a read access to SBUF is redirected to the internal register ReceiveSBUF. Remark: The (optional) ninth data bit is defined in SCON.TB8/RB8. SBUF MSB Data 7 Data 6 Data 5 Data 4 Data 3 Data 2 Data 1 LSB Data 0 Revision 3.0, 31-May-06 Page 107 of 123 Data Sheet AS8218 / AS8228 Note: The SBUF register is split up within the UART1 into the internal registers TransmitSBUF (when writing to the SFR) and ReceiveSBUF (when reading from the SFR) A write access to SBUF starts a transmission, according to the selected mode. A write access during an ongoing transmission results in discarding the byte without disturbing the process of transmission. If there is a series of bytes to be transmitted, the software has to wait until the previous byte has been sent (SCON.TI = `1'), before writing to SBUF. The shift sequence (serialization) is handled by means of the internal register TransmitSBUF that holds up to 12 bits (depending on the mode used): hardcoded `1'-bit + start bit + 8 data bits + optional ninth data bit + stop bit. During transmitting the content of TransmitSBUF is shift right, thus transmission is done with LSB first. A read access to SBUF delivers the latest byte received by the UART1. Bit SCON.RI has to be cleared (to `0') by the software after fetching a byte from SBUF, thus enabling the UART1 to receive further bytes. If SCON.RI is not `0' when a new byte is received, the new byte will be discarded (and thus is lost) and SBUF will keep its old value. SBAUDH, SBAUDL Baudrate Reload Registers MSB SBAUDL SBAUDH BR7 BR15 BF6 BR14 BR5 BR13 BR4 BR12 BR3 BR11 BR2 BR10 BR1 BR9 LSB BR0 BR8 Note: The SBAUDL and SBAUDH are merged into a 16 bit reload value: SBAUDL = Baudrate value (7:0) SBAUDH = Baudrate value (15:8) Baudrate Generator Unlike the original 8051 architecture, the UART1 incorporates a built-in baudrate generator. The baudrate is generated by a counter, which is decremented every clock cycle. When reaching the value 0, the counter is automatically reloaded. The reload value is a programmable value stored in the 16 bit register formed by SBAUDH and SBAUDL. A serial bit (during transmit and receive) is further divided into 16 time slices for accurate sampling. Due to the full-duplex operation there is a separate Transmit Baudrate Timer und Receive Baudrate Timer implemented for this task. Baudrate Reload Register The following table shows some selected values to be loaded to the BRReloadRegister (SBaudH + SBaudL) at a given clock frequency that may be used with the AS8218 / AS8228 ICs. The smaller the value, the more difficult it is to meet a demanded baudrate within a given tolerance. If the error is greater than 5% the baudrate is not appropriate for error-free communication. Baudrate [Baud] 110 150 3.00MHz 1704 1249 error [%] 0.0267 0 3.58MHz (3579545Hz) 2033 1491 error [%] 0.0082 -0.0320 4.00MHz 2272 1666 error [%] 0.0120 0.0200 Revision 3.0, 31-May-06 Page 108 of 123 Data Sheet AS8218 / AS8228 Baudrate [Baud] 300 600 1200 2400 4800 9600 19200 38400 57600 76800 115200 3.00MHz 624 312 155 77 38 19 9 4 (2) (1) (1) error [%] 0 0.1597 -0.1603 -0.1603 -0.1603 2.3438 2.3438 2.3438 -8.5069 -22.0703 18.6198 3.58MHz (3579545Hz) 745 372 185 92 46 22 11 5 3 2 1 error [%] 0.0351 0.0350 -0.2337 -0.2337 0.8326 -1.3232 2.8986 2.8986 2.8986 2.8986 2.8986 4.00MHz 832 416 207 103 51 25 12 (6) (3) (2) (1) error [%] -0.0400 0.0799 -0.1603 -0.1603 -0.1603 -0.1603 -0.1603 6.9940 -8.5069 -8.5069 -8.5069 Below there are the formulas for calculating Baudrate and BaudrateReloadRegister, but also the error. You have to divide through 16 because the serial bit is further divided into 16 time slices. Baudrate = ClockFrequency 16 x (1 + BaudrateReloadRegister ) ClockFrequency -1 16 x Baudrate BaudrateReloadRegister = desired _ baudrate - error = ClockFrequency 16 x (1 + Baudrate Re load Re gister ) desired _ baudrate Transmission A write access to register SBUF invokes the transmission of a byte. If there is already an ongoing transmission then the written byte is discarded. At the end of transmission flag SCON.TI is set, indicating the software that the next byte can be written to SBUF. Reception The process of receiving is initiated by setting SCON.REN to `1' and SCON.RI to `0' by software. After reception the UART1 sets SCON.RI to `1' and the data bits can be fetched from SBUF. Each data bit of the serial data stream is probed three times (in the middle of the bit time) to achieve noise immunity. Interrupt Per default the UART1 is operated in the `command mode' (as described in section SCT) and an interrupt is asserted to the MCU except when a command is detected. The UART1 can also be used in the direct access mode (bit dam = `1' in SCT register 9001h). This setting allows the MCU to operate the UART1 as defined in the standard 8051 configuration. Revision 3.0, 31-May-06 Page 109 of 123 Data Sheet AS8218 / AS8228 The UART1 asserts an interrupt whenever flag SCON.RI is `1' or SCON.TI is `1'. These flags are set if a successful receive or transmit operation has taken place. The flags to SCON.RI and SCON.TI must be cleared by software. The MCU program branches to the interrupt routine if the serial interrupt is enabled in the IE register, with IE.4 (= ES) = `1'. Since SCON.RI and SCON.TI are linked together (logic-or), there is a common interrupt service routine for both transmitting and receiving. The interrupt service routine has to decide which event triggered the interrupt request (by querying the flags RI and TI). It is important to clear the flags before leaving the interrupt service routine. Multiprocessor Communications Mode 2 has a special provision for multiprocessor communications. In this mode, a 9 data bit is received and goes into RB8. Then a stop bit follows. The port can be programmed such that when the stop bit is received, the serial port interrupt will be activated only if RB8 = 1. This feature is enabled by setting bit SM2 in SCON. A way to use this feature in multiprocessor systems is as follows: When the master processor wants to transmit a block of data to one of several slaves, it first sends out an address byte which identifies the target slave. An address byte differs from a data byte in that the ninth bit is 1 in an address byte and 0 in a data byte. With SM2 = 1, no slave will be interrupted by a data byte. An address byte, however, will interrupt all slaves, so that each slave can examine the received byte and see if it is being addressed. The addressed slave will clear its SM2 bit and prepare to receive the data bytes that will be coming. The slaves that were not being addressed leave their SM2s set and go on about their business, ignoring the coming data bytes. th Modes The UART1 can be used in two different modes: mode 0 (= mode 1) and mode 2 (= mode 3). The mode selection is due the bits SM0, SM1 in the SCON register. Mode 0 and 1 8 bit UART1 with variable baudrate controlled by the baudrate generator. WrStrobeSFR TransmitEnable TransmitSBUF Transmitting EndOfTransmission TxD TI Start Bit 1 0 0 1 0 0 0 0 Stop Bit 001000010010 000100001001 000010000100 000001000010 000000100001 000000010000 000000001000 000000000100 000000000010 Figure 29: Transmitting in mode 1: here `09h' is sent. The resulting bit stream on the TxD line is: start bit (=`0') + `10010000', for LSB is sent first. The process of transmitting is initiated by writing to SBUF. The byte written to SBUF is held in register TransmitSBUF. The transmission starts with the next 1-pulse on the internal signal TransmitEnable. Output TxD is driven with a start bit (`0'), eight data bits with the LSB first shifted out from TransmitSBUF, and a stop bit (`1'). At Revision 3.0, 31-May-06 Page 110 of 123 Data Sheet AS8218 / AS8228 begin of the stop bit the internal signal EndOfTransmission is activated, causing flag SCON.TI going to high and thus indicating the end of the transmission. ReceiveShiftEnable RxD RB8 RI StartReception Receiving EndOfReception ReceiveShiftRegister ReceiveSBUF 00 011111111 001111111 100111111 110011111 011001111 101100111 110110011 111011001 111101100 F6 Start 0 Bit 0 1 1 0 1 1 1 1 Stop Bit Figure 30: Receiving in mode 1 and mode 2: Here the bit stream `0'+'01101111' is received (see signal ReceivedDataBit), that is: start bit + F6h. The start bit is the first 0-pulse of signal RxD, that is when signal ReceivingStartbit is active. Receiving is only possible when SCON.REN = `1'. The process of receiving is started with a falling edge on RxD (internal signal StartReceiption is activated) and controlled by a 4-bit counter, that means a bit time is divided into 16 time slices. The counter is reset when identifying a falling edge on RxD and is consequently synchronized. The value of RxD is probed three times at the counter stage 6, 7, and 8 (counter range is from 0 to 15). The final value (ReceivedData-Bit) is determined by majority. The multiple probing ensures a more robust serial connection. At counter = 9 the received bit is transferred into the shift register (ReceiveShiftRegister). If the first received bit (stop bit) is not `0', then the process is aborted and the UART1 waits for the next falling edge on RxD. Due to this procedure all data packets with an invalid start bit are automatically discarded. When receiving the stop bit (EndOfReceiption = `1') the following condition is checked: SCON.RI='0' and (SCON.SM2='0' or Received_Stop_Bit='1') If this condition is true, then all eight data bits are transferred to ReceiveSBUF, the stop bit is written to SCON.RB8, and SCON.RI is set to `1'. Otherwise all the received data is discarded and the receiver waits for the next falling edge on RxD. Mode 2 and 3 9 bit UART1 with variable baudrate controlled by the baudrate generator. Mode 2 is very similar to mode 1 except that nine data bits are processed. The subsequent text deals only the differences to mode 1. Mode 3 is the same as Mode 2. The ninth data bit during transmission is taken from SCON.TB8 and is sent after the eight bits from SBUF. When receiving the ninth data bit (EndOfReceiption = `1') the following condition is checked: SCON.RI='0' and (SCON.SM2='0' or Ninth_Data_Bit='1') Revision 3.0, 31-May-06 Page 111 of 123 Data Sheet AS8218 / AS8228 If this condition is true, then all eight data bits are transferred to ReceiveSBUF, the ninth data bit is transferred to SCON.RB8, and SCON.RI is set to `1'. Otherwise all the received data is discarded and the receiver waits for the next falling edge on RxD. Assembler Code The following code fragments demonstrate the programming of the UART1. Adjusting the Baudrate (for all modes) SBL equ 9AH SBH equ 9BH mov SBL,#38 mov SBH,#0 ; Serial BaudrateReload LowByte ; Serial BaudrateReload HighByte ; 9600 baud, 6MHz Using Mode 0 mov mov clr mov wait: jnb TI,wait mov SCON,#10H clr REN wait: jnb RI,wait mov A,SBUF ; wait until data is received ; move received byte into the accu ; wait until data is sent ; mode 0, REN=1 - start reception ; REN=0 SCON,#00H A,#53H TI SBUF,A ; mode 0, REN=0, RI=0, TI=0 ; clear transmit flag ; transmit 53H in mode 0 Transmitting in Mode 0 mov mov clr mov wait: jnb TI,wait ; wait until data is sent SCON,#50H A,#53H TI SBUF,A ; mode 1, REN=1, RI=0, TI=0 ; clear transmit flag ; transmit 53H in mode 1 Receiving in Mode 1 (only bytes with valid stop bit) mov SCON,#70H wait: jnb RI,wait clr RI mov A,SBUF ; wait until data is received ; enable another reception ; move received byte to accu ; mode 1, SM2=1, REN=1, RI=0, TI=0 Transmitting in Mode 2 (ninth data bit as parity bit) mov mov mov mov wait: jnb TI,wait ; wait until data is sent A,#0A4h C,P TB8,C SBUF,A ; ; ; ; move data to accu parity information to carry flag parity information to ninth data bit transmit A4H in mode 2 Interrupt Based Receiving org 0h ; reset vector Revision 3.0, 31-May-06 Page 112 of 123 Data Sheet AS8218 / AS8228 ljmp program_start org 023h ljmp SerialInterrupt org 100 SerialInterrupt: clr RI mov P1, SBUF reti program_start: setb EA setb ES mov SCON,#50H mov SBUF,#2FH clr RI LOOP: jmp LOOP ; endless loop ; serial interrupt vector ; begin of main program ; clear the RI bit (since we know that was ; the bit that caused the interrupt) ; move the received data out to port one ; enable interrupts generally ; enable serial interrupts ; mode 1, REN = 1 ; ensure that RI is cleared Interrupt Based Transmitting org 0h ljmp program_start org 023h ljmp SerialInterrupt org 100 SerialInterrupt: ... ... clr TI reti program_start: setb EA setb ES mov SCON,#40H mov SBUF,#2FH ; reset vector ; serial interrupt vector ; begin of main program ; enable interrupts generally ; enable serial interrupts ; mode 1, REN = 0 Revision 3.0, 31-May-06 Page 113 of 123 Data Sheet AS8218 / AS8228 9. Circuit Diagram N L C22 C21 R13 D5 IC3 VI VO 3.3V GND L1 ZD1 + C23 LCD R1 R2 C1 R3 kWh Vrms Irms 12 RSH R6 C3 R7 C4 AS8228 only R4 R5 C2 LSD23 LSD22 LSD21 LSD20 LSD19 LSD18 LSD17 LSD16 LSD15 LSD14 LSD13 LSD12 LSD11 LSD10 LSD9 50 64 61 63 62 60 59 58 57 56 55 54 53 52 51 49 32 LSD8 48 47 46 45 44 43 42 C5 R8 CT1 R10 R11 C9 C7 R12 R9 C6 VP VN I1P I1N I2P I2N 3.3V VDDA VSSA IO0 IO1 IO2 3.3V C14 IO3 VDD D VSSD IO4 IO5 1 2 3 4 5 6 7 8 9 LSD7 LSD6 LSD5 LSD4 LSD3 LSD2 LSD1 LSD0 LBP3 LBP2 LBP1 LBP0 n.c. n.c. RES_N XOUT XTAL 3.3V D1 C8 C10 C11 IC1 AS8218 / AS8228 41 40 39 38 37 36 35 34 10 11 1 2 13 14 15 20 21 22 23 24 25 26 27 28 29 30 17 18 19 31 16 LOAD VDDD S_N IO9 IO10 SI VSSD IO11 VDD_BAT TXD IO7 IO8 IO6 SO SC RXD C15 3.3V C20 + XIN I/Os Examples only 33 D2 D3 D4 BAT AS8228 only 3.3V 3.3V VDDA C12 + C13 C16 + VDDD C17 VCC 3.3V HOLD IC2 C19 3.3V C18 + Revision 3.0, 31-May-06 Page 114 of 123 Data Sheet AS8218 / AS8228 10. IC1 IC2 IC3 RSH CT1 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 Parts List Value Unit Description AS8218 or AS8228 Metering Integrated Circuits Up to 32kB SPI Bus EEPROM (selectable in binary steps) 3.3 300 V Ohm Voltage regulator LE33CZ Shunt resistor (see `Analog Front End') Current transformer Resistor (see `Analog Front End') 470 470 680 680 680 680 680 680 4.7 680 680 470 100 100 33 33 33 33 33 33 33 33 100 220 100 10 10 1.0 100 Ohm Ohm Ohm Ohm Ohm Ohm Ohm Ohm Ohm Ohm Ohm Ohm nF nF nF nF nF nF nF nF nF nF nF F nF nF nF F nF Resistor (see `Analog Front End') Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor (see `Analog Front End') Resistor Resistor Resistor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Designation Revision 3.0, 31-May-06 Page 115 of 123 Data Sheet AS8218 / AS8228 Designation C18 C19 C20 C21 C22 C23 D1 D2 D3 D4 D5 ZD1 L1 BAT LCD XTAL Value 1.0 100 1.0 10 0.47 470 Unit F nF F nF F F Description Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Diode 1N4148 Diode 1N4148 Diode 1N4148 Diode 1N4148 Diode 1N4004 15 V Zener diode BZV85-C15 Varistor 3.0 V Lithium battery Liquid crystal display 3.579545 MHz Crystal Note: The external components for the programmable multi-purpose I/Os (MPIO) are not included in the above parts list, as they depend on the specific meter functional requirements. Revision 3.0, 31-May-06 Page 116 of 123 Data Sheet AS8218 / AS8228 11. Packaging LQFP64 12. Product Ordering Guide MPIO 9 9 12 12 Device Number AS8218 BLQS AS8218 BLQW AS8228 BLQS AS8228 BLQW LCDD 20 x 4 20 x 4 24 x 4 24 x 4 Temperature -40C to 85C -40C to 85C -40C to 85C -40C to 85C Package LQFP64 LQFP64 LQFP64 LQFP64 Packing Tray in DryPack T & R in DryPack Tray in DryPack T & R in DryPack Revision 3.0, 31-May-06 Page 117 of 123 Data Sheet AS8218 / AS8228 13. Collection of Formulae Shunt resistor for mains current sensing: Rshunt = Vp Ip Where V p is the peak input voltage to the IC at rated conditions and I p the peak Imax value of the meter. CT voltage setting termination resistor for mains current sensing: R VS = Vin(p ) IL 2 Where V in(p) is the peak input voltage to the IC at rated conditions (V mains ; I max ). i.e.: If Gain = 4 then V in(p) must be set at 150mVpeak and I L is the CT RMS secondary current at rated conditions (V mains ; I max ) Voltage divider for the V mains input for the energy calculation: Vmains R1A+R1B R2 Vin R1A + R1B = R2 x ( Vmains - Vin(P ) ) Vin(P ) Where V mains is the peak mains voltage and V in(P) is the is the peak input voltage to the IC at rated conditions. Phase shift value of 1 unit of phase correction relative to the mains frequency: 1unit = 360 x t ovs f f = 360 x mains = 360 x mains tmains fovs fosc / 8 fmains fosc / 8 Phase = # unit x 360 x Revision 3.0, 31-May-06 Page 118 of 123 Data Sheet AS8218 / AS8228 Where fmains is the mains frequency and fOSC is the oscillator frequency. Phase correction factor with a power factor (PF) of less than 1: The meter has been calibrated at PF = 1 and the error is approximately 0 for I cal (calibration current). If the PF is reduced, the effect of phase differences results in an increased error (`phase_error'): First, the related phase shift in degrees can be calculated using the following formula: phase _ error [%] phase _ shift = arc cos 1 + x cos 60 - 60 100 Where the phase_error is the measured error in percentage and cos is the phase angle. For phase_error = 9.2[%] the phase_shift is 3.0. For f osc = 3.579545MHz and f mains = 50Hz one phase correction unit represents 2.41', which is 0.04023. Thus the phase correction factor must be set to 3.0 = 74.57 units 0.04023 = 75 units. The pcorr register has to be set to 4bh. RMS values from the voltage (sos_v) and current (sos_i1 and sos_i2): nsamp 1 nsamp 2 Vi , where Vi2 is the sos_v value nsamp i=1 i =1 Vrms = Irms = 1 nsamp 2 Ii , nsamp i=1 nsamp where i =1 Ii2 is the sos_i value Where nsamp, the number of samples before an update rate of the MDR (meter data register), is selected to achieve coherent sampling. 16-bit calibration values for the voltage (V) and current (I) channels: The ideal values after RMS calculations of voltage (V in of 100mVp at rated conditions) and current and (I in of 30mVp at rated conditions when Gain = 20) are: RMS_V(ideal) = 479 (rms) RMS_I (ideal) = 292,100 (rms) Revision 3.0, 31-May-06 Page 119 of 123 Data Sheet AS8218 / AS8228 Due to non-ideal components a different RMS value is calculated: RMS_I(actual). From this, the required calibration factor is calculated using the following formula: cal _ i = RMS _ I(ideal) RMS _ I(actual) The following formula calculates the actual value to be programmed into the calibration registers (cal_v; cal_i1; cal_i2): cal _ i(reg) = hex(round(cal _ i x 32,768 )) Fast internal pulse rate (PR int ): The Fast Pulse Gen output always has the same relationship with the LED pulse rate, which is defined by mconst. Only if LED is calibrated to a meter constant different from those provided in the mconst table, will the fast internal pulse rate be different. PRint = 204,800 x T arg et Pulse Rate [i / kWh ] mconst Where mconst is the meter constant. 1i = 1,000 x 3,600 [Ws ] PRint Active power calibration (Pulse_lev): The Pulse_lev is specified such that a typical pulse rate of 204,800i/kWh can be achieved. During energy pulse calibration the correct Pulse_lev is determined in order to get the desired pulse rate. The IC default value for Pulse_lev is defined for I max =40A and V mains =230V. Default Pulse_lev: 570,950 The formula for calculating the ideal Pulse_lev is as follows: Pulse _ lev(ideal) = 230 V 40 A x x Pulse _ lev( default ) Vmains Imax The standard or reference meter pulses are counted between two pulses from the meter under test. From the deviation the corrected Pulse_lev may be calculated. Pulse _ lev(corrected) = Pulse _ lev(ideal) x Ni , Na Where Ni is the ideal number of pulses and Na is the actual number of pulses (pcnt register in MPIO). The ideal number of pulses Ni is the ratio between the pulse rates, which is always >1. The formula for Ni is as follows: Revision 3.0, 31-May-06 Page 120 of 123 Data Sheet AS8218 / AS8228 Ni = PR(ref ) LED Pulse Rate(mconst ) Where PR(ref) is the reference meter constant. LED Meter Constant (non-standard): The LED pulses are derived directly from the fast internal pulses (204,800i/kWh) and is specified using the parameter `mconst' of SREG. If the target meter constant is different from one of the selectable (mconst) meter constants, the following formula applies: (Ideal Pulse _ lev x Ni ) Na Ni = Re ference Meter Cons tan t T arg et Pulse Rate Where Ni is calculated using the Target Pulse Rate: NB: For mconst, select a pulse rate close to Target Pulse Rate, so that the Pulse_lev stays within reasonable limits. 14. Terminology Analog front end Current transformer Digital signal processor Electrically erasable programmable read only memory 8051 internal memory kilobyte LCD back-plane driver pin Liquid crystal display Liquid crystal display driver Light-emitting diode Low power divider Low power oscillator Least significant bit LCD segment driver pin Microcontroller unit Meter data register (in DSP block) Programmable multi-purpose input/output Most significant bit Power accumulator for real power Power factor Power low pass filter Program memory Power-supply monitor AFE CT DSP EEPROM I_RAM kB LBPx LCD LCDD LED LP_DIV LP_OSC LSB LSDx MCU MDR MPIO MSB P_ACCU PF PLP P_RAM PSM Revision 3.0, 31-May-06 Page 121 of 123 Data Sheet AS8218 / AS8228 PSW RAM RES_N RMS RTC SCT SDM SFR SQRT SREG SPI UART VREF WDT X_RAM - Program status word Random access memory System reset pin Root mean square Real time clock System control Sigma-delta modulator Special function register Square root block Settings register (in DSP block) Serial peripheral interface Universal asynchronous receiver/transmitter Voltage reference Watchdog timer 8051 external data memory 15. 2.1 3.0 Revision Date 06-Oct-05 31-May-06 Revision Owner DSI DSI Description 16. Copyright Copyright (c) 1997-2006, austriamicrosystems AG, Schloss Premstaetten, 8141 Unterpremstaetten, Austria Europe. Trademarks Registered (R). All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. 17. Disclaimer Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Terms of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are specifically not recommended without additional processing by austriamicrosystems AG for each application. The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However, austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. NO obligation or liability to recipient or any third party shall arise or flow out of austriamicrosystems AG rendering of technical or other services. Revision 3.0, 31-May-06 Page 122 of 123 Data Sheet AS8218 / AS8228 18. Contact austriamicrosystems AG A 8141 Schloss Premstaetten, Austria T. +43 3136 500 0 F. +43 3136 525 01 info@austriamicrosystems.com Revision 3.0, 31-May-06 Page 123 of 123 |
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