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19-1625; Rev 0; 1/00
MAX1280 Evaluation System
General Description
The MAX1280 evaluation system (EV system) is a complete, 8-channel data-acquisition system consisting of a MAX1280 evaluation kit (EV kit) and a Maxim 68HC16MODULE-DIP microcontroller (C) module. The MAX1280 is a high-speed, multichannel, 12-bit dataacquisition system. Windows 95/98(R) software provides a handy user interface to exercise the MAX1280's features. Order the complete EV system (MAX1280EVC16) for a comprehensive evaluation of the MAX1280 using a PC. Order the EV kit (MAX1280EVKIT) if the 68HC16MODULE-DIP module has already been purchased with a previous Maxim EV system, or for custom use in other C-based systems. o Proven PC Board Layout o Convenient On-Board Test Points o Data-Logging Software o Fully Assembled and Tested
Features
Evaluates: MAX1280
Ordering Information
PART MAX1280EVKIT MAX1280EVC16 TEMP. RANGE 0C to +70C 0C to +70C INTERFACE TYPE User-supplied Windows software
EV System Component List
PART MAX1280EVKIT 68HC16 MODULE-DIP QTY 1 1 DESCRIPTION MAX1280 EV kit 68HC16 C module
Note: The MAX1280 software is designed for use with the complete MAX1280EVC16 EV system (includes 68HC16MODULEDIP module together with MAX1280EVKIT). If the MAX1280 evaluation software will not be used, the MAX1280EVKIT board can be purchased by itself, without the C.
EV Kit Software Files
FILE INSTALL.EXE MAX1280.EXE DESCRIPTION Installs the EV kit files on user's computer Application program Software loaded into 68HC16 C
EV Kit Component List
REFERENCE C1-C8, C10 C9 C11, C13 C12, C14 J1 JU1 JU2 R1-R8 R9, R10 TP1 U1 None None None None QTY 9 1 2 2 1 1 1 8 2 1 1 1 1 1 1 DESCRIPTION 0.01F ceramic capacitors 4.7F, 10V tantalum capacitor 0.1F ceramic capacitors 10F, 10V tantalum capacitors 2x20 right-angle socket 2-pin header 3-pin header 300 5% resistors 10 1% resistors 8-pin header Maxim MAX1280BCUP (20-pin TSSOP) PC board, MAX1280 EV kit 3 1/2in software disk, MAX1280 EV kit MAX1280 EV kit data sheet MAX1280 data sheet
KIT1280.C16
Recommended Equipment
Before you begin, gather the following equipment: * Maxim MAX1280EVC16 (contains MAX1280EVKIT board and 68HC16MODULE-DIP) * A small DC power supply, such as a 12VDC, 0.25A plug-in transformer, or a 9V battery * An IBM PC-compatible computer running Windows 95/98 * A spare serial communications port, preferably a 9-pin plug * A serial cable to connect the computer's serial port to the 68HC16MODULE-DIP
Windows 95/98 is a registered trademark of Microsoft Corp.
________________________________________________________________ Maxim Integrated Products
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MAX1280 Evaluation System Evaluates: MAX1280
Connections and Setup
1) Carefully connect the boards by aligning the 40-pin header of the MAX1280 EV kit with the 40-pin connector of the 68HC16MODULE-DIP module. Gently press them together. The two boards should be flush against one another. 2) Ensure that JU1 is closed and JU2 is in the 1-2 position. 3) Connect a 7VDC to 20VDC power source to the C module at the terminal block located next to the on/off switch, along the top edge of the C module. Observe the polarity marked on the board. 4) Connect a cable from the computer's serial port to the C module. If using a 9-pin serial port, use a straight-through, 9-pin female-to-male cable. If the only available serial port uses a 25-pin connector, a standard 25-pin to 9-pin adapter will be required. The EV kit software checks the modem status lines (CTS, DSR, DCD) to confirm that the correct port has been selected. 5) Install the MAX1280 EV kit software on your computer by running the INSTALL.EXE program on the floppy disk. The program files are copied and icons are created for them in the Windows Start menu. 6) Start the MAX1280 program by opening its icon in the Start menu. 7) The program will prompt you to connect the C module and turn its power on. Slide SW1 to the ON position. Select the correct serial port, and click OK. The program will automatically download KIT1280.C16 to the module. 8) Apply an input signal between analog common (COM) and input channel CH0. Observe the readout on the screen. 95/98 software running on an IBM PC interfaces to the EV system board through the computer's serial communications port. See the Recommended Equipment and Connections and Setup sections for setup and operating instructions.
Description of Software
The evaluation software's main window controls the active control word bits, serial clock speed, and sample rate. It displays the voltage and output code for each active channel, as well as some statistics of the input signal. A separate graph window shows the data changing in real time. The update rate is limited to about 10 samples per second due to COM port bandwidth limitations.
Controls
The control word is divided into several fields. To change the active control word, drop down the appropriate field's combo box and select the desired option. If the QSPITM clock is set to STOP, then configuration data will not be sent until the READ button is clicked.
Statistics
The Minimum and Maximum fields show the highest and lowest readings acquired. The Average field shows a running mean based on the equation ai = (k)(xi) + (1 - k)(ai-1). The Clear button resets the statistics. To remove offset errors, first apply 0V to the active input channel, clear statistics, acquire some samples, and then check Tare. This average offset voltage will now be subtracted from all subsequent measurements.
Sampling
Choose the desired sampling rate (QSPI Clock), sampling size (Sample! menu item), click Begin Sampling! (in Sample! pop-up window). Sample size is restricted to a power of 2 to permit FFT processing once the data is saved to a file. After the samples have been collected, the data is automatically uploaded to the host and is graphed. Once displayed, the data can optionally be saved to a file.
Detailed Description
MAX1280 Stand-Alone EV Kit
The MAX1280EVKIT provides a proven PC board layout to evaluate the MAX1280. It must be interfaced to appropriate timing signals for proper operation. Connect +5V to VDD1 and VDD2, and connect the ground return to GND. See the MAX1280 EV kit schematic (Figure 1). Refer to the MAX1280 data sheet for timing requirements.
Saving Graphs to Disk
Data in the real-time graph and in sampled data graphs may be saved to a file. Only the raw output codes are saved, but voltages may be inferred, based on the reference voltage and the maximum code value.
MAX1280 EV System
The MAX1280EVC16 EV system operates from a usersupplied 7VDC to 20VDC power supply. Windows
QSPI is a trademark of Motorola, Inc. 2
Scanning All Channels
To scan through all channels, select SCAN from the INPUT menu.
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MAX1280 Evaluation System Evaluates: MAX1280
Evaluating Shutdown
The evaluation software configures the 68HC16's QSPI submodule to continuously read data from the MAX1280 into the 68HC16. The sample rate is controlled by the QSPI clock. To evaluate power-saving modes, these automatic updates must be stopped. First, set the QSPI clock control to STOP. This reconfigures the 68HC16's QSPI submodule to stop driving the serial clock. Second, in the evaluation software's main window, uncheck the "Read Every...msec" checkbox. Next, choose the desired software power-down control word, and click the Read button to send the new configuration to the MAX1280. Or, if evaluating the hardware shutdown, move jumper JU2 to the 2-3 position. Sense the supply current by measuring the voltage across resistors R9 and R10.
Table 1. Jumper Functions
JUMPER POSITION Closed* JU1 FUNCTION COM is connected to GND. COM is disconnected from GND. All analog inputs, including COM, must still be within the MAX1280's common-mode input range. Operate Shutdown
Open
1-2* JU2 2-3 *Default configuration
Troubleshooting
Problem: No output measurement. System seems to report zero voltage or fails to make a measurement. 1) Check VDD1 and VDD2 supply voltages. 2) Check the 2.5V reference voltage using a DVM. 3) Verify with an oscilloscope that the conversion-start signal is being strobed. 4) Verify that SHDN is being driven high. Problem: Measurements are erratic, unstable; poor accuracy. 1) Check the reference voltage using a DVM. 2) Use an oscilloscope to check for noise. When probing for noise, keep the oscilloscope ground return lead as short as possible, preferably less than 1/2in (10mm).
Reference Voltage
The evaluation software assumes a 2.5V reference voltage, unless otherwise specified. Refer to the MAX1280 data sheet for more information. To override this value, type the new reference voltage into the Vref edit box and click the Set Vref button.
Description of Hardware
U1, the MAX1280, is a high-speed, multichannel, 12-bit data-acquisition system. Resistors R1-R8 and capacitors C1-C8 form single-pole, lowpass anti-aliasing filters with a nominal 3ms time constant and approximately a 50kHz corner frequency. Jumper JU1 connects the analog common (COM) to ground (GND). C10 bypasses the bandgap reference, and C9 bypasses the analog-to-digital converter's (ADC's) voltage reference. When plugged into the 68HC16MODULE, VDD1 and VDD2 are both powered by +5V. See the MAX1280 EV kit schematic (Figure 1) and refer to the MAX1280 data sheet.
Measuring Supply Current
Power-supply current can be monitored by measuring the voltage across resistor R9 (for VDD1) or R10 (VDD2). These resistors are 10 1%, so every 0.001V across R9 represents 100A of supply current.
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MAX1280 Evaluation System Evaluates: MAX1280
VDD1 J1-7 CHO R1 300 C1 0.01F 2 R2 300 C2 0.01F 3 R3 300 C3 0.01F 4 R4 300 C4 0.01F 5 R5 300 C5 0.01F 6 R6 300 C6 0.01F 7 R7 300 C7 0.01F 8 R8 300 C8 0.01F 9
1
1
CHO
VDD1
20 C11 0.1F 19 C13 0.1F 18 TP1-6 J1-37 TP1-1 C14 10F 10V R10 10 1% C12 10F 10V R9 10 1%
VDD1 VDD2 TP1-7 J1-8
CH1
CH1
VDD2
CH2
CH2
SCLK
U1 MAX1280
CH3 CS 17
CH3
TP1-5 J1-31 J1-38
GND
J1-1 J1-2 J1-3 J1-4
CH4
CH4
DIN
16
TP1-4 J1-36
CH5
CH5
SSTRB
15
TP1-3 J1-29
CH6
CH6
DOUT
14
TP1-2 J1-35
CH7
CH7
GND
13
O JU1
2
COM
REFADJ
12 C10 0.01F
REFADJ
10 SHDN
32 1
SHDN
REF
11 C9 4.7F 10V
REF
VDD1 JU2
Figure 1. MAX1280 EV Kit Schematic
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MAX1280 Evaluation System Evaluates: MAX1280
Init: LDAA #$08 ; CS high, clock low by default STAA QPDR LDAA #$0F STAA QPAR ; pins that are assigned to the QSPI LDAA #$0E STAA QDDR ; QSM pins that are outputs LDAA #$80 ; CRCONT STAA CR0 ; send eight-bit control word, and continue... STAA CR2 STAA CR4 ... STAA CRE LDAA #$40 ; (CRBITSE) STAA CR1 ; receive sixteen-bit data field STAA CR3 STAA CR5 ... STAA CRF CLRD ; send zero when receiving data STD TR1 STD TR3 STD TR5 ... STD TRF LDAB #%10001111 ; channel 0, unipolar, single-ended, pd=11 std TR0 ; channel 0 command ldab #$40 ; channel 1 bit mask ord TR0 std TR2 ; channel 1 command ldab #$10 ; channel 2 bit mask ord TR0 std TR4 ; channel 2 command ... ldab #$70 ; channel 7 bit mask ord TR0 std TRE ; channel 7 command CLR SPCR3 ; disable QSPI halt mode interrupt LDD #$8008 ; BITS=16, SPBR=8 (1.049 MHz), CPOL=0, CPHA=0 STD SPCR0 LDD #$0204 ; DSCK, DTL not used STD SPCR1 LDD #$4F00 ; newqp=0, endqp=15, wrap to zero STD SPCR2 ; run QSPI continuously on all channels BSETW SPCR1,#$8000 ; start the QSPI BCLR SPSR,#$80 ; clear SPIF bit ReadLoop: LDD RR1 jsr Process_Channel_0 LDD RR3 jsr Process_Channel_1 LDD RR5 jsr Process_Channel_2 ... LDD RRF jsr Process_Channel_7 jmp ReadLoop
Example 1. Reading All Channels with QSPI
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MAX1280 Evaluation System Evaluates: MAX1280
Init: LDAA #$08 ; CS high, clock low by default STAA QPDR LDAA #$0F STAA QPAR ; pins that are assigned to the QSPI LDAA #$0E STAA QDDR ; QSM pins that are outputs LDAA #$80 ; CRCONT STAA CR0 ; send eight-bit control word, and continue... LDAA #$40 ; (CRBITSE) STAA CR1 ; receive sixteen-bit data field CLRD ; send zero when receiving data STD TR1 LDAB #%10001111 ; channel 0, unipolar, single-ended, pd=11 std TR0 ; channel 0 command CLR SPCR3 ; disable QSPI halt mode interrupt LDD #$8008 ; BITS=16, SPBR=8 (1.049 MHz), CPOL=0, CPHA=0 STD SPCR0 LDD #$0204 ; DSCK, DTL not used STD SPCR1 LDD #$0100 ; newqp=0, endqp=1, no wrap STD SPCR2 ReadLoop: BSETW SPCR1,#$8000 ; start the QSPI BCLR SPSR,#$80 ; clear SPIF bit Idle: BRCLR SPSR,#$80,Idle ; wait util SPIF bit is set LDD RR1 ROLD ROLD ROLD jsr Process_Channel_0 jmp ReadLoop
Example 2. Reading a Single Channel with QSPI
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MAX1280 Evaluation System Evaluates: MAX1280
1.0"
Figure 2. MAX1280 EV Kit Component Placement Guide-- Component Side
1.0"
1.0"
Figure 3. MAX1280 EV Kit PC Board Layout--Component Side
Figure 4. MAX1280 EV Kit PC Board Layout--Solder Side
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MAX1280 Evaluation System Evaluates: MAX1280
NOTES
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