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AUGUST 2003
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XR17L152
3.3V PCI BUS DUAL UART
REV. 1.1.0
GENERAL DESCRIPTION
The XR17L1521 (L152) is a monolithic dual PCI Bus Universal Asynchronous Receiver and Transmitter (UART) in Exar's PCI Bus UART family. The device is designed to meet today's 32-bit PCI Bus and high bandwidth requirements in communication systems. The global interrupt source register provides a complete interrupt status indication for both channels to speed up interrupt parsing. Each UART is independently controlled and has its own 16C550 compatible 5G (Fifth Generation) register set, transmit and receive FIFOs of 64 bytes, fully programmable transmit and receive FIFO trigger levels, transmit and receive FIFO level counters, automatic hardware flow control with programmable hysteresis, automatic software (Xon/Xoff) flow control, automatic half-duplex control output, wireless IrDA (Infrared Data Association) infrared encoder/decoder, 8 multi-purpose definable inputs/outputs, and a 16-bit general purpose timer/counter. NOTE: 1 Covered by U.S. Patents #5,649,122, #5,949,787
FEATURES
APPLICATIONS
* Network Management * Factory Automation and Process Control * Ethernet Network to Serial Ports * Point-of-Sale Systems * Multi serial ports RS-232/RS-422/RS-485 Cards
* High Performance DUART * PCI Bus 2.2 Target Interface Compliance * 3.3 V PCI Bus Compliant up to 33 MHz Clock * 5 Volt Tolerant Serial Inputs * 32-bit PCI Bus Interface with EEPROM Interface * A Global Interrupt Source Register for both UARTs * Data Transfer in Byte, Word and Double-word * Data Read/Write Burst Operation * Each UART is independently controlled with: *16C550 Compatible 5G Register Set *64-byte Transmit and Receive FIFOs *Transmit and Receive FIFO Level Counters *Programmable TX and RX FIFO Trigger Level *Automatic RTS/CTS or DTR/DSR Flow Control *Automatic Xon/Xoff Software Flow Control *Automatic RS485 Half-duplex Control Output
Selectable Turn-around Delay (0 to 15 bit-times)
with
* Eight Multi-Purpose Inputs/outputs * A General Purpose 16-bit Timer/Counter * Sleep Mode with Automatic Wake-up Indicator * Same package and pin-out as XR17C152
XR17D152 (14x14x1.0 mm TQFP)
*Infrared (IrDA 1.0) Data Encoder/Decoder *Programmable Data Rate with Prescaler *Up to 3.125 Mbps Data Rate at 8X Sampling
and
FIGURE 1. BLOCK DIAGRAM
*5V Tolerance for non-PCI Inputs CLK RST# AD[31:0] C/BE[3:0]# FRAME# IRDY# TRDY# DEVSEL# STOP# INTA# IDSEL PERR# SERR# PAR UART Channel 0
64 Byte TX F IFO UA RT Regs TX & R X IR EN DEC
3.3V VCC GND
TX0, RX0, DTR0#, DSR0#, RTS0#, CTS0#, CD0#, RI0#
PCI Local Bus Interface
Device Configuration Registers
BR G
64 Byte RX FIFO
UART Channel 1
UA RT Regs 64 Byte TX F IFO TX & R X BR G IR EN DEC
TX1, RX1, DTR1#, DSR1#, RTS1#, CTS1#, CD1#, RI1#
64 Byte RX FIFO
Configuration Space Registers
EECK EEDI EEDO EECS ENIR EN485#
EEPROM Interface
16-bit Timer/Counter
Multi-purpose . Inputs/Outputs Crystal Osc/Buffer
MPIO0- MPIO7 XTAL1 XTAL2 TMRCK
Exar Corporation 48720 Kato Road, Fremont CA, 94538 * (510) 668-7000 * FAX (510) 668-7017 * www.exar.com
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FIGURE 2. PIN OUT OF THE XR17L152
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
TMRCK
DSR0#
EN485#
DSR1#
DTR0#
DTR1#
RTS0#
CTS0#
RTS1#
CTS1#
MPIO0 52
ENIR
72
75
74
71
70
66
73
69
67
65
64
68
63
61
62
60
59
58
57
55
56
XTAL2 XTAL1 GND TEST# VCC EEDO EEDI EECS EECK INTA# RST# CLK GND VCC AD31 AD30 AD29 AD28 AD27 AD26 AD25 AD24 C/BE3# IDSEL
76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
54
53
51
MPIO1
CD0#
CD1#
GND
VCC
RI0#
RI1#
RX0
NC
RX1
TX0
TX1
NC
50 49 48 47 46 45 44 43 42 41 40
MPIO2 MPIO3 MPIO4 MPIO5 MPIO6 MPIO7 GND VI/O AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7 C/BE0# GND VI/O AD8 AD9 AD10 AD11 AD12 AD13
XR17L152 100-TQFP (14x14x1.0mm)
39 38 37 36 35 34 33 32 31 30 29 28 27 26
VI/O 100
11
21
19
10
12
18
20
22
17
23
24 AD15
FRAME# 13
14
C/BE2#
TRDY# 15
GND
16
STOP#
GND
IRDY#
DEVSEL#
GND
PAR
VI/O
VI/O
AD23
AD22
AD21
AD20
AD18
AD17
PERR#
SERR#
ORDERING INFORMATION
PART NUMBER XR17L152CM XR17L152IM PACKAGE 100-Lead TQFP 100-Lead TQFP OPERATING TEMPERATURE RANGE 0C to +70C -40C to +85C DEVICE STATUS Discontinued. See XR17D152CM for a replacement. Discontinued. See XR17D152IM for a replacement.
2
C/BE1#
AD19
AD16
AD14
25
4
2
8
1
3
5
6
7
9
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
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PIN DESCRIPTIONS
NAME PIN # TYPE DESCRIPTION
PCI LOCAL BUS INTERFACE
RST# 86 I Bus reset input (active low). It resets the PCI local bus configuration space registers, device configuration registers and UART channel registers to the default condition, see Table 18. Bus clock input of up to 33MHz at 3.3V. Address data lines [31:0] (bidirectional).
CLK AD31-AD0
87 90-97, 2-9, 24-31, 35-42 13 98, 12, 21, 34 14
I I/O
FRAME# C/BE3#-C/ BE0# IRDY#
I I
Bus transaction cycle frame (active low). It indicates the beginning and duration of an access. Bus Command/Byte Enable [3:0] (active low). This line is multiplexed for bus Command during the address phase and Byte Enables during the data phase. Initiator Ready (active low). During a write, it indicates that valid data is present on data bus. During a read, it indicates the master is ready to accept data. Target Ready (active low). Target request to stop current transaction (active low). Initialization device select (active high). Device select to the XR17L152 (active low). Device interrupt from XR17L152 (open drain, active low). Parity is even across AD[31:0] and C/BE[3:0]#. (bidirectional, active high). Data Parity error indicator, except for Special Cycle transactions (active low). Optional in bus target application. System error indicator, Address parity or Data parity during Special Cycle transactions (open drain, active low). Optional in bus target application.
I
TRDY# STOP# IDSEL DEVSEL# INTA# PAR PERR# SERR#
15 17 99 16 85 20 18 19
O O I O OD I/O O OD
MODEM OR SERIAL I/O INTERFACE
TX0 RX0 73 66 O I UART channel 0 Transmit Data or infrared transmit data. Normal TXD output idles at logic 1 condition while infrared TXD output idles at a logic 0 condition. UART channel 0 Receive Data or infrared receive data. Normal RXD input idles at logic 1 condition while infrared RXD input idles at a logic 0 condition. In the infrared mode, the polarity of the incoming RXD signal can be selected via FCTR bit-4. If this bit is a logic 0, logic 0 on the RXD input is considered a mark and if this bit is a logic 1, a logic 0 on the RXD input is considered a space. UART channel 0 Request to Send or general purpose output (active low). If this output is not used, leave it unconnected. UART channel 0 Clear to Send or general purpose input (active low). This input should be connected to VCC when not used. UART channel 0 Data Terminal Ready or general purpose output (active low). If this output is not used, leave it unconnected.
RTS0# CTS0# DTR0#
71 67 72
O I O
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PIN DESCRIPTIONS
NAME DSR0# CD0# PIN # 68 69 TYPE I I DESCRIPTION
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
UART channel 0 Data Set Ready or general purpose input (active low). This input should be connected to VCC when not used. UART channel 0 Carrier Detect or general purpose input (active low). This input should be connected to VCC when not used. UART channel 0 Ring Indicator or general purpose input (active low). This input should be connected to VCC when not used. UART channel 1 Transmit Data or infrared transmit data. Normal TXD output idles at logic 1 condition while infrared TXD output idles at a logic 0 condition. UART channel 1 Receive Data or infrared receive data. Normal RXD input idles at logic 1 condition while infrared RXD input idles at a logic 0 condition. In the infrared mode, the polarity of the incoming RXD signal can be selected via FCTR bit-4. If this bit is a logic 0, logic 0 on the RXD input is considered a mark and if this bit is a logic 1, a logic 0 on the RXD input is considered a space. UART channel 1 Request to Send or general purpose output (active low). If this output is not used, leave it unconnected. UART channel 1 Clear to Send or general purpose input (active low). This input should be connected to VCC when not used. UART channel 1 Data Terminal Ready or general purpose output (active low). If this output is not used, leave it unconnected. UART channel 1 Data Set Ready or general purpose input (active low). This input should be connected to VCC when not used. UART channel 1 Carrier Detect or general purpose input (active low). This input should be connected to VCC when not used. UART channel 1 Ring Indicator or general purpose input (active low). This input should be connected to VCC when not used.
RI0# TX1 RX1
70 62 55
I O I
RTS1# CTS1# DTR1# DSR1# CD1# RI1#
60 56 61 57 58 59
O I O I I I
ANCILLARY SIGNALS
MPIO0-MPIO7 52-45 I/O Multi-purpose inputs/outputs 0-7. The function of these pin are defined thru the Configuration Register MPIOSEL, MPIOLVL, MPIOINV, MPIO3T and MPIOINT Serial clock to EEPROM. Pin has a weak internal pull-down resistor and requires an external 10K resistor to operate correctly with the EEPROM. An internal clock of CLK divide by 256 is used for reading the vendor and subvendor ID and model number during power up or reset. However, it can be manually clocked thru the Configuration Register REGB. Chip select to a EEPROM device like 93C46. It is manually selectable thru the Configuration Register REGB. Requires a pull-up 4.7K ohm resister for external sensing of EEPROM during power up. See DAN112 for further details. Write data to EEPROM device. It is manually accessible thru the Configuration Register REGB. The L152 auto-configuration register interface logic uses the 16-bit format. Read data from EEPROM device. It is manually accessible thru the Configuration Register REGB.
EECK
84
O
EECS
83
O
EEDI
82
O
EEDO
81
I
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TYPE I DESCRIPTION Crystal or external clock input of up to data rate of 3.125Mbps at 33MHz 3.3V and 8X sampling. See AC Characterization table. Caution: this input is not 5V tolerant. Crystal or buffered clock output. 16-bit timer/counter external clock input. Global Infrared mode enable (active high). During power up or reset, this pin is sampled and if it is a logic high, both UARTs are set for infrared mode. Also, the infrared mode bit, MCR[6], is set in both channels. Software can override this pin thereafter and enable or disable infrared mode. Global AutoRS485 half-duplex direction control enable (active low). During power up or reset, this pin is sampled and if it is a logic high, both UARTs are set for Auto RS485 Mode. Also, the Auto RS485 bit, FCTR[5], is set in both channels. Software can override this pin thereafter and enable or disable it. Factory Test. Connect to VCC for normal operation. 5V or 3.3V power supply for the core logic. PCI bus I/O power supply. 3.3V ONLY (PCI 2.2 Compliance).
PIN DESCRIPTIONS
NAME XTAL1 PIN # 77
XTAL2 TMRCK ENIR
76 75 74
O I I
EN485#
65
I
TEST# VCC VI/O
79 54, 80 10, 22, 32, 43, 89, 100 1, 11, 23, 33, 44, 53, 78, 88 63, 64
I PWR PWR
GND
PWR
Power supply common, ground.
NC
No Connection.
NOTE: Pin type: I=Input, O=Output, I/O= Input/output, OD=Output Open Drain.
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FUNCTIONAL DESCRIPTION
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
The XR17L152 integrates the functions of 2 enhanced 16550 UARTs with the PCI Local Bus interface and a non-volatile memory interface for PCI bus's plug-and-play auto-configuration, a 16-bit timer/counter, 8 multipurpose inputs/outputs, and an on-chip oscillator. The PCI local bus is a synchronous timing bus where all bus transactions are associated to the bus clock of up to 33 MHz. The L152 supports 32-bit wide read and write data transfer operations including data burst mode through the PCI Local Bus interface. Read and write data operations may be in byte, word or double-word (DWORD) format. The data transfer rate in a DWORD operation is 4 times faster than the single byte operation with 8-bit ISA bus. A single 32-bit interrupt status register provides interrupts status for both UARTs, timer/counter, multipurpose inputs/outputs, and a special sleep wake up indicator. There are three sets of registers in the device. First, the PCI local bus configuration registers for PCI auto configuration. A set of device configuration registers for overall control, 32-bit wide transmit and receive data transfer, and monitoring of the 2 UART channels. Lastly, each UART channel has its own 16550 UART compatible configuration register set for individual channel control, status, and byte wide data transfer. See electrical characteristics table for more details. Each UART has the fifth generation (5G) register set, 64-byte FIFOs, automatic RTS/CTS or DTR/DSR hardware flow control with hysteresis control, automatic Xon/Xoff and special character software flow control, programmable transmit and receive FIFO trigger level, FIFO level counters, infrared encoder and decoder (IrDA ver 1.0), programmable baud rate generator with a prescaler of 1X or 4X, and data rate up to 3 Mbps. The XR17L152 bus timing and drive capability meets the PCI local bus specification revision 2.2 for 3.3 volt 33 MHz operation over the temperature range. For 5V PCI applications, please use the XR17C152 which meets the PCI spec for 5V 33MHz operation over the temperature range. PCI LOCAL BUS INTERFACE This is the host interface and it meets the PCI Local Bus Specification revision 2.2. The PCI local bus operations are synchronous meaning each transaction is associated to the bus clock. The XR17L152 can operate with the bus clock of up to a 33 MHz. Data transfers operation can be formatted in 8-bit, 16-bit, 24-bit or 32-bit wide. With 32-bit data operations, it pushes the data transfer rate on the bus up to 132 MByte/sec. This increases the overall system's communication performance up to 16 times better than the 8-bit ISA bus. See PCI local bus specification revision 2.2 for bus operation details. PCI LOCAL BUS CONFIGURATION SPACE REGISTERS A set of PCI local bus configuration space register is provided. These registers provide the PCI local bus operating system with the card's vendor ID, device ID, sub-vendor ID, product model number, and resources and capabilities. The PCI local bus operating system collects this data from all the cards on the bus during the auto configuration phase that follows immediately after a power up or system reset/reboot. After it has sorted out all devices on the bus, it defines and download the operating conditions to the cards. One of the definitions is the base address loaded into the Base Address Register (BAR) where the card will be operating in the PCI local bus memory space. EEPROM INTERFACE An external 93C46 EEPROM is only used to store the vendor's ID and model number, and the sub-vendor's ID and product model number. This information is only used with the plug-and-play auto configuration of the PCI local bus. These data provide automatic hardware installation onto the PCI bus. The EEPROM interface consists of 4 signals, EEDI, EEDO, EECS, and EECK. The EEPROM is not needed when auto configuration is not required in the application. However, If your design requires non-volatile memory for other purpose. It is possible to store and retrieve data on the EEPROM through a special PCI device configuration register. See application note DAN112 for its programming details.
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1.0 XR17L152 REGISTERS The XR17L152 UART has three different sets of registers as shown in Figure 3. The PCI local bus configuration space registers are for plug-and-play auto-configuration when connecting the device to the PCI bus. This auto-configuration feature makes installation very easy into a PCI system and it is part of the PCI local bus specification. The second register set is the device configuration registers that are accessible directly from the PCI bus for programming general operating conditions of the device and monitoring the status of various functions. These registers are mapped into 1K of the PCI bus memory address space. These functions include both channel UART's interrupt control and status, 16-bit general purpose timer control and status, multipurpose inputs/outputs control and status, sleep mode, soft-reset, and device identification and revision. And lastly, each UART channel has its own set of 5G internal UART configuration registers for its own operation control and status reporting. Both sets of channel registers are embedded inside the device configuration registers space, which provides faster access. The following paragraphs describe all 3 sets of registers in detail. FIGURE 3. THE XR17L152 REGISTER SETS
PCI Local Bus Configuration Space Registers for Plugand-Play Auto Configuration
Device Configuration and UART[1:0] Configuration Registers are mapped on to the Base Address Register (BAR) in a 1Kbyte of memory address space
Vendor and Sub-vendor ID and Product Model Number in External EEPROM
Channel 0 INT, MPIO, TIMER, REG Channel 0
0x0000 0x0080 0x0100 Device Configuration Registers Global Source Interrupt, Multipurpose I/Os, 16-bit Timer/Counter, Sleep, Reset, DVID, DREV
PCI Local Bus Target Interface
0x0200 Channel 1 0x03FF
UART[1:0] Configuration Registers 16550 Compatible and EXAR Enhanced Registers
152REGS
1.1
PCI LOCAL BUS CONFIGURATION SPACE REGISTERS
The PCI local bus configuration space registers are responsible for setting up the device's operating environment in the PCI local bus. The pre-defined operating parameters of the device are read by the PCI bus plug-and-play auto-configuration manager in the operating system. After the PCI bus has collected all data from every device/card on the bus, it defines and downloads the memory mapping information to each device/ card about their individual operation memory address location and conditions. The operating memory mapped address location is downloaded into the Base Address Register (BAR) register, 0x10. The plug-and-play auto configuration feature is only available when an external 93C46 EEPROM is used. The EEPROM contains the device vendor and sub-vendor data required by the auto-configuration setup.
SPACE,
TABLE 1: PCI LOCAL BUS CONFIGURATION SPACE REGISTERS
ADDRESS 0x00 BITS 31:16 15:0 TYPE RWR1 RWR1 DESCRIPTION Device ID (Exar device ID number or from EEPROM) Vendor ID (Exar ID or from EEPROM) assigned by PCISIG RESET VALUE (HEX) 0x0152 0x13A8
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XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
TABLE 1: PCI LOCAL BUS CONFIGURATION SPACE REGISTERS
ADDRESS 0x04 BITS 31 30 29:28 27 26:25 24 23 22:16 15:9,7, 5,4,3,2 8 6 1 0 TYPE RWC RWC RO R-Reset RO RO RO RO RO RWR RWR RWR RO DESCRIPTION Parity error detected. Cleared by writing a logic 1. System error detected. Cleared by writing a logic 1. Unused Target Abort. Set whenever L152 terminates with a target abort. DEVSEL# timing. Unimplemented bus master error reporting bit Fast back to back transactions are supported Reserved Status bits Command bits (reserved) SERR# driver enable. Logic 1=enable driver and 0=disable driver Parity error enable. Logic 1=respond to parity error and 0=ignore Command controls a device's response to mem space accesses: 0=disable mem space accesses, 1=enable mem space accesses Command controls a device's response to I/O space accesses: 0 = disable I/O space accesses 1 = enable I/O space accesses Class Code (Simple 550 Communication Controller). Revision ID (Exar device revision number) BIST (Built-in Self Test) Header Type (a single function device with one BAR) Unimplemented Latency Timer (needed only for bus master) Unimplemented Cache Line Size Memory Base Address Register (BAR) Claims a 1K address space for the memory mapped UARTs Unimplemented Base Address Register (returns zeros) Unimplemented Base Address Register (returns zeros) Unimplemented Base Address Register (returns zeros) Unimplemented Base Address Register (returns zeros) Unimplemented Base Address Register (returns zeros) Reserved Subsystem ID (write from external EEPROM by customer) Subsystem Vendor ID (write from external EEPROM by customer) Expansion ROM Base Address (Unimplemented) RESET VALUE (HEX) 0000
0 00 0 1 000 0000 0x0000 0 0 0 0
0x08
31:8 7:0
RO RO RO RO RO RO RWR RO RO RO RO RO RO RO RWR1 RWR1 RO
0x070002 0x01 0x00 0x00 0x00 0x00 0x00 00 00 00 0000 0000 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000 0x0000 0x0000
0x0C
31:24 23:16 15:8 7:0
0x10
31:10 9:0
0x14 0x18h 0x1C 0x20 0x24 0x28 0x2C
31:0 31:0 31:0 31:0 31:0 31:0 31:16 15:0
0x30
31:0
0x00000000
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RESET VALUE (HEX) 0x00000000 0x00000000 0x00 0x00 0x01 0xXX
TABLE 1: PCI LOCAL BUS CONFIGURATION SPACE REGISTERS
ADDRESS 0x34 0x38 0x3C BITS 31:0 31:0 31:24 23:16 15:8 7:0 TYPE RO RO RO RO RO RWR Reserved (returns zeros) Reserved (returns zeros) Unimplemented MAXLAT Unimplemented MINGNT Interrupt Pin, use INTA#. Interrupt Line. DESCRIPTION
NOTE: RWR1=Read/Write from external EEPROM. RWR=Read/Write from AD[31:0]. RO= Read Only. WO=Write Only.
1.2
Device configuration Register Set
The device configuration registers and a special way to access each of the UART's transmit and receive data FIFOs are accessible directly from the PCI data bus. This provides easy programming of general operating parameters to the L152 UART and for monitoring the status of various functions. The registers occupy 1K of PCI bus memory address space. These addresses are offset onto the basic memory address, a value loaded into the Memory Base Address Register (BAR) in the PCI local bus configuration register set. These registers control or report on both channel UARTs functions that include interrupt control and status, 16-bit general purpose timer control and status, multipurpose inputs/outputs control and status, sleep mode control, softreset control, and device identification and revision, and others. The registers set is mapped into 2 address blocks where each UART channel occupies 512 bytes memory space for its own 16550 compatible configuration registers. The device configuration and control registers are embedded inside the UART channel zero's address space between 0x0080 to 0x0093. All these registers can be accessed in 8, 16, 24 or 32 bit width depending on the starting address given by the host at beginning of the bus cycle. Transmit and receive data may be loaded or unloaded in 8, 16, 24 or 32 bit format to the register's address. Every time a read or write operation is made to the transmit or receive register, its FIFO data pointer is automatically bumped to the next sequential data location either in byte, word or dword. One special case applies to the receive data unloading when reading the receive data together with its LSR register content. The host must read them in 16 or 32 bits format in order to maintain integrity of the data byte with its associated error tags. TABLE 2: XR17L152 DEVICE CONFIGURATION REGISTERS
OFFSET ADDRESS 0x000 - 0x00F 0x010 - 0x07F 0x080 - 0x093 0x094 - 0x0FF 0x100 0x100 0x140 - 0x17F 0x180 - 0x1FF MEMORY SPACE UART channel 0 Regs Reserved DEVICE CONFIG. REGISTERS Reserved UART 0 - Read FIFO UART 0 - Write FIFO Reserved UART 0 - Read FIFO with status Read-Only 16/32 64 bytes of RX FIFO data + LSR (Table 3) Read/Write Read-Only Write-Only 8/16/24/32 8/16/24/32 64 bytes of RX FIFO data 64 bytes of TX FIFO data 8/16/24/32 READ/WRITE (Table 10 & Table 11) DATA WIDTH 8/16/24/32 COMMENT First 8 regs are 16550 compatible
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OFFSET ADDRESS MEMORY SPACE READ/WRITE DATA WIDTH
XR17L152 3.3V PCI BUS DUAL UART
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TABLE 2: XR17L152 DEVICE CONFIGURATION REGISTERS
COMMENT
0x200 - 0x20F 0x210 - 0x2FF 0x300 0x300 0x340 - 0x37F 0x380 - 0x3FF
UART channel 1 Regs Reserved UART 1 - Read FIFO UART 1 - Write FIFO Reserved UART 1 - Read FIFO with status
(Table 10 & Table 11) Read/Write Read-Only Write-Only
8/16/24/32
First 8 regs are 16550 compatible
8/16/24/32 8/16/24/32
64 bytes of RX FIFO data 64 bytes of TX FIFO data
Read-Only
16/32
64 bytes of RX FIFO data + LSR
TABLE 3: DEVICE CONFIGURATION REGISTERS SHOWN IN BYTE ALIGNMENT
ADDRESS [A7:A0] Ox080 Ox081 Ox082 Ox083 REGISTER INT0 [7:0] INT1 [15:8] INT2 [23:16] INT3 [31:24] READ/WRITE COMMENT Read-only Interrupt [1:0], Reserved [7:2] Read-only [5:0], Reserved [7:6] Reserved [7:0] Reserved [7:0] RESET STATE Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00
Ox084 Ox085 Ox086 Ox087
TIMERCNTL TIMER TIMERLSB TIMERMSB
Read/Write Timer Control Reserved Read/Write Timer LSB Read/Write Timer MSB
Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00
Ox088 Ox089 Ox08A Ox08B
8XMODE REGA RESET SLEEP
Read/Write Reserved Write-only Self clear bits after executing Reset [3:0] Read/Write Sleep mode [3:0]
Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00
Ox08C Ox08D Ox08E Ox08F
DREV DVID REGB MPIOINT
Read-only Device revision Read-only Device identification Read/Write Read/Write MPIO interrupt mask
Bits 7-0 = 0x01 Bits 7-0 = 0x22 Bits 7-0 = 0x00 Bits 7-0 = 0x00
Ox090
MPIOLVL
Read/Write MPIO level control
Bits 7-0 = 0x00
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TABLE 3: DEVICE CONFIGURATION REGISTERS SHOWN IN BYTE ALIGNMENT
ADDRESS [A7:A0] Ox091 Ox092 Ox093 REGISTER MPIO3T MPIOINV MPIOSEL READ/WRITE COMMENT Read/Write MPIO output control Read/Write MPIO input polarity select Read/Write MPIO select RESET STATE Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0xFF
TABLE 4: DEVICE CONFIGURATION REGISTERS SHOWN IN DWORD ALIGNMENT
ADDRESS 0x080-083 0x084-087 0x088-08B 0x08C-08F 0x090-093 REGISTER INTERRUPT (read-only) TIMER (read/write) ANCILLARY1 (read/write) ANCILLARY2 (read-only) MPIO (read/write) BYTE 3 [31:24] INT3 TIMERMSB SLEEP MPIOINT MPIOSEL BYTE 2 [23:16] INT2 TIMERLSB RESET REGB MPIOINV BYTE 1 [15:8] INT1 TIMER (reserved) REGA (reserved) DVID MPIO3T BYTE 0 [7:0] INT0 TIMERCNTL 8XMODE DREV MPIOLVL
1.2.1
The Interrupt Status Register
The XR17L152 has a 32-bit wide register [INT0, INT1, INT2 and INT3] to provide interrupt information and supports two interrupt schemes. The first scheme is a 2-bit indicator in INT0 register representing the 2 channels with the first 3 bits representing each channel from 0 to 1. This permits the interrupt routine to quickly vector and serve that UART channel and determine the source(s) in each individual routines. INT0 bit-0 represents the interrupt status for UART channel 0 when its transmitter, receiver, line status, or modem port status requires service. INT0 bit-1 provides interrupt status for channel 1 and bits 2 to 7 are reserved and remain at a logic 0. The second scheme provides detail about the source of the interrupts for each UART channel. All the interrupts are encoded into a 3-bit code per channel. This 3-bit code represents 7 interrupts corresponding to individual UART's transmitter, receiver, line status, modem port status. INT1 and INT2 registers provide the 6-bit interrupt status for both channels. Bits 8, 9 and 10 represents channel 0 and bits 11,12 and 13 represents channel 1. Bits 14 to 31 are reserved and remain at logic zero. Both channels interrupt status are available with a single DWORD read operation. This feature allows the host to quickly vector and serve the interrupts, reducing service interval, hence, reducing host bandwidth requirements. GLOBAL INTERRUPT REGISTER (DWORD)
INT3 [31:24] INT2 [23:16]
[default 0x00-00-00-00]
INT1 [15:8] INT0 [7:0]
Upon power-up or reset, all bits are a logic 0. A special interrupt condition is generated by the L152 upon awakening from sleep after both channels were put to sleep mode earlier. Figure 4 shows the 4-byte interrupt register and its make up. INT0 [7:0] Channel Interrupt Indicator. Each bit gives an indication of the channel that has requested for service. Bit-0 represents channel 0 and bit-1 indicates channel 1. Logic one indicates the channel N [1:0] has requested for service. Bits 2 to 7 are reserved and remain at logic zero The interrupt bit clears after reading the appropriate register of the interrupting channel register, see Interrupt Clearing section.
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The INT0 register provides status for each channel
IN T0 R eg iste r Ind ividua l U A R T C han nel Interru pt S tatu s R s vd R s vd R s vd R s vd R s vd R s vd C h-1 C h-0 B it-7 B it-6 B it-5 B it-4 B it-3 B it-2 B it-1 B it-0
Registers INT3, INT2 and INT1 [32:8] Twenty four bit encoded interrupt indicator. Each channel's interrupt is encoded into 3 bits for receive, transmit, and status. Bit [10:8] represent channel 0 and channel 1 with bits [13:11]. The 3 bit encoding and their priority order are shown below in Table 5. The Timer and MPIO interrupts are for the device and therefore they exist within channel 0 only.
.
FIGURE 4. THE GLOBAL INTERRUPT REGISTER, INT0, INT1, INT2 AND INT3
Interrupt Registers, INT0, INT1, INT2 and INT3
INT3 Register Rsvd Bit N+2 Bit N+1 Bit N Bit N+2 Rsvd Bit N+1 Bit N Bit N+2 Rsvd Bit N+1 Bit N Bit N+2 Rsvd Bit N+1 Bit N Bit N+2 INT2 Register Rsvd Bit N+1 Bit N Bit N+2 Rsvd Bit N+1 Bit N INT1 Register Channel-1 Bit N+2 Bit N+1 Bit N Channel-0 Bit N+2 Bit N+1 Bit N
INT0 Register Rsvd Rsvd Rsvd Rsvd Rsvd Rsvd Ch-1 Ch-0 Bit-3 Bit-2 Bit-1 Bit-0
Bit-7 Bit-6
Bit-5 Bit-4
TABLE 5: UART CHANNEL [1:0] INTERRUPT SOURCE ENCODING
PRIORITY x 1 2 3 4 5 6 7 BIT[N+2] 0 0 0 0 1 1 1 1 BIT[N+1] 0 0 1 1 0 0 1 1 BIT[N] 0 1 0 1 0 1 0 1 None RXRDY and RX Line Status (logic OR of LSR[4:1]) RXRDY Time-out TXRDY, THR or TSR (auto RS485 mode) empty MSR, RTS/CTS or DTR/DSR delta or Xoff/Xon det. or special char. detected Reserved. MPIO pin(s). Available only in channel 0, reserved in channel 1. TIMER Time-out. Available only in channel 0, reserved channel 1. INTERRUPT SOURCE(S)
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TABLE 6: UART CHANNEL [1:0] INTERRUPT CLEARING:
RXRDY is cleared by reading data in the RX FIFO until it falls below the trigger level. RXRDY Time-out interrupt is cleared when the RX FIFO becomes empty. RX Line Status interrupt clears after reading the LSR register. TXRDY interrupt clears after reading ISR register. Modem Status Register interrupt clears after reading MSR register. RTS/CTS or DTR/DSR delta interrupt clears after reading MSR register. Xoff/Xon delta and special character detect interrupt clears after reading the ISR register. TIMER Time-out interrupt clears after reading the TIMERCNTL register that is in the Device Configuration register set. MPIO interrupt clears after reading the MPIOLVL register that is in the Device Configuration register set.
1.2.2
General Purpose 16-bit Timer/Counter. [TIMERMSB, TIMELSB, TIMER, TIMECNTL] (DEFAULT 0XXX-XX-00-00)
A 16-bit down-count timer for general purpose timer or counter. Its clock source may be selected from internal crystal oscillator or externally on pin TMRCK. The timer can be set to be a single-shot for a one-time event or re-triggerable for a continuous interval. An interrupt may be generated in the INT Register when the timer times out. It is controlled through 4 configuration registers [TIMERCNTL, TIMER, TIMELSB, TIMERMSB]. These registers provide start/stop and re-triggerable or one-shot operation. The time-out output of the Timer can be set to generate an interrupt for system or event alarm. FIGURE 5. TIMER/COUNTER CIRCUIT.
T IM E R M S B a n d T IM E R L S B (1 6 -b it V a lu e ) TMRCK OSC. CLOCK T IM E R C N T L [3 ] T IM E R C N T L [1 ] T IM E R C N T L [2 ] T IM E R C N T L [0 ] T IM E R C N T L [4 ] 1 6 -B it T im er/C ou n te r
T im e -o u t 1 0
1 0 C lo ck S e le ct S ta rt/S to p S in g le /R e -trig g e ra b le T im e r In te rru p t E n a b le
T im er In te rru p t, C h-0 IN T = 7
N o In te rru p t
R e -trig g e r 0 1 1 0
M P IO [0 ] M P IO LV L [0 ]
S in g le -sh o t
TABLE 7: TIMER CONTROL REGISTERS
TIMERCNTL [0] TIMERCNLT [1] TIMERCNTL [2] TIMERCNTL [3] TIMERCNTL [4] TIMERCNTL [7:5] Logic zero (default) disables Timer-Counter interrupt and logic one enables the interrupt, reading the TIMERCNTL clears the interrupt. Logic zero (default) stops/pauses the timer and logic one starts/re-starts the timer/counter. Logic zero (default) selects re-trigger timer function and logic one selects one-shot (timer function. Logic zero (default) selects internal and logic one selects external clock to the timer/counter. Routes the Timer-Counter interrupt to MPIO[0] if MPIOSEL[0]=0 for external event control. Reserved (defaults to zero).
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T IM E R C N T L R eg iste r B it-7 B it-6
R svd R svd
B it-5
R svd
B it-4
B it-3
B it-2
B it-1
S ta rt/ S to p
B it-0
IN T E n a b le
M P IO [0 ] C lo ck S in g le / C o n tro l S e le ct R e -trig g e r
TIMER [15:8] (default 0x00) Reserved. TIMERMSB [31:24] and TIMERLSB [23:16] TIMERMSB and TIMERLSB form a 16-bit value. The least-significant bit of the timer is being bit [0] of the TIMERLSB with most-significant-bit being bit-7 in TIMERMSB. Notice that these registers do not hold the current counter value when read. Reading the TIMERCNTL register will clear its interrupt. Default value is zero (timer disabled) upon powerup and reset.
1 6 -B it T im e r/C o u n te r P ro g ra m m a b le R e g iste rs
TIM E RM SB Reg ister B it-15 B it-14 B it-13 B it-1 2 B it-11 B it-10 B it-9 B it-8 B it-7 B it-6 TIM E RLS B Register B it-5 B it-4 B it-3 B it-2 B it-1 B it-0
1.2.3
8XMODE [7:0] (default 0x00)
Each bit selects 8X or 16X sampling rate for that UART channel, bit-0 is channel 0. Logic 0 (default) selects normal 16X sampling with logic one selects 8X sampling rate. Transmit and receive data rates will double by selecting 8X.
8XM O DE Register Individual UART Channel 8X Clock Mode Enable Bit-7 Bit-6 Bit-5 Bit-4 Bit-3 Bit-2 Bit-1 Bit-0
Rsvd Rsvd Rsvd Rsvd Rsvd Rsvd Ch-1 Ch-0
1.2.4 Reserved. 1.2.5
REGA [15:8] (default 0x00) RESET [23:16] - (default 0x00)
The 8-bit Reset register [RESET] provides the software with the ability to reset the UART(s) when there is a need. Each bit is self-resetting after it is written a logic 1 to perform a reset to that channel. All registers in that channel will be reset to the default condition, see Table 18 for details. Bit-0 =1 resets UART channel 0 while bit1=1 resets channel 1.
RESET Register Individual UART Channel Reset Enable Bit-7 Bit-6 Bit-5 Bit-4 Bit-3 Bit-2 Bit-1 Bit-0
Rsvd Rsvd Rsvd Rsvd Rsvd Rsvd Ch-1 Ch-0
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1.2.6
SLEEP [31:24] - (default 0x00)
The first two bits of the Sleep register enables each UART channel separately to enter Sleep mode. The upper bits 2 to 7 are reserved. Sleep mode reduces power consumption when the system needs to put the UART(s) to idle. The UART enters Sleep mode when there is no interrupt pending. When both UARTs are put to sleep, the on-chip oscillator shuts off to further conserve power. In this case, the XR17L152 is awakened on any of the channels by a receive data byte or a change on the serial port. The UART is ready after 32 crystal clocks to ensure full functionality. Also, a special interrupt is generated with an indication of no pending interrupt. Logic 0 (default) disables sleep mode and logic 1 enables it.
SLEEP Register Individual UART Channel Sleep Enable Bit-7 Bit-6 Bit-5 Bit-4 Bit-3 Bit-2 Bit-1 Bit-0 Rsvd Rsvd Rsvd Rsvd Rsvd Rsvd Ch-1 Ch-0
1.2.7
Device Identification and Revision
There are 2 internal registers that provide device identification and revision, DVID and DREV registers. The 8bit content in the DVID register provides device identification. A return value of 0x22 from this register indicates the device is an XR17C152 or an XR17L152. The DREV register returns an 8-bit value of 0x01 for revision A with 0x02 equals to revision B and so forth. This information is very useful to the software driver for identifying which device it is communicating with and to keep up with revision changes. DVID [15:8] Device identification for the type of UART. The upper nibble indicates it is an XR17Cxxx or XR17Lxxx series device with lower nibble indicating the number of channels. Examples: XR17C158 = 0x28 XR17C154 or XR17L154 = 0x24 XR17C152 or XR17L152 = 0x22 DREV [7:0] Revision number of the XR17L152. A 0x01 represents "revision-A" with 0x02 for rev-B and so forth. REGB [23:16] (default 0x00) REGB register provides a control for simultaneous write to both UARTs configuration register or individually. This is very useful for device initialization in the power up and reset routines. Also, the register provides a facility to interface to the non-volatile memory device such as a 93C46 EEPROM. In embedded applications, the user can use this facility to store proprietary data. 1.2.8 REGB Register
Logic 0 (default) write to each UART configuration registers individually. Logic 1 enables simultaneous write to both UARTs configuration register. REGB[19:17] REGB[20] (Write-Only) REGB[21] (Write-Only) REGB[22] (Write-Only) REGB[23] (Read-Only) Reserved. Control the EECK, clock, output (pin 116) on the EEPROM interface. Control the EECS, chips select, output (pin 115) to the EEPROM device. EEDI (pin 114) data input. Write data to the EEPROM device. EEDO (pin 113) data output. Read data from the EEPROM device.
REGB[16] (Read/Write)
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1.2.9 Multi-Purpose Inputs and Outputs
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REV. 1.1.0
The L152 provides 8 multi-purpose inputs/outputs [MPIO7:0] for general use. Each pin can be programmed to be an input or output function. The input logic state can be set for normal or inverted level, and optionally set to generate an interrupt. The outputs can be set to be normal logic 1 or 0 state, or three-state. Their functions and definitions are programmed through 5 registers: MPIOINT, MPIOLVL, MPIO3T, MPIOINV and MPIOSEL. If all 8 pins are set for inputs, all 8 interrupts would be or'ed together. The Or'ed interrupt is reported in the channel 0 UART interrupt status, see Interrupt Status Register. The pins may also be programmed to be outputs and to the three-state condition for signal sharing. 1.2.10 MPIO REGISTER Bit 7 represents MPIO7 pin and bit 0 represents MPIO0 pin. There are 5 registers that select, control and monitor the 8 multipurpose inputs and output pins. Figure 6 shows the internal circuitry. FIGURE 6. MULTIPURPOSE INPUT/OUTPUT INTERNAL CIRCUIT
MPIOINT [7:0]
INT
AND
Rising Edge Detection
AND
1 MPIOLVL [7:0]
Read Input Level
MPIO Pin [7:0] 0
MPIOINV [7:0]
(Input Inversion Enable =1)
MPIOLVL [7:0]
(Output Level)
MPIO3T [7:0]
(3-state Enable =1) OR
MPIOSEL [7:0]
(Select Input=1, Output=0 ) MPIOCKT
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MPIOINT [7:0] (default 0x00) Enable multipurpose input pin interrupt. If the pin is selected by MPIOSEL as input then bit-0 enables input pin 0 for interrupt, and bit-7 enables input pin 7. No interrupt is enable if the pin is selected to be an output. The interrupt is edge sensing and determined by MPIOINV and MPIOLVL registers. The MPIO interrupt clears after a read to register MPIOLVL. The combination of MPIOLVL and MPIOINV determines the interrupt being active low or active high, it's level trigger. Logic 0 (default) disables the pin's interrupt and logic 1 enables it.
M PIO IN T R egister M ultipu rpo se Inp ut/O u tpu t In terrup t E n ab le B it-7 B it-6 B it-5 B it-4 B it-3 B it-2 B it-1 B it-0
M P IO 7 M P IO 6 M P IO 5 M P IO 4 M P IO 3 M P IO 2 M P IO 1 M P IO 0
MPIOLVL [7:0] (default 0x00) Output pin level control and input level status. The status of the input pin(s) is read on this register and output pins are controlled on this register. A logic 0 (default) sets the output to low and a logic 1 sets the output pin to high. The MPIO interrupt will clear upon reading this register.
M PIO L VL R egister M ultipurpose O utput Level C ontrol B it-7 B it-6 B it-5 B it-4 B it-3 B it-2 B it-1 B it-0
M P IO 7 M P IO 6 M P IO 5 M P IO 4 M P IO 3 M P IO 2 M P IO 1 M P IO 0
MPIO3T [7:0] (default 0x00) Output pin three-state control. A logic 0 (default) sets the output to active level per register MPIOBIT settling, a logic 1 sets the output pin to tri-state.
M PIO 3T Register M ultipurpose O utput 3-state E n able B it-7 B it-6 B it-5 B it-4 B it-3 B it-2 B it-1 B it-0
M P IO 7 M P IO 6 M P IO 5 M P IO 4 M P IO 3 M P IO 2 M P IO 1 M P IO 0
MPIOINV [7:0] (default 0x00) Input inversion control. A logic 0 (default) does not invert the input pin logic. A logic 1 inverts the input logic level.
M PIO INV Register M ultipurpose Input S ignal Inversion E nable B it-7 B it-6 B it-5 B it-4 B it-3 B it-2 B it-1 B it-0
M P IO 7 M P IO 6 M P IO 5 M P IO 4 M P IO 3 M P IO 2 M P IO 1 M P IO 0
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MPIOSEL [7:0] (default 0xFF)
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REV. 1.1.0
Multipurpose input/output pin select. This register defines the functions of the pins. A logic 1 (default) defines the pin for input and a logic "0" for output.
MPIOSEL Register Multipurpose Input/Output Selection Bit-7 Bit-6 Bit-5 Bit-4 Bit-3 Bit-2 Bit-1 Bit-0
MPIO7 MPIO6 MPIO5 MPIO4 MPIO3 MPIO2 MPIO1 MPIO0
2.0 CRYSTAL OSCILLATOR / BUFFER The L152 includes an on-chip oscillator (XTAL1 and XTAL2). The crystal oscillator provides the system clock to the Baud Rate Generators (BRG) in each of the 2 UARTs, the 16-bit general purpose timer/counter and internal logics. XTAL1 is the input to the oscillator or external clock buffer input with XTAL2 pin being the output. See Programmable Baud Rate Generator in the UART section for programming details. The on-chip oscillator is designed to use an industry standard microprocessor crystal (parallel resonant with 10-22 pF capacitance load, 100ppm) connected externally between the XTAL1 and XTAL2 pins (see Figure 7). Alternatively, an external clock can be connected to the XTAL1 pin to clock the internal 2 baud rate generators for standard or custom rates. Typically, the oscillator connections are shown in Figure 7. For further reading on oscillator circuit please see application note DAN108 on EXAR's web site. FIGURE 7. TYPICAL OSCILLATOR CONNECTIONS
R =3 0 0 K to 4 00 K
X T A L1
1 4 .7 45 6 MHz
X T A L2
C1 2 2 -4 7 pF
C2 2 2 -4 7 pF
3.0 TRANSMIT AND RECEIVE DATA There are two methods to load transmit data and unload receive data from each UART channel. First, there is a transmit data register and receive data register for each UART channel in the device configuration register set to ease programming. These registers support 8, 16, 24 and 32 bits wide format. In the 32-bit format, it increases the data transfer rate on the PCI bus. Additionally, a special register location provides receive data byte with its associated error tags. This is a 16-bit or 32-bit read operation where the Line Status Register (LSR) content in the UART channel register is paired along with the data byte. This operation further facilitates data unloading with the error tags without having to read the LSR register separately. Furthermore, the XR17L152 supports PCI burst mode for read/write operation of up to 64 bytes of data. The second method is through each UART channel's transmit holding register (THR) and receive holding register (RHR). The THR and RHR registers are 16550 compatible so their access is limited to 8-bit format. The software driver must separately read the LSR content for the associated error tags before reading the data byte.
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3.1
FIFO DATA LOADING AND UNLOADING THROUGH THE DEVICE CONFIGURATION REGISTERS IN 32-BIT FORMAT
The transmit and receive data registers are defined for channels 0 and 1 with each channel having its own address as shown in Table 2 for faster loading and unloading. The following paragraphs illustrate the receive and transmit data registers in more detail. Each Channel Normal Receive Data FIFO Address for channels 0 and 1 are at 0x0100 and 0x0300.
READ RX FIFO, WITH NO ERRORS Read n+0 to n+3 Read n+4 to n+7 Etc. BYTE 3 FIFO Data n+3 FIFO Data n+7 BYTE 2 FIFO Data n+2 FIFO Data n+6 BYTE 1 FIFO Data n+1 FIFO Data n+5 BYTE 0 FIFO Data n+0 FIFO Data n+4
Channel 0 to 1 ReceiveData in 32-bit alignment through the Configuration Register Address 0x0100 and 0x0300 Receive Data Byte n+3
B7 B6 B5 B4 B3 B2 B1 B0
Receive Data Byte n+2
B7 B6 B5 B4 B3 B2 B1 B0 B7
Receive Data Byte n+1
B6 B5 B4 B3 B2 B1 B0
Receive Data Byte n+0
B7 B6 B5 B4 B3 B2 B1 B0
PCI Bus Data Bit-31
PCI Bus Data Bit-0
Each Channel Normal Transmit Data FIFO Address for Channel 0 and 1 are at 0x0100 and 0x0300.
WRITE TX FIFO Write n+0 to n+3 Write n+4 to n+7 Etc. BYTE 3 FIFO Data n+3 FIFO Data n+7 BYTE 2 FIFO Data n+2 FIFO Data n+6 BYTE 1 FIFO Data n+1 FIFO Data n+5 BYTE 0 FIFO Data n+0 FIFO Data n+4
Channel 0 to 1 Transmit Data in 32-bit alignment through the Configuration Register Address 0x0100 and 0x0300 Transmit Data Byte n+3
B7 B6 B5 B4 B3 B2 B1 B0 B7
Transmit Data Byte n+2
B6 B5 B4 B3 B2 B1 B0
Transmit Data Byte n+1
B7 B6 B5 B4 B3 B2 B1 B0 B7
Transmit Data Byte n+0
B6 B5 B4 B3 B2 B1 B0
PCI Bus Data Bit-31
PCI Bus Data Bit-0
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Each Channel Special Receive FIFO Data Address for channel 0 and 1 are at 0x0180 and 0x380. The Status and Data bytes must be read in 16 or 32 bits format to maintain data integrity.
READ RX FIFO, ERRORS BYTE 3 FIFO Data n+1 FIFO Data n+3 BYTE 2 LSR n+1 LSR n+3 BYTE 1 FIFO Data n+0 FIFO Data n+2 BYTE 0 LSR n+0 LSR n+2
WITH LSR
Read n+0 to n+1 Read n+2 to n+3 Etc
Channel 0 to 1 Receive Data with Line Status Register in a 32-bit alignment through the Configuration Register Address 0x0180 and 0x0380 Receive Data Byte n+1
B7 B6 B5 B4 B3 B2 B1 B0 B7
Line Status Register n+1
B6 B5 B4 B3 B2 B1 B0
Receive Data Byte n+0
B7 B6 B5 B4 B3 B2 B1 B0 B7
Line Status Register n+0
B6 B5 B4 B3 B2 B1 B0
PCI Bus Data Bit-31
PCI Bus Data Bit-0
3.2
FIFO DATA LOADING AND UNLOADING THROUGH THE UART CHANNEL REGISTERS, THR AND RHR IN 8-BIT FORMAT
The THR and RHR register address for channel 0 to channel 1 is shown in Table 8 below. The THR and RHR for each channel 0 tand 1 are located sequentially at address 0x0000 and 0x0200. Transmit data byte is loaded to the THR when writing to that address and receive data is unloaded from the RHR register when reading that address. Both THR and RHR registers are 16C550 compatible in 8-bit format, so each bus operation can only write or read in bytes. TABLE 8: TRANSMIT AND RECEIVE DATA REGISTER IN BYTE FORMAT, 16C550 COMPATIBLE
THR and RHR Address Locations For CH0 to CH1 (16C550 Compatible) CH0 0x000 Write THR CH0 0x000 Read RHR CH1 0x200 Write THR CH1 0x200 Read RHR Bit-7 Bit-7 Bit-7 Bit-7 Bit-6 Bit-6 Bit-6 Bit-6 Bit-5 Bit-5 Bit-5 Bit-5 Bit-4 Bit-4 Bit-4 Bit-4 Bit-3 Bit-3 Bit-3 Bit-3 Bit-2 Bit-2 Bit-2 Bit-2 Bit-1 Bit-1 Bit-1 Bit-1 Bit-0 Bit-0 Bit-0 Bit-0
4.0 UART There are 2 UARTs [channels 1:0] in the L152. Each has its own 64-byte of transmit and receive FIFO, a set of 16550 compatible control and status registers, and a baud rate generator for individual channel data rate setting. Eight additional registers per UART were added for the EXAR enhanced features.
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4.1
Programmable Baud Rate Generator
Each UART has its own Baud Rate Generator (BRG) with a prescaler for the transmitter and receiver. The prescaler is controlled by a software bit in the MCR register. The MCR register bit-7 sets the prescaler to divide the input crystal or external clock by 1 or 4. The output of the prescaler clocks to the BRG. The BRG further divides this clock by a programmable divisor between 1 and (216 -1) to obtain a 16X or 8X sampling clock of the serial data rate. The sampling clock is used by the transmitter for data bit shifting and receiver for data sampling. The BRG divisor (DLL and DLM registers) defaults to a random value upon power up. Therefore, the BRG must be programmed during initialization to the operating data rate. FIGURE 8. BAUD RATE GENERATOR
To Channel 1
DLL and DLM Registers Prescaler Divide by 1 XTAL1 XTAL2 Crystal Osc/ Buffer Prescaler Divide by 4 MCR Bit-7=0 (default) Baud Rate Generator Logic MCR Bit-7=1
16X or 8X Sampling Rate Clock to Transmitter and Receiver
Programming the Baud Rate Generator Registers DLM and DLL provides the capability for selecting the operating data rate. Table 9 shows the standard data rates available with a 14.7456 MHz crystal or external clock at 16X clock rate. At 8X sampling rate, these data rates would double. When using a non-standard data rate crystal or external clock, the divisor value can be calculated with the following equation(s).
divisor (decimal) = (XTAL1 clock frequency / prescaler) / (serial data rate x 16), WITH 8XMODE [1:0] IS 0 divisor (decimal) = (XTAL1 clock frequency / prescaler) / (serial data rate x 8), WITH 8XMODE [1:0] IS 1
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TABLE 9: TYPICAL DATA RATES WITH A 14.7456 MHZ CRYSTAL OR EXTERNAL CLOCK AT 16X SAMPLING
OUTPUT Data Rate OUTPUT Data Rate DIVISOR FOR 16x DIVISOR FOR 16x DLM PROGRAM DLL PROGRAM DATA RATE MCR Bit-7=1 MCR Bit-7=0 Clock (Decimal) Clock (HEX) VALUE (HEX) VALUE (HEX) ERROR (%) 100 600 1200 2400 4800 9600 19.2k 38.4k 57.6k 115.2k 230.4k 400 2400 4800 9600 19.2k 38.4k 76.8k 153.6k 230.4k 460.8k 921.6k 2304 384 192 96 48 24 12 6 4 2 1 900 180 C0 60 30 18 0C 06 04 02 01 09 01 00 00 00 00 00 00 00 00 00 00 80 C0 60 30 18 0C 06 04 02 01 0 0 0 0 0 0 0 0 0 0 0
4.2
Automatic Hardware (RTS/CTS or DTR/DSR) Flow Control Operation
Automatic RTS/DTR and CTS/DSR flow control, also known as hardware flow control, is used to prevent data overrun to the local receiver FIFO and remote receiver FIFO. The RTS#/DTR# output pin is used to request remote unit to suspend/restart data transmission while the CTS#/DSR# input pin is monitored to suspend/ restart local transmitter. The auto RTS/DTR and auto CTS/DSR flow control features are individually selected to fit specific application requirement and enabled through EFR bit-6 and 7 and MCR bit-2 for either RTS/CTS or DTR/DSR control signals. The auto RTS/DTR function must be started by asserting RTS/DTR# output pin (MCR bit-0 or 1 to logic 1) after it is enabled. Figure 9 below explains how it works. Two interrupts associated with RTS/DTR and CTS/DSR flow control have been added to give indication when RTS/DTR# pin or CTS/DSR# pin is de-asserted during operation. The RTS/DTR and CTS/DSR interrupts must be first enabled by EFR bit-4, and then enabled individually by IER bit-6 and 7, and chosen with MCR bit-2. Automatic hardware flow control is selected by setting bits 6 (RTS) and 7 (CTS) of the EFR register to logic 1. If CTS# pin transitions from logic 0 to logic 1 indicting a flow control request, ISR bit-5 will be set to logic 1, (if enabled via IER bit 6-7), and the UART will suspend TX transmissions as soon as the stop bit of the character in process is shifted out. Transmission is resumed after the CTS# input returns to logic 0, indicating more data may be sent.
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FIGURE 9. AUTO RTS/DTR AND CTS/DSR FLOW CONTROL OPERATION
Local UART UARTA Receiver FIFO Trigger Reached Auto RTS Trigger Level Transmitter Auto CTS Monitor RXA TXB Remote UART UARTB Transmitter Auto CTS Monitor Receiver FIFO Trigger Reached Auto RTS Trigger Level
RTSA# TXA
CTSB# RXB
CTSA# Assert RTS# to Begin Transmission 1 ON 2 7 ON 3 8 OFF
RTSB#
RTSA# CTSB# TXB
OFF
10 11
ON ON
Data Starts 4 RXA FIFO INTA (RXA FIFO Interrupt) Receive Data RX FIFO Trigger Level 5
6
Suspend
Restart 9
RTS High Threshold
RTS Low Threshold
12
RX FIFO Trigger Level
RTSCTS1
The local UART (UARTA) starts data transfer by asserting -RTSA# (1). RTSA# is normally connected to CTSB# (2) of remote UART (UARTB). CTSB# allows its transmitter to send data (3). TXB data arrives and fills UARTA receive FIFO (4). When RXA data fills up to its receive FIFO trigger level, UARTA activates its RXA data ready interrupt (5) and continues to receive and put data into its FIFO. If interrupt service latency is long and data is not being unloaded, UARTA monitors its receive data fill level to match the upper threshold of RTS delay and de-assert RTSA# (6). CTSB# follows (7) and request UARTB transmitter to suspend data transfer. UARTB stops or finishes sending the data bits in its transmit shift register (8). When receive FIFO data in UARTA is unloaded to match the lower threshold of RTS delay (9), UARTA re-asserts RTSA# (10), CTSB# recognizes the change (11) and restarts its transmitter and data flow again until next receive FIFO trigger (12). This same event applies to the reverse direction when UARTA sends data to UARTB with RTSB# and CTSA# controlling the data flow.
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4.3 Infrared Mode
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
Each UART in the L152 includes the infrared encoder and decoder compatible to the IrDA (Infrared Data Association) version 1.0. The input pin ENIR conveniently activates both UART channels to start up in the infrared mode. This global control pin enables the MCR bit-6 function in every UART channel register. After power up or a reset, the software can overwrite MCR bit-6 if so desired. ENIR and MCR bit-6 also disable its receiver while the transmitter is sending data. This prevents the echoed data from going to the receiver. The global activation ENIR pin prevents the infrared emitter from turning on and drawing large amount of current while the system is starting up. When the infrared feature is enabled, the transmit data outputs, TX[1:0], would idle at logic zero level. Likewise, the RX[1:0] inputs assume an idle level of logic zero. The infrared encoder sends out a 3/16 of a bit wide pulse for each "0" bit in the transmit data stream. This signal encoding reduces the on-time of the infrared LED, hence reduces the power consumption. See Figure 10 below. The infrared decoder receives the input pulse from the infrared sensing diode on RX pin. Each time it senses a light pulse, it returns a logic zero to the data bit stream. The RX input signal may be inverted prior delivered to the input of the decoder. This option supports active low instead of normal active high pulse from some infrared modules on the market. FIGURE 10. INFRARED TRANSMIT DATA ENCODING AND RECEIVE DATA DECODING
C haracter Start D ata Bits 1 0 1 0 0 1 1 0 Stop 1 1/2 Bit Tim e 3/16 Bit Tim e
IrEncoder-1
TX D ata
0
Transm it IR Pulse (TX Pin) Bit Tim e
Receive IR Pulse (RX pin)
Bit Tim e 1/16 Clock Delay
RX Data
0 Start
1
0
1
0
0
1
1
0
1 Stop
IRdecoder-1
Data Bits Character
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4.4
Internal Loopback
Each UART channel provides an internal loopback capability for system diagnostic. The internal loopback mode is enabled by setting MCR register bit-4 to logic 1. All regular UART functions operate normally. Figure 11 shows how the modem port signals are re-configured. Transmit data from the transmit shift register output is internally routed to the receive shift register input allowing the system to receive the same data that it was sending. The TX pin is held at logic 1 or mark condition while RTS# and DTR# are de-asserted, and CTS#, DSR# CD# and RI# inputs are ignored. FIGURE 11. INTERNAL LOOP BACK FUNCTION IN EACH UART CHANNEL
VCC
Transmit Shift Register
MCR bit-4=1
TX [1:0]
Internal Bus Lines and Control Signals
Receive Shift Register
VCC
RX [1:0]
RTS# [1:0]
RTS#
Modem / General Purpose Control Logic
CTS#
CTS# [1:0]
VCC
DTR#
DTR# [1:0]
DSR# OP1# RI# OP2# CD#
DSR# [1:0]
RI# [1:0] CD# [1:0]
4.5
UART CHANNEL CONFIGURATION REGISTERS AND ADDRESS DECODING.
The 2 sets of UART configuration registers are decoded using address lines A9 to A11 as shown below.
A11 0 0 A10 0 0 A9 0 1 UART CHANNEL SELECTION 0 1
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XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
Address lines A0 to A3 select the 16 registers in each channel. The first 8 registers are 16550 compatible with the EXAR enhanced feature registers located on next 8 addresses locations. Addresses 0x080 to 0x093 comprise the Device Configuration Registers and they reside in Channel 0's space. . TABLE 10: UART CHANNEL CONFIGURATION REGISTERS.
ADDRESS A3 A2 A1 A0 16550 COMPATIBLE 0 0 00 RHR - Receive Holding Register THR - Transmit Holding Register DLL - Div Latch Low DLM - Div Latch High IER - Interrupt Enable Register ISR - Interrupt Status Register FCR - FIFO Control Register LCR - Line Control Register MCR - Modem Control Register LSR - Line Status Register reserved MSR - Modem Status Register - Auto RS485 Delay SPR - Scratch Pad Reg ENHANCED REGISTER 1 1 1 0 0 0 00 01 10 FCTR EFR - Enhanced Function Register TXCNT - Transmit FIFO Level Counter TXTRG - Transmit FIFO Trigger Level RXCNT - Receive FIFO Level Counter RXTRG - Receive FIFO Trigger Level Xoff-1 - Xoff Character 1 Xchar Xoff-2 - Xoff Character 2 reserved Xon-1 - Xon Character 1 reserved Xon-2 - Xon Character 2 reserved Read/Write Read/Write Read-only Write-only Read-only Write-only Write-only Read-only Write-only Read-only Write-only Read-only Write-only Read-only Read-only Write-only Read/Write Read/Write Read/Write Read-only Write-only Read/Write Read/Write Read-only Write-only Read-only Write-only Read/Write LCR[7] = 0 REGISTER READ/WRITE COMMENTS
0 0 0 0
0 0 0 0
00 01 01 10
LCR[7] = 1 LCR[7] = 1 LCR[7] = 0
0 0 0
0 1 1
11 00 01
0
1
10
0
1
11
1
0
11
1
1
00
Xon,Xoff Rcvd. Flags
1
1
01
1
1
10
1
1
11
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TABLE 11: UART CHANNEL CONFIGURATION REGISTERS DESCRIPTION. SHADED BITS ARE ENABLED BY EFR BIT-4.
ADDRESS A3-A0 0000 0000 0000 0001 0001 REG NAME RHR THR DLL DLM IER READ/ WRITE R W R/W R/W R/W BIT-7 Bit-7 Bit-7 Bit-7 Bit-7 0/ BIT-6 Bit-6 Bit-6 Bit-6 Bit-6 0/ BIT-5 Bit-5 Bit-5 Bit-5 Bit-5 0/ BIT-4 Bit-4 Bit-4 Bit-4 Bit-4 0 BIT-3 Bit-3 Bit-3 Bit-3 Bit-3 BIT-2 Bit-2 Bit-2 Bit-2 Bit-2 BIT-1 Bit-1 Bit-1 Bit-1 Bit-1 BIT-0 Bit-0 Bit-0 Bit-0 Bit-0 RX Data Int. Enable COMMENT LCR[7]=0 LCR[7]=0 LCR[7]=1 LCR[7]=1
CTS/ RTS/ Xon/Xoff/ DSR# Int. DTR# Int. Sp. Char. Enable Enable Int. Enable 0010 ISR R FIFOs Enable FIFOs Enable 0/ DeltaFlow Cntl 0010 FCR W RX FIFO Trigger RX FIFO Trigger 0/ TX FIFO Trigger 0011 LCR R/W Divisor Enable Set TX Break 0/ Xoff/special char 0/ TX FIFO Trigger
Modem RX Line TX Empty Status Int. Status Int. Int. Enable Enable Enable
INT Source Bit-3 DMA Mode
INT Source Bit-2 TX FIFO Reset
INT Source Bit-1 RX FIFO Reset
INT Source Bit-0 FIFOs Enable
Set Parity Even Parity
Parity Enable
Stop Bits
Word Length Bit-1
Word Length Bit-0
0100
MCR
R/W
0/ BRG Prescaler
0/ IR Enable TSR Empty RI
0/ XonAny
Internal Lopback Enable
(OP2)1
(OP1)1 RTS/DTR Flow Sel
RTS# Pin DTR# Pin Control Control
0101
LSR
R/W
RX FIFO ERROR CD
THR Empty DSR
RX Break
RX Fram- RX Parity RX Overing Error Error run Delta CD# Delta RI# Delta DSR#
RX Data Ready Delta CTS#
0110
MSR
R
CTS
MSR
W
RS485 DLY-3 Bit-7 TRG Table Bit-1
RS485 DLY-2 Bit-6 TRG Table Bit-0
RS485 DLY-1 Bit-5 Auto RS485 Enable Special Char Select
RS485 DLY- Reserved Reserved Reserved Reserved 0 Bit-4 Invert IR RX Input Bit-3 Bit-2 Bit-1 Bit-0 User Data
0111 1000
SPR FCTR
R/W R/W
RTS/DTR RTS/DTR RTS/DTR RTS/DTR Hyst Bit-3 Hyst Bit-2 Hyst Bit-1 Hyst Bit-0
1001
EFR
R/W
Auto CTS/ Auto RTS/ DSR DTR Enable Enable
Enable IER [7:5], ISR [5:4], FCR[5:4], MCR[7:5,2] MSR[7:4]
Software Software Software Software Flow Cntl Flow Cntl Flow Cntl Flow Cntl Bit-3 Bit-2 Bit-1 Bit-0
1010 1010 1011 1011
TXCNT TXTRG RXCNT RXTRG
R W R W
Bit-7 Bit-7 Bit-7 Bit-7
Bit-6 Bit-6 Bit-6 Bit-6
Bit-5 Bit-5 Bit-5 Bit-5
Bit-4 Bit-4 Bit-4 Bit-4
Bit-3 Bit-3 Bit-3 Bit-3
Bit-2 Bit-2 Bit-2 Bit-2
Bit-1 Bit-1 Bit-1 Bit-1
Bit-0 Bit-0 Bit-0 Bit-0
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ADDRESS A3-A0 1100 REG NAME XCHAR READ/ WRITE R
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
TABLE 11: UART CHANNEL CONFIGURATION REGISTERS DESCRIPTION. SHADED BITS ARE ENABLED BY EFR BIT-4.
BIT-7 BIT-6 BIT-5 BIT-4 BIT-3 BIT-2 BIT-1 Xon Det. Indicator Bit-7 Bit-7 Bit-7 Bit-7 Bit-6 Bit-6 Bit-6 Bit-6 Bit-5 Bit-5 Bit-5 Bit-5 Bit-4 Bit-4 Bit-4 Bit-4 Bit-3 Bit-3 Bit-3 Bit-3 Bit-2 Bit-2 Bit-2 Bit-2 Bit-1 Bit-1 Bit-1 Bit-1 BIT-0 COMMENT
Xoff Det. Self-clear Indicator after read Bit-0 Bit-0 Bit-0 Bit-0
1100 1101 1110 1111
XOFF1 XOFF2 XON1 XON2
W W W W
NOTE: MCR bits 2 and 3 (OP1 and OP2 outputs) are not available in the XR17L154. They are present for 16C550 compatibility during Internal loopback, see Figure 11.
4.6
Transmitter
The transmitter section comprises of 64 bytes of FIFO, a byte-wide Transmit Holding Register (THR) and an 8bit Transmit Shift Register (TSR). THR receives a data byte from the host (non-FIFO mode) or a data byte from the FIFO when the FIFO is enabled by FCR bit-0. TSR shifts out every data bit with the 16X or 8X internal clock. A bit time is 16 or 8 clock periods. The transmitter sends the start bit followed by the number of data bits, inserts the proper parity bit if enable, and adds the stop bit(s). The status of the THR and TSR are reported in the Line Status Register (LSR bit-5 and bit-6). 4.6.1 Transmit Holding Register (THR) The Transmit Holding Register is an 8-bit register providing a data interface to the host processor. The host writes transmit data byte to the THR to be converted into a serial data stream including start-bit, data bits, parity-bit and stop-bit(s). The least-significant-bit (Bit-0) becomes first data bit to go out. The THR is also the input register to the transmit FIFO of 64 bytes when FIFO operation is enabled by FCR bit-0. A THR empty interrupt can be generated when it is enabled in IER bit-1. 4.6.2 Transmitter Operation in non-FIFO The host loads transmit data to THR one character at a time. The THR empty flag (LSR bit-5) is set when the data byte is transferred to TSR. THR flag can generate a transmit empty interrupt (ISR bit-1) when it is enabled by IER bit-1. The TSR flag (LSR bit-6) is set when TSR becomes completely empty. FIGURE 12. TRANSMITTER OPERATION IN NON-FIFO MODE
D a ta B y te
T ra n s m it H o ld in g R e g is te r (T H R )
T H R In te rru p t (IS R b it-1 ) E n a b le d b y IE R b it-1
16X or 8X C lo c k (8 X M O D E R e g is te r) T ra n s m it S h ift R e g is te r (T S R )
M S B
L S B
T X N O F IF O 1
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4.6.3
Transmitter Operation in FIFO
The host may fill the transmit FIFO with up to 64 bytes of transmit data. The THR empty flag (LSR bit-5) is set whenever the FIFO is empty. The THR empty flag can generate a transmit empty interrupt (ISR bit-1) when the amount of data in the FIFO falls below its programmed trigger level (see TXTRG register). The transmit empty interrupt is enabled by IER bit-1. The TSR flag (LSR bit-6) is set when TSR becomes completely empty. Furthermore, with the RS485 half-duplex direction control enabled (FCTR bit-5=1) the source of the transmit empty interrupt changes to TSR empty instead of THR empty. This is to ensure the RTS# output is not changed until the last stop bit of the last character is shifted out. 4.6.4 Auto RS485 Operation The auto RS485 half-duplex direction control changes the behavior of the transmitter when enabled during powerup or reset by the EN485# pin or in software by FCTR bit-5. It de-asserts RTS# or DTR# after a specified delay indicated in MSR[7:4] following the last stop bit of the last character that has been transmitted. This helps in turning around the transceiver to receive the remote station's response. The delay optimizes the time needed for the last transmission to reach the farthest station on a long cable network before switching off the line driver. This delay prevents undesirable line signal disturbance that causes signal degradation. It also changes the transmitter empty interrupt to TSR empty instead of THR empty. FIGURE 13. TRANSMIITTER OPERATION IN FIFO AND FLOW CONTROL MODE
T ra nsm it D a ta B y te
T ra nsm it F IF O (6 4 -B yte )
F low C o n tro l C h a ra cte rs (X o ff1 /2 a nd X o n1 /2 R e g . A u to S o ftw are F lo w C on tro l
T H R In terru p t (IS R b it-1 ) fa lls b elow P ro g ra m m e d T rig g e r L ev el (T X T R G ) a n d th e n w h e n be co m e s e m pty. F IF O is E n a bled b y F C R bit-0 = 1
1 6X o r 8 X C lo ck (8 X M O D E R e g iste r) A u to C T S F lo w C on tro l (C T S # p in )
T ra nsm it D a ta S hift R eg iste r (T S R )
T X F IF O 1
4.7
Receiver
The receiver section contains an 8-bit Receive Shift Register (RSR) and Receive Holding Register (RHR). The RSR uses the 16X or 8X clock for timing. It verifies and validates every bit on the incoming character in the middle of each data bit. On the falling edge of a start or false start bit, an internal receiver counter starts counting at the 16X or 8X clock rate. After 8 or 4 clocks the start bit period should be at the center of the start bit. At this time the start bit is sampled and if it is still a logic 0 it is validated. Evaluating the start bit in this manner prevents the receiver from assembling a false character. The rest of the data bits and stop bits are sampled and validated in this same manner to prevent false framing. If there were any error(s), they are reported in the LSR bits 1-4 and an LSR interrupt is generated immediately if IER bit-2 is enabled. Upon unloading the receive data byte from RHR, the receive FIFO pointer is bumped and the LSR bits are immediately updated to reflect the status of the data byte in the RHR. The RHR can generate a receive data ready interrupt upon receiving a character or delay until it reaches the FIFO trigger level. Furthermore, data delivery to the host is guaranteed by a receive data ready time-out function when receive data does not reach the receive FIFO trigger level. This time-out delay is 4 word lengths as defined by LCR[1:0] plus 12 bits time. The RHR interrupt is enabled by IER bit-0.
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4.7.1 Receiver Operation in non-FIFO Mode
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
FIGURE 14. RECEIVER OPERATION IN NON-FIFO MODE
1 6 X o r 8 X C lo c k (8 X M O D E R e g is t e r )
R e c e iv e D a ta S h ift R e g is te r (R S R )
D a ta B it V a lid a t io n
R e c e iv e D a t a C h a ra c te r s
R e c e iv e D a ta B y te a n d E rr o rs
E r ro r T a g s in L S R b its 3 :1
R e c e iv e D a ta H o ld in g R e g is t e r (R H R )
R H R I n te r ru p t (IS R b it -2 )
4.7.2
Receiver Operation with FIFO
FIGURE 15. RECEIVER OPERATION IN FIFO AND FLOW CONTROL MODE
16X or 8X Sampling Clock (8XMODE Reg.)
Receive Data Shift Register (RSR)
Data Bit Validation
Receive Data Characters
64 bytes by 11bit wide FIFO
Example: - FIFO trigger level set at 48 bytes - RTS/DTR hyasteresis set at +/-8 chars. Data falls to 40 Error Tags (64-sets)
RTS#/DTR# re-asserts when data falls below the trigger level to restart remote transmitter. Enable by EFR bit-6=1, MCR bit-2. RHR Interrupt (ISR bit-2) is programmed at FIFO trigger level (RXTRG). FIFO is Enable by FCR bit-0=1 RTS#/DTR# de-asserts when data fills above the trigger level to suspend remote transmitter. Enable by EFR bit-6=1, MCR bit-2.
Receive Data FIFO (64-byte)
FIFO Trigger=48
Data fills to 56 Error Tags in LSR bits 3:1
Receive Data Byte and Errors
Receive Data
RXFIFO1
4.8
Registers
Receive Holding Register (RHR) The receive holding register is an 8-bit register that holds a receive data byte from the receive shift register (RSR). It provides the receive data interface to the host processor. The host reads the receive data byte on this register whenever a data byte is transferred from the RSR. The RHR is also part of the receive FIFO of 64 bytes by 11-bit wide, 3 extra bits are for the error tags in LSR. When the FIFO is enabled by FCR bit-0, the RHR contains the first data character received by the FIFO. After the RHR is read, the next character byte is loaded into the RHR and the errors associated with the current data byte are immediately updated in the LSR bits 1-4.
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Baud Rate Generator Divisors (DLL and DLM) The Baud Rate Generator (BRG) is a 16-bit counter that generates the data rate for the transmitter and receiver. The rate is programmed through registers DLL and DLM which are only accessible when LCR bit-7 is set to logic 1. See Programmable Baud Rate Generator section for more detail. Interrupt Enable Register (IER) The Interrupt Enable Register (IER) masks the interrupts from receive data ready, transmit empty, line status and modem status registers. These interrupts are reported in the Interrupt Status Register (ISR) register and also encoded in INT (INT0-INT3) register in the Device Configuration Registers. IER versus Receive FIFO Interrupt Mode Operation When the receive FIFO (FCR BIT-0 = logic 1) and receive interrupts (IER BIT-0 = logic 1) are enabled, the RHR interrupts (see ISR bits 3 and 4) status will reflect the following: A. The receive data available interrupts are issued to the host when the FIFO has reached the programmed trigger level. It will be cleared when the FIFO drops below the programmed trigger level. B. FIFO level will be reflected in the ISR register when the FIFO trigger level is reached. Both the ISR register status bit and the interrupt will be cleared when the FIFO drops below the trigger level. C. The receive data ready bit (LSR BIT-0) is set as soon as a character is transferred from the shift register to the receive FIFO. It is reset when the FIFO is empty. IER versus Receive/Transmit FIFO Polled Mode Operation When FCR BIT-0 equals a logic 1 for FIFO enable; resetting IER bits 0-3 enables the L152 in the FIFO polled mode of operation. Since the receiver and transmitter have separate bits in the LSR either or both can be used in the polled mode by selecting respective transmit or receive control bit(s). A. LSR BIT-0 indicates there is data in RHR or RX FIFO. B. LSR BIT 1-4 provides the type of receive data errors encountered for the data byte in RHR, if any. C. LSR BIT-5 indicates THR is empty. D. LSR BIT-6 indicates when both the transmit FIFO and TSR are empty. E. LSR BIT-7 indicates a data error in at least one character in the RX FIFO. IER[0]: RHR Interrupt Enable The receive data ready interrupt will be issued when RHR has a data character in the non-FIFO mode or when the receive FIFO has reached the programmed trigger level in the FIFO mode.
* Logic 0 = Disable the receive data ready interrupt (default). * Logic 1 = Enable the receiver data ready interrupt.
IER[1]: THR Interrupt Enable This interrupt is associated with bit-5 in the LSR register. An interrupt is issued whenever the THR becomes empty (non-FIFO mode) or when data in the FIFO falls below the programmed trigger level in the 64-byte FIFO mode.
* Logic 0 = Disable Transmit Holding Register empty interrupt (default). * Logic 1 = Enable Transmit Holding Register empty interrupt.
IER[2]: Receive Line Status Interrupt Enable If any of the LSR register bits 1, 2, 3 or 4 is a logic 1, it will generate an interrupt to inform the host controller about the error status of the current data byte in FIFO. An interrupt is generated immediately when a character with an error has been received.
* Logic 0 = Disable the receiver line status interrupt (default). * Logic 1 = Enable the receiver line status interrupt.
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IER[3]: Modem Status Interrupt Enable
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
* Logic 0 = Disable the modem status register interrupt (default). * Logic 1 = Enable the modem status register interrupt.
IER[4]: Reserved IER[5]: Xoff Interrupt Enable (requires EFR bit-4=1)
* Logic 0 = Disable the software flow control, receive Xoff interrupt (default). * Logic 1 = Enable the software flow control, receive Xoff interrupt. See Software Flow Control section for
details. IER[6]: RTS# Output Interrupt Enable (requires EFR bit-4=1)
* Logic 0 = Disable the RTS# interrupt (default). * Logic 1 = Enable the RTS# interrupt. The UART issues an interrupt when the RTS# output pin makes a
transition from low to high. IER[7]: CTS# Input Interrupt Enable (requires EFR bit-4=1)
* Logic 0 = Disable the CTS# interrupt (default). * Logic 1 = Enable the CTS# interrupt. The UART issues an interrupt when CTS# input pin makes a transition
low to high.
Interrupt Status Register (ISR)
The UART provides multiple levels of prioritized interrupts to minimize external software interaction. The Interrupt Status Register (ISR) provides the user with six interrupt status bits. Performing a read cycle on the ISR will give the user the current highest pending interrupt level to be serviced, others queue up for next service. No other interrupts are acknowledged until the pending interrupt is serviced. The Interrupt Source Table, Table 12, shows the data values (bit 0-5) for the six prioritized interrupt levels and the interrupt sources associated with each of these interrupt levels. Interrupt Generation:
* LSR is by any of the LSR bits 1, 2, 3 and 4. * RXRDY is by RX trigger level. * RXRDY Time-out is by the a 4-char plus 12 bits delay timer. * TXRDY is by LSR bit-5 in the non-FIFO mode, TX trigger level setting in the FIFO mode (or bit-6 in auto
RS485 control).
* MSR is by any of the MSR bits 0, 1, 2 and 3. * Receive Xon/Xoff/Special character is by detection of a Xon, Xoff or Special character. * CTS#/DSR# is by a change of state on the input pin (from low to high) with auto flow control enabled, EFR
bit-7, and depending on selection on MCR bit-2.
* RTS#/DTR# is when its receiver changes the state of the output pin (from low to high) during auto RTS/DTR
flow control enabled by EFR bit-6 and selection of MCR bit-2.
Interrupt Clearing:
* LSR interrupt is cleared by a read to the LSR register (but LSR status bits are not cleared). * RXRDY interrupt is cleared by reading data until FIFO falls below the trigger level. * RXRDY Time-out interrupt is cleared by emptying the RX FIFO. * TXRDY interrupt is cleared by a read to the ISR register. * MSR interrupt is cleared by a read to the MSR register. * Xon, Xoff or Special character interrupt is cleared by a read to ISR register. * RTS#/DTR# and CTS#/DSR# input status change interrupt is cleared by a read to the MSR register.
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TABLE 12: INTERRUPT SOURCE AND PRIORITY LEVEL
PRIORITY LEVEL 1 2 3 4 5 6 7 X BIT-5 0 0 0 0 0 0 1 0
ISR REGISTER STATUS BITS BIT-4 0 0 0 0 0 1 0 0 BIT-3 0 0 1 0 0 0 0 0 BIT-2 1 1 1 0 0 0 0 0 BIT-1 1 0 0 1 0 0 0 0 BIT-0 0 0 0 0 0 0 0 1
SOURCE OF THE INTERRUPT+
LSR (Receiver Line Status Register) RXRDY (Received Data Ready) RXRDY (Receive Data Time-out) TXRDY (Transmitter Holding Register Empty) MSR (Modem Status Register) RXRDY (Received Xon/Xoff or Special character) CTS#/DSR#, RTS#/DTR# change of state None (default)
ISR[0]: Interrupt Status
* Logic 0 = An interrupt is pending and the ISR contents may be used as a pointer to the appropriate interrupt
service routine.
* Logic 1 = No interrupt pending (default condition).
ISR[3:1]: Interrupt Status These bits indicate the source for a pending interrupt at interrupt priority levels 1, 2, 3 and 4 (See Interrupt Source Table 12). ISR[5:4]: Interrupt Status These bits are enabled when EFR bit-4 is set to a logic 1. ISR bit-4 indicates that the receiver detected a data match of the Xon or Xoff character(s). Note that once set to a logic 1, the ISR bit-4 will stay a logic 1 until a Xon character is received. ISR bit-5 indicates that CTS#/DSR# or RTS#/DTR# has changed state. ISR[7:6]: FIFO Enable Status These bits are set to a logic 0 when the FIFOs are disabled. They are set to a logic 1 when the FIFOs are enabled. FIFO Control Register (FCR) This register is used to enable the FIFOs, clear the FIFOs, set the transmit/receive FIFO trigger levels, and select the DMA mode. The DMA, and FIFO modes are defined as follows: FCR[0]: TX and RX FIFO Enable
* Logic 0 = Disable the transmit and receive FIFO (default). * Logic 1 = Enable the transmit and receive FIFOs. This bit must be set to logic 1 when other FCR bits are
written or they will not be programmed. FCR[1]: RX FIFO Reset This bit is only active when FCR bit-0 is a logic 1.
* Logic 0 = No receive FIFO reset (default). * Logic 1 = Reset the receive FIFO pointers and FIFO level counter logic (the receive shift register is not
cleared or altered). This bit will return to a logic 0 after resetting the FIFO.
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FCR[2]: TX FIFO Reset This bit is only active when FCR bit-0 is a logic 1.
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
* Logic 0 = No transmit FIFO reset (default). * Logic 1 = Reset the transmit FIFO pointers and FIFO level counter logic (the transmit shift register is not
cleared or altered). This bit will return to a logic 0 after resetting the FIFO. FCR[3]: DMA Mode Select This bit is only active when FCR bit-0 is a logic 1. This bit has no effect since TXRDY and RXRDY pins are not available in this device. It is provided for legacy software.
* Logic 0 = Set DMA to mode 0 (default). * Logic 1 = Set DMA to mode 1.
FCR[5:4]: Transmit FIFO Trigger Select (logic 0 = default, TX trigger level = one) The FCTR Bits 6-7 are associated with these 2 bits by selecting one of the four tables. The 4 user selectable trigger levels in 4 tables are supported for compatibility reasons. These 2 bits set the trigger level for the transmit FIFO interrupt. The UART will issue a transmit interrupt when the number of characters in the FIFO falls below the selected trigger level, or when it gets empty in case that the FIFO did not get filled over the trigger level on last re-load. Table 13 below shows the selections. Note that the receiver and the transmitter cannot use different trigger tables. Whichever selection is made last applies to both the RX and TX side. FCR[7:6]: Receive FIFO Trigger Select (logic 0 = default, RX trigger level =1) The FCTR Bits 6-7 are associated with these 2 bits. These 2 bits are used to set the trigger level for the receiver FIFO interrupt. Table 13 shows the complete selections. Note that the receiver and the transmitter cannot use different trigger tables. Whichever selection is made last applies to both the RX and TX side.
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TABLE 13: TRANSMIT AND RECEIVE FIFO TRIGGER LEVEL SELECTION
FCTR BIT-7 0 FCTR BIT-6 0 0 0 1 1 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 0 1 0 1 0 0 1 1 0 0 1 1 1 1 X 0 1 0 1 X X X 0 1 0 1 8 16 56 60 Programmable Programmable Table-D. 16C850, 16C2850, via RXTRG reg- via TXTRG reg- 16C2852, 16C854, 16C864, ister ister 16C872 compatible. 0 1 0 1 8 16 24 28 8 16 32 56 Table-C. 16C654 compatible. FCR BIT-7 FCR BIT-6 FCR BIT-5 0 FCR
BIT-4
RECEIVE TRIGGER LEVEL
TRANSMIT TRIGGER LEVEL 1 (default)
COMPATIBILITY Table-A. 16C550, 16C2550, 16C2552, 16C554, 16C580 compatible.
0 1 (default) 4 8 14
16 8 24 30
Table-B. 16C650A compatible.
Line Control Register (LCR) The Line Control Register is used to specify the asynchronous data communication format. The word or character length, the number of stop bits, and the parity are selected by writing the appropriate bits in this register. LCR[1:0]: TX and RX Word Length Select These two bits specify the word length to be transmitted or received.
BIT-1 0 0 1 1 BIT-0 0 1 0 1 WORD LENGTH 5 (default) 6 7 8
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LCR[2]: TX and RX Stop-bit Length Select
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
The length of stop bit is specified by this bit in conjunction with the programmed word length.
BIT-2 0 1 1 WORD LENGTH 5,6,7,8 5 6,7,8 STOP BIT LENGTH (BIT TIME(S)) 1 (default) 1-1/2 2
LCR[3]: TX and RX Parity Select Parity or no parity can be selected via this bit. The parity bit is a simple way used in communications for data integrity check. See Table 14 for parity selection summary below.
* Logic 0 = No parity. * Logic 1 = A parity bit is generated during the transmission while the receiver checks for parity error of the
data character received. LCR[4]: TX and RX Parity Select If the parity bit is enabled with LCR bit-3 set to a logic 1, LCR BIT-4 selects the even or odd parity format.
* Logic 0 = ODD Parity is generated by forcing an odd number of logic 1's in the transmitted character. The
receiver must be programmed to check the same format (default).
* Logic 1 = EVEN Parity is generated by forcing an even the number of logic 1's in the transmitted character.
The receiver must be programmed to check the same format. LCR[5]: TX and RX Parity Select If the parity bit is enabled, LCR BIT-5 selects the forced parity format.
* LCR BIT-5 = logic 0, parity is not forced (default). * LCR BIT-5 = logic 1 and LCR BIT-4 = logic 0, parity bit is forced to a logical 1 for the transmit and receive
data.
* LCR BIT-5 = logic 1 and LCR BIT-4 = logic 1, parity bit is forced to a logical 0 for the transmit and receive
data. TABLE 14: PARITY SELECTION
LCR BIT-5 LCR BIT-4 LCR BIT-3 X 0 0 1 1 X 0 1 0 1 0 1 1 1 1 PARITY SELECTION No parity Odd parity Even parity Force parity to mark, "1" Force parity to space, "0"
LCR[6]: Transmit Break Enable When enabled the Break control bit causes a break condition to be transmitted (the TX output is forced to a "space", logic 0, state). This condition remains until disabled by setting LCR bit-6 to a logic 0.
* Logic 0 = No TX break condition (default). * Logic 1 = Forces the transmitter output (TX) to a "space", logic 0, for alerting the remote receiver of a line
break condition.
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LCR[7]: Baud Rate Divisors Enable Baud rate generator divisor (DLL/DLM) enable.
* Logic 0 = Data registers are selected (default). * Logic 1 = Divisor latch registers are selected.
Modem Control Register (MCR) or General Purpose Outputs Control The MCR register is used for controlling the serial/modem interface signals or general purpose inputs/outputs. MCR[0]: DTR# Pins The DTR# pin may be used for automatic hardware flow control enabled by EFR bit-6 and MCR bit-2=1. If the modem interface is not used, this output may be used for general purpose.
* Logic 0 = Force DTR# output to a logic 1 (default). * Logic 1 = Force DTR# output to a logic 0.
MCR[1]: RTS# Pins The RTS# pin may be used for automatic hardware flow control by enabled by EFR bit-6 and MCR bit-2=0. If the modem interface is not used, this output may be used for general purpose.
* Logic 0 = Force RTS# output to a logic 1 (default). * Logic 1 = Force RTS# output to a logic 0.
MCR[2]: DTR# or RTS# for Auto Flow Control The OP1 output is not available in the XR17L152. It is present for 16C550 compatibility during internal loopback. See Figure 11. Logic zero is default. DTR# or RTS# auto hardware flow control select. This bit is in effect only when auto RTS/DTR is enabled by EFR bit-6.
* Logic 0 = Uses RTS#/CTS# pins for auto hardware flow control. * Logic 1 = Uses DTR#/DSR# pin is used for auto hardware flow control.
MCR[3]: (OP2) The OP2 output is not available in the XR17L152. It is present for 16C550 compatibility during internal loopback. See Figure 11. Logic zero is default. MCR[4]: Internal Loopback Enable
* Logic 0 = Disable loopback mode (default). * Logic 1 = Enable local loopback mode, see loopback section and Figure 11.
MCR[5]: Xon-Any Enable
* Logic 0 = Disable Xon-Any function (for 16C550 compatibility) (default). * Logic 1 = Enable Xon-Any function. In this mode any RX character received will enable Xon, resume data
transmission. MCR[6]: Infrared Encoder/Decoder Enable This bit overrides the ENIR pin selection.
* Logic 0 = Disable the infrared mode (default). * Logic 1 = Enable infrared IrDA receive and transmit inputs/outputs. While in this mode, the TX/RX output/
input are routed to the infrared encoder/decoder. The data input and output levels will conform to the IrDA infrared interface requirement. As such, while in this mode the infrared TX output will be a logic 0 during idle data conditions. FCTR bit-4 may be selected to invert the RX input signal level going to the decoder for infrared modules that provide rather an inverted output.
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MCR[7]: Clock Prescaler Select
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
* Logic 0 = Divide by one. The input clock from the crystal or external clock is fed directly to the Programmable
Baud Rate Generator without further modification, i.e., divide by one (default).
* Logic 1 = Divide by four. The prescaler divides the input clock from the crystal or external clock by four and
feeds it to the Programmable Baud Rate Generator, hence, data rates become one forth. Line Status Register (LSR) This register provides the status of data transfers between the UART and the host. If IER bit-2 is enabled, an LSR interrupt is generated when a received data error occurs due to Overrrun, Parity or Framing. If LSR[0] = logic 0, then LSR bits 1-4 are invalid. LSR[0]: Receive Data Ready Indicator
* Logic 0 = No data in receive holding register or FIFO (default). * Logic 1 = Data has been received and is saved in the receive holding register or FIFO.
LSR[1]: Receiver Overrun Tag
* Logic 0 = No overrun error (default). * Logic 1 = Overrun error. A data overrun error condition occurred in the receive shift register. This happens
when additional data arrives while the FIFO is full. In this case the previous data in the receive shift register is overwritten. Note that under this condition the data byte in the receive shift register is not transferred into the FIFO, therefore the data in the FIFO is not corrupted by the error. Automatic Hardware (RTS/CTS) or Software (Xon/Xoff) Flow Control should be considered if this condition persists. LSR[2]: Receive Data Parity Error Tag
* Logic 0 = No parity error (default). * Logic 1 = Parity error. The receive character in RHR does not have correct parity information and is suspect.
This error is associated with the character available for reading in RHR. LSR[3]: Receive Data Framing Error Tag
* Logic 0 = No framing error (default). * Logic 1 = Framing error. The receive character did not have a valid stop bit(s). This error is associated with
the character available for reading in RHR. LSR[4]: Receive Break Flag
* Logic 0 = No break condition (default). * Logic 1 = The receiver received a break signal (RX was a logic 0 for one character frame time). In the FIFO
mode, only one break character is loaded into the FIFO. The break indication remains until the RX input returns to the idle condition, "mark" or logic 1. LSR[5]: Transmit Holding Register Empty Flag This bit is the Transmit Holding Register Empty indicator. This bit indicates that the transmitter is ready to accept a new character for transmission. In addition, this bit causes the UART to issue an interrupt to the host when the THR interrupt enable is set. The THR bit is set to a logic 1 when the last data byte is transferred from the transmit holding register to the transmit shift register. The bit is reset to logic 0 concurrently with the data loading to the transmit holding register by the host. In the FIFO mode this bit is set when the transmit FIFO is empty; it is cleared when at least 1 byte is written to the transmit FIFO. LSR[6]: Transmit Shift Register Empty Flag This bit is the Transmit Shift Register Empty indicator. This bit is set to a logic 1 whenever the transmitter goes idle. It is set to logic 0 whenever either the THR or TSR contains a data character. In the FIFO mode this bit is set to one whenever the transmit FIFO and transmit shift register are both empty.
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LSR[7]: Receive FIFO Data Error Flag
* Logic 0 = No FIFO error (default). * Logic 1 = An indicator for the sum of all error bits in the RX FIFO. At least one parity error, framing error or
break indication is in the FIFO data. This bit clears when there is no more error(s) in the FIFO. Modem Status Register (MSR) - Read Only This register provides the current state of the modem interface signals, or other peripheral device that the UART is connected. Lower four bits of this register are used to indicate the changed information. These bits are set to a logic 1 whenever a signal from the modem changes state. These bits may be used as general purpose inputs/outputs when they are not used with modem signals. MSR[0]: Delta CTS# Input Flag
* Logic 0 = No change on CTS# input (default). * Logic 1 = The CTS# input has changed state since the last time it was monitored. A modem status interrupt
will be generated if MSR interrupt is enabled (IER bit-3). MSR[1]: Delta DSR# Input Flag
* Logic 0 = No change on DSR# input (default). * Logic 1 = The DSR# input has changed state since the last time it was monitored. A modem status interrupt
will be generated if MSR interrupt is enabled (IER bit-3). MSR[2]: Delta RI# Input Flag
* Logic 0 = No change on RI# input (default). * Logic 1 = The RI# input has changed from a logic 0 to a logic 1, ending of the ringing signal. A modem status
interrupt will be generated if MSR interrupt is enabled (IER bit-3). MSR[3]: Delta CD# Input Flag
* Logic 0 = No change on CD# input (default). * Logic 1 = Indicates that the CD# input has changed state since the last time it was monitored. A modem
status interrupt will be generated if MSR interrupt is enabled (IER bit-3). MSR[4]: CTS Input Status CTS# pin may function as automatic hardware flow control signal input if it is enabled and selected by Auto CTS (EFR bit-7) and RTS/CTS flow control select (MCR bit-2). Auto CTS flow control allows starting and stopping of local data transmissions based on the modem CTS# signal. A logic 1 on the CTS# pin will stop UART transmitter as soon as the current character has finished transmission, and a logic 0 will resume data transmission. Normally MSR bit-4 bit is the compliment of the CTS# input. However in the loopback mode, this bit is equivalent to the RTS# bit in the MCR register. The CTS# input may be used as a general purpose input when the modem interface is not used. MSR[5]: DSR Input Status DSR# (active high, logical 1). This input may be used for auto DTR/DSR flow control function, see auto \hardware flow control section. Normally this bit is the compliment of the DSR# input. In the loopback mode, this bit is equivalent to the DTR# bit in the MCR register. The DSR# input may be used as a general purpose input when the modem interface is not used. MSR[6]: RI Input Status RI# (active high, logical 1). Normally this bit is the compliment of the RI# input. In the loopback mode this bit is equivalent to bit-2 in the MCR register. The RI# input may be used as a general purpose input when the modem interface is not used.
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MSR[7]: CD Input Status
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
CD# (active high, logical 1). Normally this bit is the compliment of the CD# input. In the loopback mode this bit is equivalent to bit-3 in the MCR register. The CD# input may be used as a general purpose input when the modem interface is not used. Modem Status Register (MSR) - Write Only The upper four bits 4-7 of this register sets the delay in number of bits time for the auto RS485 turn around from transmit to receive. MSR [7:4] When Auto RS485 feature is enabled (FCTR bit-5=1) and RTS# output is connected to the enable input of a RS-485 transceiver. These 4 bits select from 0 to 15 bit-time delay after the end of the last stop-bit of the last transmitted character. This delay controls when to change the state of RTS# output. This delay is very useful in long-cable networks. Table 15 shows the selection. The bits are enabled by EFR bit-4. TABLE 15: AUTO RS485 HALF-DUPLEX DIRECTION CONTROL DELAY FROM TRANSMIT-TO-RECEIVE
MSR[7] 0 0 0 0 0 9 0 0 1 1 1 1 1 1 1 1 Scratch Pad Register (SPR) MSR[6] 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 MSR[5] 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 MSR[4] 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 DELAY IN DATA BIT(S) TIME 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
This is an 8-bit general purpose register for the user to store temporary data. The content of this register is preserved during sleep mode but becomes 0xFF (default) after a reset or a power off-on cycle.
Feature Control Register (FCTR)
This register controls the UART enhanced functions that are not available on ST16C554 or ST16C654.
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FCTR [3:0] - Auto RTS/DTR Flow Control Hysteresis Select These bits select the auto RTS/DTR flow control hysteresis and only valid when TX and RX Trigger Table-D is selected (FCTR bit-6 and 7 are set to logic 1). The RTS/DTR hysteresis is referenced to the RX FIFO trigger level. After reset, these bits are set to logic 0 selecting the next FIFO trigger level for hardware flow control. Table 16 below shows the 16 selectable hysteresis levels. TABLE 16: 16 SELECTABLE HYSTERESIS LEVELS WHEN TRIGGER TABLE-D IS SELECTED
FCTR BIT-3 FCTR BIT-2 FCTR BIT-1 FCTR BIT-0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 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 RTS/DTR HYSTERESIS (CHARACTERS) 0 +/- 4 +/- 6 +/- 8 +/- 8 +/- 16 +/- 24 +/- 32 +/- 12 +/- 20 +/- 28 +/- 36 +/- 40 +/- 44 +/- 48 +/- 52
FCTR[4]: Infrared RX Input Logic Select
* Logic 0 = Select RX input as active high encoded IrDA data, normal, (default). * Logic 1 = Select RX input as active low encoded IrDA data, inverted.
FCTR[5]: Auto RS485 Enable This bit overrides the EN485# pin selection. Auto RS485 half duplex control enable/disable.
* Logic 0 = Standard ST16C550 mode. Transmitter generates an interrupt when transmit holding register
(THR) becomes empty. Transmit Shift Register (TSR) may still be shifting data bit out.
* Logic 1 = Enable Auto RS485 half duplex direction control. RTS# output changes its logic level from 1 to 0
when finished sending the last stop bit of the last character out of the TSR register. It changes back to logic level 1 from 0 when a data byte is loaded into the THR or transmit FIFO. The change to logic 1 occurs prior sending the start-bit. It also changes the transmitter interrupt from transmit holding to transmit shift register (TSR) empty.
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FCTR[7:6]: TX and RX FIFO Trigger Table Select
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
These 2 bits select the transmit and receive FIFO trigger level table A, B, C or D. When table A, B, or C is selected the auto RTS flow control trigger level is set to "next FIFO trigger level" for compatibility to ST16C550 and ST16C650 series. RTS/DTR# triggers on the next level of the RX FIFO trigger level, in another word, one FIFO level above and one FIFO level below. See Table 13 for complete selection with FCR bit 4-5 and FCTR bit 6-7, i.e. if Table C is used on the receiver with RX FIFO trigger level set to 56 bytes, RTS/DTR# output will deasserts at 60 and re-asserts at 16. Enhanced Feature Register (EFR) Enhanced features are enabled or disabled using this register. Bit 0-3 provide single or dual consecutive character software flow control selection (see Table 17). When the Xon1 and Xon2 and Xoff1 and Xoff2 modes are selected, the double 8-bit words are concatenated into two sequential characters. Caution: note that whenever changing the TX or RX flow control bits, always reset all bits back to logic 0 (disable) before programming a new setting. EFR[3:0]: Software Flow Control Select Combinations of software flow control can be selected by programming these bits (see Table 17). TABLE 17: SOFTWARE FLOW CONTROL FUNCTIONS
EFR BIT-3 CONT-3 0 0 1 0 1 X X X 1 EFR BIT-2 CONT-2 0 0 0 1 1 X X X 0 EFR BIT-1 CONT-1 0 X X X X 0 1 0 1 EFR BIT-0 CONT-0 0 X X X X 0 0 1 1 TRANSMIT AND RECEIVE SOFTWARE FLOW CONTROL No TX and RX flow control (default and reset) No transmit flow control Transmit Xon1/Xoff1 Transmit Xon2/Xoff2 Transmit Xon1 and Xon2/Xoff1 and Xoff2 No receive flow control Receiver compares Xon1/Xoff1 Receiver compares Xon2/Xoff2 Transmit Xon1/ Xoff1, Receiver compares Xon1 or Xon2, Xoff1 or Xoff2 Transmit Xon2/Xoff2, Receiver compares Xon1 or Xon2, Xoff1 or Xoff2 Transmit Xon1 and Xon2/Xoff1 and Xoff2, Receiver compares Xon1 and Xon2/Xoff1 and Xoff2 No transmit flow control, Receiver compares Xon1 and Xon2/Xoff1 and Xoff2
0
1
1
1
1
1
1
1
0
0
1
1
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EFR[4]: Enhanced Function Bits Enable Enhanced function control bit. This bit enables the functions in IER bits 4-7, ISR bits 4-5, FCR bits 4-5, and MCR bits 5-7 to be modified. After modifying any enhanced bits, EFR bit-4 can be set to a logic 0 to latch the new values. This feature prevents legacy software from altering or overwriting the enhanced functions once set. Normally, it is recommended to leave it enabled, logic 1.
* Logic 0 = modification disable/latch enhanced features. IER bits 4-7, ISR bits 4-5, FCR bits 4-5, and MCR
bits 5-7 are saved to retain the user settings. After a reset, the IER bits 4-7, ISR bits 4-5, FCR bits 4-5, and MCR bits 5-7 are set to a logic 0 to be compatible with ST16C554 mode (default).
* Logic 1 = Enables the enhanced functions. When this bit is set to a logic 1 all enhanced features are enabled.
EFR[5]: Special Character Detect Enable
* Logic 0 = Special Character Detect Disabled (default). * Logic 1 = Special Character Detect Enabled. The UART compares each incoming receive character with
data in Xoff-2 register. If a match exists, the received data will be transferred to FIFO and ISR bit-4 will be set to indicate detection of the special character. Bit-0 corresponds with the LSB bit for the receive character. If flow control is set for comparing Xon1, Xoff1 (EFR [1:0]='10') then flow control and special character work normally. However, if flow control is set for comparing Xon2, Xoff2 (EFR[1:0]='01') then flow control works normally, but Xoff2 will not go to the FIFO, and will generate an Xoff interrupt and a special character interrupt. EFR[6]: Auto RTS or DTR Flow Control Enable RTS#/DTR# output may be used for hardware flow control by setting EFR bit-6 to logic 1. When Auto RTS/DTR is selected, an interrupt will be generated when the receive FIFO is filled to the programmed trigger level and RTS/DTR# will de-assert to a logic 1 at the next upper trigger or selected hysteresis level. RTS/DTR# will return to a logic 0 when FIFO data falls below the next lower trigger or selected hysteresis level (see FCTR bits 4-7). The RTS# or DTR# output must be asserted (logic 0) before the auto RTS/DTR can take effect. The selection for RTS# or DTR# is through MCR bit-2. RTS/DTR# pin will function as a general purpose output when hardware flow control is disabled.
* Logic 0 = Automatic RTS/DTR flow control is disabled (default). * Logic 1 = Enable Automatic RTS/DTR flow control.
EFR[7]: Auto CTS Flow Control Enable Automatic CTS or DSR Flow Control.
* Logic 0 = Automatic CTS/DSR flow control is disabled (default). * Logic 1 = Enable Automatic CTS/DSR flow control. Transmission stops when CTS/DSR# pin de-asserts to
logic 1. Transmission resumes when CTS/DSR# pin returns to a logic 0. The selection for CTS# or DSR# is through MCR bit-2.
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TXCNT[7:0]: Transmit FIFO Level Counter, read-only
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
Transmit FIFO level byte count from 0x00 (zero) to 0x40 (64). This 8-bit register gives an indication of the number of characters in the transmit FIFO. The FIFO level Byte count register is read only. The user can take advantage of the FIFO level byte counter for faster data loading to the transmit FIFO, which reduces CPU bandwidth requirements. TXTRG [7:0]: Transmit FIFO Trigger Level, write-only An 8-bit value written to this register sets the TX FIFO trigger level from 0x00 (zero) to 0x40 (64). The TX FIFO trigger level generates an interrupt whenever the data level in the transmit FIFO falls below this preset trigger level. RXCNT[7:0]: Receive FIFO Level Counter, read-only Receive FIFO level byte count from 0x00 (zero) to 0x40 (64). It gives an indication of the number of characters in the receive FIFO. The FIFO level byte count register is read only. The user can take advantage of the FIFO level byte counter for faster data unloading from the receiver FIFO, which reduces CPU bandwidth requirements. RXTRG[7:0]: Receive FIFO Trigger Level, write only An 8-bit value written to this register, sets the RX FIFO trigger level from 0x00 (zero) to 0x40 (64). The RX FIFO trigger level generates an interrupt whenever the receive FIFO level rises to this preset trigger level.
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TABLE 18: UART[1:0] RESET CONDITIONS
REGISTERS DLL DLM RHR THR IER FCR ISR LCR MCR LSR MSR RESET STATE Bits 7-0 = 0xXX Bits 7-0 = 0xXX Bits 7-0 = 0xXX Bits 7-0 = 0xXX Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x01 Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x60 Bits 3-0 = logic 0 Bits 7-4 = logic levels of the inputs Bits 7-0 = 0xFF Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00 Bits 7-0 = 0x00 RESET STATE Logic 1 Logic 0 Logic 1 Logic 1 Logic 0 Logic 0 Logic 0
SPR FCTR EFR TXCNT TXTRG RXCNT RXTRG XCHAR XON1 XON2 XOFF1 XOFF2 I/O SIGNALS TX[ch-1:0] IRTX[ch-1:0] RTS#[ch-1:0] DTR#[ch-1:0] EECK EECS EEDI
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ABSOLUTE MAXIMUM RATINGS
Power Supply Range Voltage at Any Pin Operating Temperature Storage Temperature Package Dissipation Thermal Resistance (20x20x1.0mm 144-TQFP)
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
4 Volts -0.5 to 4V -40o to +85o C -65o to +150o C 500 mW theta-ja = 45, theta-jc = 7 oC/W
ELECTRICAL CHARACTERISTICS
DC ELECTRICAL CHARACTERISTICS FOR 3.3V SIGNALLING
TA=0o to 70oC (-40o to +85oC for industrial grade package), Vcc = 3.3V +/-10% unless otherwise specified.
SYMBOL VIL VIH VOL VOH IIL IIH PARAMETER Input Low Voltage Input High Voltage MIN -0.5 0.5Vcc MAX 0.3Vcc Vcc + 0.5 UNITS V V For PCI bus and exter- For non-PCI inputs, VIH nal clock inputs max = 6.0 V IOL = 4mA IOH = -0.5mA CONDITION NOTES
Output Low Voltage Output High Voltage Input Low Leakage Current Input High Leakage Current 0.9Vcc
0.4
V V
-10 10
A A
ICL CIN CCLK CIDSEL ICC
Input Clock Leakage Input Pin Capacitance CLK Pin Capacitance IDSEL Pin Capacitance Power Supply Current
+/-10 10 12 8 2
A pF pF pF mA PCI CLK and Ext. Clock=2MHz, all inputs are at VCC or GND and all outputs are unloaded All four UARTs asleep. AD[31:0] at GND, all inputs at VCC or GND
ISLEEP
Sleep Current
20
A
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AC ELECTRICAL CHARACTERISTICS FOR 3.3V SIGNALING
TA=0o to 70oC (-40o to +85oC for industrial grade package), Vcc = 3.3V +/-10% unless otherwise specified.
SYMBOL CLK XTAL1 XTAL2 ECLK PARAMETER PCI Bus Clock Crystal Oscillator MIN MAX 33 24 UNITS MHz MHz On-chip osc. NOTES
External Clock
33
MHz
Ext. clock on XTAL1
IOH(AC) IOL(AC) ICH ICL SlewR SlewF
Switching Current High Switching Current Low Clamping Current High Clamping Current Low Output Rise Slew Rate Output Fall Slew Rate
-12Vcc 16Vcc 25+(Vin-Vcc-1)/0.015 -25+(Vin+1)/0.015 1 1 4 4
mA mA mA mA V/ns V/ns
0 < Vout 0.3Vcc Vcc > Vout 0.6Vcc Vcc+4 > Vin Vcc+1 -3 < Vin -1 0.2Vcc - 0.6Vcc load 0.6Vcc - 0.2Vcc load
TCYC THI TLO
CLK Cycle Time CLK High Time CLK Low Time CLK Slew Rate
30 11 11 1 2 2
ns ns ns
4 11
V/ns ns ns
TVAL TON TOFF TSETUP THOLD
CLK to Signal Valid Delay Float to Active Delay Active to Float Delay Input Setup Time to CLK bused signals Input Hold Time from CLK
28 7 0
ns ns ns
TPRST TCRST#
RST# Active Time After Power Stable RST# Active Time After CLK Stable RST# Slew Rate
1 100 50
ms us mV/ns
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XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
FIGURE 16. PCI BUS CONFIGURATION SPACE REGISTERS READ AND WRITE OPERATION
C LK
H ost 1 2 3 4
FR A M E#
H ost
A D[31:0]
H ost Ta rg e t
ADDRESS
D A TA
C /BE [3:0]#
H ost
C FG -R D
B Y TE E N A B L E #
IR DY #
H ost
TR D Y#
Ta rg e t
D EV SEL #
Ta rg e t P C IC FG _R D
C LK
H os t 1 2 3 4
FR A M E#
H os t
A D[31:0]
H os t T a rg e t
ADDRESS
W R IT E D A T A
C /BE [3:0]#
H os t
C F G -W R
B Y TE E N A B L E #
IR DY #
H os t
TR D Y#
T a rg e t
D EV SEL #
T a rg e t P C IC F G _W R
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DATA TRANSFER
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FIGURE 17. DEVICE CONFIGURATION AND UART REGISTERS READ OPERATION FOR A BYTE OR DWORD
CLK
Host
1
2
3
4
5
6
7
8
9
10
11
FRAME#
Host
AD[31:0]
Host Target
Address
Data BYTE
Data WORD
C/BE[3:0]#
Host
Bus CMD
Byte Enable# = BYTE BYTE TRANSFER
Byte Enable# = DWORD DWORD TRANSFER Data Parity
IRDY#
Host
WAIT
WAIT
WAIT
TRDY#
Target
DEVSEL#
Target
WAIT
PAR
Host Target
Address Parity
Data Parity
PERR#
Target
Active
WAIT
Active
SERR# Targe
t
Active
Note: PERR# and SERR are optional in a bus target application. Even Parity is on AD[31:0], C/BE[3:0]#, and PAR
PCI_RD1
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TION
XR17L152 3.3V PCI BUS DUAL UART
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FIGURE 18. DEVICE CONFIGURATION REGISTERS, UART REGISTERS AND TRANSMIT DATA BURST WRITE OPERA-
CLK
H o st
1
2
3
4
5
6
7
8
9
10
11
FRAM E#
H o st
AD[31:0]
H o st T a rg e t
A dd ress
D ata DW ORD
D ata DW ORD
D ata DW ORD
D ata DW ORD
D a ta D W O R D
C/BE[3:0]#
H o st
B us CMD
B yte E n a b le # = D W O R D
DWORD TRANSFER
DWORD TRANSFER
DWORD TRANSFER
DWORD TRANSFER
IRDY#
H o st
TRDY#
T a rg e t
DEVSEL#
T a rg e t
PAR
H o st T a rg e t
A dd ress P arity
D ata P arity
D ata P arity
D ata P arity
D ata P arity
DWORD TRANSFER D ata P arity
PERR#
T a rg e t
A ctive
A ctive
A ctive
A ctive
A ctive
SERR#
T a rg e t
A ctive
N o te : P E R R # a nd S E R R a re o ptio n al in a bu s ta rg e t a p plica tion . E ve n P a rity is o n A D [31 :0 ], C /B E [3:0 ]# , a n d P A R
P C I_B W R
50
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
ac
DISCONTINUED
FIGURE 19. DEVICE CONFIGURATION REGISTERS, UART REGISTERS AND RECEIVE DATA BURST READ OPERATION
CLK
H ost
1
8
13
18
23
FRAM E#
H ost
AD[31:0]
H ost Target
AD
D ata
D ata
D ata
D ata
C/BE[3:0]#
H ost
Bus CMD
Byte Ena ble# = D W O R D
DWORD TRANSFER
DWORD TRANSFER
DWORD TRANSFER
H ost
TRDY#
Target
DEVSEL#
Target
PAR
H ost Target
AD
DWORD TRANSFER
D ata D ata Active Active
IRDY#
D ata
D ata
PERR#
Target
Active
Active
SERR#
Target
Active
N ote: PER R # and SER R are optional in a bus target application. Even Parity is on AD [31:0], C /BE[3:0]#, and PAR
PC I_BR D
51
ac
DISCONTINUED
FIGURE 20. PCI BUS CLOCK
1.44 ns (max) 11 ns (min) 1.44 ns (max) 11 ns (min)
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
0.6 Vcc CLK 0.4Vcc p-to-p (minimum) 0.2Vcc Tvalid (2-11 ns)
Bused Signal Output Delay
Ton (2 ns min)
Tri-State Output
Toff (28 ns Max) Tsetup (7 ns min) Thold (0 ns)
Bused Signal Input Inputs Valid pci_clk
52
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
ac
DISCONTINUED
FIGURE 21. TRANSMIT DATA INTERRUPT AT TRIGGER LEVEL
START BIT STOP BIT
DATA BITS (5-8)
TX Data
D0
D1
D2
D3
D4
D5
D6
D7 PARITY BIT NEXT DATA START BIT
5 DATA BITS 6 DATA BITS 7 DATA BITS
TX Interrupt at Transmit Trigger Level
Set at Below Trigger Level
Clear at Above Trigger Level
BAUD RATE CLOCK of 16X or 8X
TXNOFIFO-1
FIGURE 22. RECEIVE DATA READY INTERRUPT AT TRIGGER LEVEL
START BIT
DATA BITS (5-8)
STOP BIT
RX Data Input
D0
D1
D2
D3
D4
D5
D6
D7 PARITY BIT First byte that reaches the trigger level
RX Data Ready Interrupt at Receive Trigger Level
De-asserted at below trigger level
Asserted at above trigger level
RXFIFO1
53
ac
DISCONTINUED
PACKAGE DIMENSIONS
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
100 LEAD T HIN QUAD FLAT PACK (14 x 14 x 1.0 mm, T QFP)
Rev.1.00
D D1
75
51
76
50
D1 D
1 00
26
1
25
A2 A
Seating Plane
e
B C
A1
L
S YMBOL A A1 A2 B C D D1 e L
INCHES MIN 0.039 0.002 0.037 0.007 0.004 0.622 0.547 MAX 0.047 0.006 0.041 0.011 0.008 0.638 0.555
MILLIMETERS MIN MAX 1.00 0.05 0.95 0.17 0.09 15.80 13.90 1.20 0.15 1.05 0.27 0.20 16.20 14.10
0.020 BSC 0.018 0.030
0.50 BSC 0.45 0.75 7o
0o 7o 0o Note: The control dimens ion is in millimeter.
54
ac
XR17L152 3.3V PCI BUS DUAL UART
REV. 1.1.0
DISCONTINUED
REVISION HISTORY
DATE July 2002 October 2002 August 2003 REVISION Adv. Rev. 1.0.0 Rev. 1.0.0 Rev. 1.1.0 Advanced Datasheet DESCRIPTION
Release into production. Updated DC and AC Electrical Characteristics. Added Device Status to Ordering Information. Changed status to "Discontinued." Please refer to the XR17D152 as a replacement or for new designs.
NOTICE
EXAR Corporation reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are free of patent infringement. Charts and schedules contained here in are only for illustration purposes and may vary depending upon a user's specific application. While the information in this publication has been carefully checked; no responsibility, however, is assumed for inaccuracies. EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the user assumes all such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances. Copyright 2002 EXAR Corporation Datasheet August 2003. Send your UART technical inquiry with technical details to hotline: uarttechsupport@exar.com. Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited. 55

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