Series PMC520 Octal EIA/TIA-232E Communication Module

Transcription

1 Series PMC520 Octal EIA/TIA-232E Communication Module USER S MANUAL ACROMAG INCORPORATED Tel: (248) South Wixom Road Fax: (248) P.O. BOX 437 Wixom, MI U.S.A. Copyright 2004, Acromag, Inc., Printed in the USA. Data and specifications are subject to change without notice B2D024

2 2 TABLE OF CONTENTS PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD IMPORTANT SAFETY CONSIDERATIONS You must consider the possible negative effects of power, wiring, component, sensor, or software failure in the design of any type of control or monitoring system. This is very important where property loss or human life is involved. It is important that you perform satisfactory overall system design and it is agreed between you and Acromag, that this is your responsibility. The information of this manual may change without notice. Acromag makes no warranty of any kind with regard to this material, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Further, Acromag assumes no responsibility for any errors that may appear in this manual and makes no commitment to update, or keep current, the information contained in this manual. No part of this manual may be copied or reproduced in any form without the prior written consent of Acromag, Inc..0 General Information KEY 520 FEATURES... 4 PCI INTERFACE FEATURES... 5 SIGNAL INTERFACE PRODUCTS... 5 Board DLL Control Software... 6 Board VxWORKS Software... 6 Board QNX Software PREPARATION FOR USE UNPACKING AND INSPECTION... 7 CARD CAGE CONSIDERATIONS... 7 BOARD CONFIGURATION... 7 Default Configuration... 7 Front Panel I/O... 8 Rear J4 Field I/O Connector... 9 Non-Isolation Considerations PROGRAMMING INFORMATION PCI CONFIGURATION ADDRESS SPACE... 0 PCI CONFIGURATION REGISTERS... 0 MEMORY MAP... Global Interrupt Status Register XMODE... 4 RESET... 4 Global Interrupt Enable... 4 RHR Receive Holding Register... 5 THR Receive Holding Register... 5 DLL and DLM Divisor Latch Registers... 5 IER - Interrupt Enable Register... 6 ISR - Interrupt Status Register... 7 FCR FIFO Control Register... 9 LCR Line Control Register MCR Modem Control Register... 2 LSR Line Status Register MSR Modem Status Register SCR Scratch Pad Register FCTR Feature Control Register EFR Enhanced Feature Register TXCNT Transmit FIFO Level Counter TXTRG Transmit FIFO Trigger Level RXCNT Receive FIFO Level Counter RXTRG Receive FIFO Trigger Level XCHAR Register XON/XOFF,2 Registers... 27

3 PMC520 User s Manual Read RX FIFO Register Write TX FIFO Register Read RX FIFO with Errors Register THE EFFECT OF RESET PMC520 PROGRAMMING CONSIDERATIONS FIFO Polled Mode FIFO Interrupt Mode Loopback Mode Operation Software Flow Control Hardware Flow Control... 3 Programming Example EIA/TIA-232E SERIAL COMMUNICATION BOARD TABLE OF CONTENTS THEORY OF OPERATION EIA/TIA-232E SERIAL INTERFACE PMC520 OPERATION LOGIC/POWER INTERFACE SERVICE AND REPAIR SERVICE AND REPAIR ASSISTANCE PRELIMINARY SERVICE PROCEDURE WHERE TO GET HELP SPECIFICATIONS PHYSICAL ENVIRONMENTAL UART RS-232 CHANNELS RS-232 TRANSMITTER OUTPUTS RS-232 RECEIVER INPUTS PCI LOCAL BUS INTERFACE APPENDIX CABLE: MODEL TERMINATION PANEL: MODEL DRAWINGS PMC520 BLOCK DIAGRAM PMC520 RS232 DIAGRAM CABLE (SHIELDED) TERMINATION PANEL Trademarks are the property of their respective owners. RELATED PUBLICATIONS The following datasheet provides additional information for in depth understanding of the PMC520. XR7D58 Datasheet

4 4 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD.0 GENERAL INFORMATION The PMC520 board provides eight EIA/TIA-232E serial communication channels from a single PMC socket. The transmit and receive paths of each channel include generous 64- byte FIFO buffers to minimize CPU interaction. Character size, stop bits, parity, and baud rate are software configurable. Prioritized interrupt generation is also supported for transmit, receive, line status, and data set conditions. The PMC520 utilizes state of the art Surface-Mounted Technology (SMT) to achieve its wide functionality and is an ideal choice for a wide range of industrial communication interface applications that require a highly reliable, high-performance interface at a low cost. Table.: The PMC520 boards are available in standard and extended temperature ranges Model PMC520 PMC520R PMC520E PMC520RE Board Form Factor PCI Mezzanine Card PCI Mezzanine Card (Rear I/O) PCI Mezzanine Card PCI Mezzanine Card (Rear I/O) Description Eight EIA/TIA-232E Channels Eight EIA/TIA-232E Channels Eight EIA/TIA-232E Channels Eight EIA/TIA-232E Channels Operating Temperature Range 0 C to +70 C 0 C to +70 C -40 C to +85 C -40 C to +85 C KEY PMC520 FEATURES High density Provides programmable control of eight EIA/TIA-232E serial channels. 64-Character FIFO Buffers - Both the transmit and receive channels of each serial port provide 64-byte data buffering to reduce CPU interactions and interrupts. This allows the external processor to handle more tasks within a given time. Programmable Character Size - Each serial port is software programmable for 5, 6, 7, or 8 bit character sizes. Programmable Stop Bits - Each serial port allows, -/2, or 2 stopbits to be added to, or deleted from, the serial data stream. Programmable Parity Generation & Detection - Even, Odd, or No Parity generation and detection is supported. Line-Break Generation & Detection - provision for sending and detecting the line break character is provided. False Start Bit Detection - Prevents the receiver from assembling false data characters due to low-going noise spikes on the RX input line. Programmable Baud Rate - The internal baud rate generator allows the 230.4K maximum baud rate to be divided by any divisor between and (2 6 ), providing support for all standard baud rates. Interrupt Support - Individually controlled transmit empty, receive ready, line status, data set, & flow control interrupts may be generated. Individual Modem Control Signals - Each serial channel includes a modem-control and modem-status register and provides EIA/TIA-232E modem line support, including RTS, CTS, DTR and DSR.

5 PMC520 User s Manual Internal Diagnostic Capabilities - Loopback controls for communication link fault isolation are included. Break, parity, overrun, and framing error simulation are also possible. EIA/TIA-232E SERIAL COMMUNICATION BOARD KEY PMC520 FEATURES 5 Compatible with Industry Standard UARTs - Each UART of this PMC module has its own 6550 UART compatible configuration register set. Software Flow Control - One or two sequential receive data characters are compared to a programmed Xon or Xoff character value. Data transmission can be suspended or resumed via software flow control. Hardware (RTS/CTS or DTR/DSR) Flow Control - The CTS/DSR signal is monitored for remote buffer overflow indication and will suspend transmissions if it becomes active. The RTS/DTR signal is used to request the remote unit to suspend/restart transmission to prevent overflow of the local FIFO. High density Single-width PMC Target module. Field Connections All eight EIA/TIA-232E serial channels connections are made through a single 68-pin SCSI-3 front panel I/O connector. Models PMC520R and PMC520RE, only use J4-64 pin rear I/O connector. PCI INTERFACE FEATURES 32, 6, 8-bit I/O - Register Read/Write is performed through data transfer cycles in the PCI memory space. All registers can be accessed via 32, 6, or 8-bit data transfers. Compatibility Complies to PCI Local Bus Specification Revision 2.3. Provides one multifunction interrupt. Universal PCI Bus buffers Auto sense 3.3V or 5V operation. Cables and a termination panel are also available to interface with this board, via the 68 pin SCSI front panel connector. Cable: Model : A 2-meter, round 68 conductor shielded cable with a male SCSI-3 connector at both ends and 34 twisted pairs. The cable is used for connecting the board to Model termination panels. For optimum performance, use the shortest possible length of shielded input cable. Termination Panel: Model : DIN-rail mountable panel provides 68 screw terminals for universal field I/O termination. Connects to Acromag board, via SCSI-3 to twisted pair cable described above. SIGNAL INTERFACE PRODUCTS See the Appendix for further information on these products.

6 6 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD BOARD DLL CONTROL SOFTWARE Acromag provides a software product (sold separately) to facilitate the development of Windows (98/Me/2000/XP ) applications accessing Acromag PMC I/O board products, PCI I/O Cards, and CompactPCI I/O Cards. This software (Model PCISW-API-WIN) consists of low-level drivers and Windows 32 Dynamic Link Libraries (DLLs) that are compatible with a number of programming environments including Visual C++, Visual Basic, Borland C++ Builder and others. The DLL functions provide a high-level interface to boards eliminating the need to perform low-level reads/writes of registers, and the writing of interrupt handlers. BOARD VxWORKS SOFTWARE Acromag provides a software product (sold separately) consisting of board VxWorks software. This software (Model PMCSW-API-VXW) is composed of VxWorks (real time operating system) libraries for all Acromag PMC I/O board products, PCI I/O Cards, and CompactPCI I/O Cards. The software is implemented as a library of C functions which link with existing user code to make possible simple control of all Acromag PMC boards. BOARD QNX SOFTWARE Acromag provides a software product (sold separately) consisting of board QNX software. This software (Model PCISW-API-QNX) is composed of QNX (real time operating system) libraries for all Acromag PMC I/O board products, PCI I/O Cards, and CompactPCI I/O Cards. The software is implemented as a library of C functions which link with existing user code to make possible simple control of all Acromag PMC boards.

7 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD Upon receipt of this product, inspect the shipping carton for evidence of mishandling during transit. If the shipping carton is badly damaged or water stained, request that the carrier's agent be present when the carton is opened. If the carrier's agent is absent when the carton is opened and the contents of the carton are damaged, keep the carton and packing material for the agent's inspection. For repairs to a product damaged in shipment, refer to the Acromag Service Policy to obtain return instructions. It is suggested that salvageable shipping cartons and packing material be saved for future use in the event the product must be shipped PREPARATION FOR USE UNPACKING AND INSPECTION This board is physically protected with packing material and electrically protected with an anti-static bag during shipment. However, it is recommended that the board be visually inspected for evidence of mishandling prior to applying power. Refer to the specifications for loading and power requirements. Be sure that the system power supplies are able to accommodate the power requirements of the carrier/cpu board, plus the installed boards, within the voltage tolerances specified. Adequate air circulation must be provided to prevent a temperature rise above the maximum operating temperature and to prolong the life of the electronics. If the installation is in an industrial environment and the board is exposed to environmental air, careful consideration should be given to airfiltering. WARNING: This board utilizes static sensitive components and should only be handled at a staticsafe workstation. CARD CAGE CONSIDERATIONS IMPORTANT: Adequate air circulation must be provided to prevent a temperature rise above the maximum operating temperature. Remove power from the system before installing board, cables, termination panels, and field wiring. The board may be configured differently, depending on the application. When the board is shipped from the factory, it is configured as follows: The default configuration of the programmable software control register bits at power-up are described in section 3. The control registers must be programmed to the desired configuration before starting data input or output operation. BOARD CONFIGURATION Default Configuration

8 8 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD Front Panel Field I/O Connector The front panel connector provides the field I/O interface connections. It is a SCSI-3 68-pin female connector (AMP or equivalent) employing latch blocks and 30 micron gold in the mating area (per MIL-G , Type II, Grade C). Connects to Acromag termination panel from the front panel via round shielded cable (Model ). All eight EIA/TIA-232E serial communication channels for interfacing are shown in table 2.. Each channel has six signals and are designated by channels 0 through channel 7. Table 2.: Board Field I/O Pin Connections The board has eight EIA/TIA- 232E serial communication channels. Pin Description Pin Pin Description Pin TX0 TX4 35 RX0 2 RX4 36 CTS0# 3 CTS4# 37 RTS0# 4 RTS4# 38 DSR0# 5 DSR4# 39 DTR0# 6 DTR4# TX 9 TX5 43 RX 0 RX5 44 CTS# CTS5# 45 RTS# 2 RTS5# 46 DSR# 3 DSR5# 47 DTR# 4 DTR5# TX2 7 TX6 5 RX2 8 RX6 52 CTS2# 9 CTS6# 53 RTS2# 20 RTS6# 54 DSR2# 2 DSR6# 55 DTR2# 22 DTR6# TX3 25 TX7 59 RX3 26 RX7 60 CTS3# 27 CTS7# 6 RTS3# 28 RTS7# 62 DSR3# 29 DSR7# 63 DTR3# 30 DTR7# COMMON 33 COMMON 67 COMMON 34 COMMON 68 A pound sign (#) is used to indicate an active-low signal.

9 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD 9 On models with rear I/O, the J4 PMC connector provides the field I/O interface connections. This connector is a 64-pin female receptacle header (AMP or equivalent) which mates to the male connector on the carrier/cpu board (AMP or equivalent). All eight EIA/TIA-232E serial communication channels for interfacing are shown in table 2.2. Each channel has six signals and are designated by channels 0 through channel 7. Pin Description Pin Pin Description Pin TX0 TX4 33 RX0 2 RX4 34 CTS0# 3 CTS4# 35 RTS0# 4 RTS4# 36 DSR0# 5 DSR4# 37 DTR0# 6 DTR4# TX 9 TX5 4 RX 0 RX5 42 CTS# CTS5# 43 RTS# 2 RTS5# 44 DSR# 3 DSR5# 45 DTR# 4 DTR5# TX2 7 TX6 49 RX2 8 RX6 50 CTS2# 9 CTS6# 5 RTS2# 20 RTS6# 52 DSR2# 2 DSR6# 53 DTR2# 22 DTR6# TX3 25 TX7 57 RX3 26 RX7 58 CTS3# 27 CTS7# 59 RTS3# 28 RTS7# 60 DSR3# 29 DSR7# 6 DTR3# 30 DTR7# 62 3 COMMON COMMON 64 A pound sign (#) is used to indicate an active-low signal. Rear J4 Field I/O Connector Table 2.2: Board Rear Field I/O Pin Connections The board has eight EIA/TIA- 232E serial communication channels. The board is non-isolated, since there is electrical continuity between the logic and field I/O grounds. As such, the field I/O connections are not isolated from the system. Care should be taken in designing installations without isolation to avoid noise pickup and ground loops caused by multiple ground connections. This is particularly important for analog inputs and outputs when a high level of accuracy/resolution is needed. Non-Isolation Considerations

10 0 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD 3.0 PROGRAMMING INFORMATION This Section provides the specific information necessary to program and operate the board. This board is a PCI Specification version 2.3 compliant PCI bus target only board. The PCI bus is defined to address three distinct address spaces: I/O, memory, and configuration space. This board can be accessed via the PCI bus memory space and configuration spaces, only. The card s configuration registers are initialized by system software at power-up to configure the card. The board is a Plug-and-Play PCI card. As a Plug-and-Play card the board s base address and system interrupt request line are not selected via jumpers but are assigned by system software upon power-up via the configuration registers. A PCI bus configuration access is used to read/write the PCI card s configuration registers. PCI Configuration Address Space When the computer is first powered-up, the computer s system configuration software scans the PCI bus to determine what PCI devices are present. The software also determines the configuration requirements of the PCI card. The system software accesses the configuration registers to determine how many blocks of memory space the carrier requires. It then programs the board s configuration registers with the unique memory base address. The configuration registers are also used to indicate that the board requires an interrupt request line. The system software then programs the configuration registers with the interrupt request line assigned to the board. Since this board is relocatable and not fixed in address space, its device driver must use the mapping information stored in the board s Configuration Space registers to determine where the board is mapped in memory space and which interrupt line will be used. PCI CONFIGURATION REGISTERS The PCI specification requires software driven initialization and configuration via the Configuration Address space. This board provides 256 bytes of configuration registers for this purpose. It contains the configuration registers, shown in Table 3., to facilitate Plug-and-Play compatibility. The Configuration Registers are accessed via the Configuration Address and Data Channels. The most important Configuration Registers are the Base Address Registers and the Interrupt Line Register which must be read to determine the base address assigned to the board and the interrupt request line that goes active on a board interrupt request.

11 PMC520 User s Manual Reg. Num. D3 D24 D23 D6 D5 D8 D7 D0 0 Device ID=0520 Vendor ID= 6D5 Status Command 2 Class Code= Rev ID=02 3 BIST Header Latency Cache 4 32-bit Memory Base Address for 4K-Byte Block 5 : 0 Not Used Subsystem ID=0520 Subsystem Vendor ID=6D5 2 Not Used 3,4 Reserved 5 Max_Lat Min_Gnt Inter. Pin Inter. Line EIA/TIA-232E SERIAL COMMUNICATION BOARD Table 3. Configuration Registers The memory space address map for the board is shown in Table 3.2. Note that the base address for the board in memory space must be added to the addresses shown to properly access the board registers. Register accesses as 32, 24, 6, and 8-bit in memory space are permitted unless otherwise specified. MEMORY MAP The memory space consists of two types of registers. The first type is the Device Configuration Registers (Table 3.3). These registers occupy 4K of memory space at Base Address + 80H and are used for general device configuration and monitoring. The second register type consists of each channel s UART configuration registers. These are used to control and monitor the status of the individual channels. D07 D00 LCR UART Channel 0 READ RHR Channel 0 - Receive Holding Register WRITE THR Channel 0 - Transmit Holding Register READ/WRITE DLL Channel 0 - Divisor Latch Low READ/WRITE DLM Channel 0 - Divisor Latch High READ/WRITE IER Channel 0 - Interrupt Enable Register READ ISR Channel 0 - Interrupt Status Register WRITE FCR Channel 0 - FIFO Control Register READ/WRITE LCR Channel 0 - Line Control Register READ/WRITE MCR Channel 0 - Modem Control Register READ LSR Channel 0 - Line Status Register Bit 7 = 0 Bit 7 = 0 Bit 7 = Bit 7 = Base Addr Table 3.2: Memory Map

12 2 MEMORY MAP PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD D07 D00 Comments READ MSR Channel 0 - Modem Status Register WRITE RS485 Channel 0 - Turn-Around Delay Register Not Supported 06 READ/WRITE SPR Channel 0 - Scratch Pad Register READ/WRITE FCTR Channel 0 Feature Control Register READ/WRITE EFR Channel 0 Enhanced Function Register READ TXCNT Channel 0 Transmit FIFO Level Counter WRITE TXTRG Channel 0 Transmit FIFO Trigger Level READ RXCNT Channel 0 Receive FIFO Level Counter WRITE RXTRG Channel 0 Receive FIFO Trigger Level WRITE Channel 0 Xoff- Xoff Character READ Channel 0 Xchar WRITE Channel 0 Xoff-2 Xoff Character 2 WRITE Channel 0 Xon- Xon Character WRITE Channel 0 Xon-2 Xon Character 2 Xon, Xoff Rcvd. Flags BASE ADDR+ Reserved 0-7F DEVICE CONFIGURATION REGISTERS See Table Reserved READ Channel 0 Read FIFO WRITE Channel 0 Write FIFO Data Width 8/6/24/32 Data Width 8/6/24/ A 0A 0B 0B 0C 0C 0D 0E 0F 94-FF 00-3F 00-3F Reserved 40-7F READ Channel 0 Read FIFO with errors UART Channel Data Width 6/32 80-FF Channel Registers F Reserved READ Channel Read FIFO Data Width 8/6/24/ FF F

13 PMC520 User s Manual D07 D00 Comments WRITE Channel Write FIFO EIA/TIA-232E SERIAL COMMUNICATION BOARD Data Width 8/6/24/32 Base Addr F Reserved F READ Channel Read FIFO with errors UART Channel 2 UART Channel 3 UART Channel 4 UART Channel 5 UART Channel 6 UART Channel 7 Data Width 6/ FF 400-5FF 600-7FF 800-9FF A00-BFF C00-DFF E00-FFF Notes (Table 3.2):. To save user manual space the registers corresponding to channels to 7 have not been individually shown. The registers of channels to 7 are in the address space shown above. To access a register in channel 7, for example, the offset of E00 hex is added to the address of the corresponding register given in table 3.2. All channels require a 52 byte memory block. MEMORY MAP 3 REGISTER Global Interrupt Status (Read-only) Timer (Read/Write) Ancillary (Read/Write) Ancillary2 (Read-only) MPIO (Read/Write) Byte 3 [3:24] Byte 2 [23:6] Byte [5:8] Byte 0 [7:0] Base Addr+ INT3 INT2 INT INT TIMER MSB SLEEP TIMER LSB RESET TIMER (reserved) REGA (reserved) TIMER CNTL XMODE 88-8B MPIOINT REGB DVID DREV 8C-8F MPIOSEL MPIOINV MPIO3T MPIOLVL Table 3.3: Device Configuration Registers shown in DWORD alignment. This memory map reflects byte accesses using the Little Endian byte ordering format. Little Endian uses even-byte addresses to store the loworder byte. The Intel x86 family of microprocessors uses Little Endian byte ordering. Big Endian is the convention used in the Motorola microprocessor family and is the VMEbus convention. In Big Endian, the lower-order byte is stored at odd-byte addresses. This board operates in two different modes. In one mode, this device remains software compatible with the industry standard 6C550 family of UART s and provides double-buffering of data registers. In the FIFO Mode (enabled via bit 0 of the FCR register), data registers are FIFO-buffered so that read and write operations can be performed while the UART is performing serial-to-parallel and parallel-to-serial conversions. Two FIFO modes are possible: FIFO Interrupt Mode and FIFO Polled Mode. Some registers operate differently between the available modes and this is noted in the following paragraphs.

14 4 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD DEVICE CONFIGURATION REGISTERS Note: Only device configuration registers that are supported by the PMC520 are described in this section. Global Interrupt Status Register (READ Only) This 32-bit wide register [INT0, INT, INT2 and INT3] provides interrupt source and type information. Each of the first 8 bits (INT0) represents a channel and indicates if that channel has requested service. For example INT0 bit-0 represents the interrupt status for channel 0 and INT0 bit-7 represents the interrupt status for channel 7. An interrupt service routine can inspect INT0 to determine that a channel requires service and then read the channel s Interrupt Status Register (ISR) to determine the source of the interrupt. INT3, INT2 and INT [3:8] provide a twenty-four bit encoded interrupt indicator. Each channel s interrupt is encoded into 3 bits for receive, transmit and status. Bits [0:8] represent channel 0, bits [3:] represent channel and so forth. The table below shows the 3 bit encoding and priority order. This interrupt source encoding provides much of the same interrupt source data that would be obtained by reading each channel s ISR. Interrupt clearing is covered in the description of the Interrupt Status Register UART Channel [7:0] Interrupt Source Encoding Priority Bit[N + 2] Bit[N + ] Bit[N + 0] Source of the Interrupt x None 0 0 RXRDY and RX Line Status RXRDY Timeout 3 0 TXRDY or THR empty 4 0 MSR, RTS/CTS or DTR/DSR delta or Xoff/Xon detected or special character detected 8XMODE (Read/Write) Each bit of this 8-bit register selects an 8X or 6X sampling rate for the corresponding UART channel. Channels 7 to 0 are configured using bits 7 to 0 respectively. Logic 0 (default) selects normal 6X sampling while logic selects 8X sampling rate. Transmit and receive data rates will double by selecting 8X. RESET (Read/Write) UART channels 7 to 0 can be reset using bits 7 to 0 respectively. After setting a bit to logic, all registers in the corresponding channel will be reset to the default condition. Each bit is self-resetting after it is written. Global Interrupt Enable (Read/Write) On the PMC520 the UART s multi-purpose input/output 0 (MPIO0) is used internally as a Global Interrupt Enable switch. In order for any UART channel interrupts to be seen by the system, the multi-purpose input/output registers must be configured as follows:. The MPIOINT, MPIO3T, and MPI03T registers should be left in their default states (all bits low). 2. The MPIOSEL register should be set to FEH (FFH is the default). This configures MPIO pin 0 as an output. 3. MPIOLVL bits 7 to should be left in their default state (low). 4. MPIOLVL bit 0 now acts as the Global Interrupt Enable bit. 0 = Disable Interrupt = Enable Interrupt

15 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD 5 RHR - Receive Holding Register, Channels 0-7 (READ Only) The Receive Holding Register (RHR) is a serial channel input data register that receives the input data from the receiver shift register and holds from 5 to 8 bits of data, as specified by the character size programmed in the Line Control Register (LCR bits 0 and ). If less than 8 bits are transmitted, then data is right-justified to the LSB. If parity is used, then LCR bit 3 (parity enable) and LCR bit 4 (type of parity) are required. Status for the receiver is provided via the Line-Status Register (LSR). When a full character is received (including parity and stop bits), the data-received indication bit (bit 0) of the LSR is set to. The host CPU then reads the Receiver Buffer Register, which resets LSR bit 0 low. If the character is not read prior to a new character transfer between the receiver shift register and the receive holding register, the overrun-error status indication is set in LSR bit. If there is a parity error, the error is indicated in LSR bit 2. If a stop bit is not detected, a framing error indication is set in bit 3 of the LSR. UART CONFIGURATION REGISTERS Serial asynchronous data is input to the receiver shift register via the receive data line. From the idle state, this line is monitored for a high-to-low transition (start bit). When the start bit is detected, an internal receiver counter starts counting at the 6x or 8x clock rate. After 8 or 4 clocks the start bit period should be at its center. The start bit is judged valid if it is still low at this point. This is known as false start-bit detection. By verifying the start bit in this manner, it helps to prevent the receiver from assembling an invalid data character due to a low-going noise spike on the receive data line. THR - Transmit Holding Register, Channels 0-7 (WRITE Only) The Transmitter Holding Register (THR) is a serial channel output data register that holds from 5 to 8 bits of data, as specified by the character size programmed in the Line Control Register. If less than 8 bits are transmitted, then data is entered right-justified to the LSB. This data is framed as required, then shifted to the transmit data line. The THR is also the input register to the transmit FIFO when FIFO operation is enabled by FCR bit-0. The status of the THR is provided in the Line Status Register (LSR). The THR empty flag in the LSR register is set to a logic when the last data byte is transferred from the THR to the transmit shift register. DLL & DLM - Divisor Latch Registers, Channels 0-7 (R/W) Each channel has its own Baud Rate Generator (BRG) with a prescaler for the transmitter and receiver. A software bit in the Modem Control Register (MCR) controls the prescaler. The MCR register bit-7 sets the prescaler to divide the MHz crystal by or 4. The output of the prescaler clocks to the BRG. The BRG further divides this clock by a programmable divisor between and 2 (6-) to obtain a 6x or 8x sampling clock of the serial data rate. Two 8-bit divisor latch registers per channel are used to store the divisors in 6-bit binary format. The DLL register stores the low-order byte of the divisor and DLM stores the high-order byte. These registers default to random values during upon power up and must be loaded during initialization. Note that bit 7 of the LCR register must first be set high to access the divisor latch registers (DLL and DLM) during a read/write operation. The relationship between the baud rate, prescaler, divisor, and the MHz clock can be summarized in the following equations:

16 6 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD Divisor = MHz 6 Baud Rate Prescaler with 8XMODE = 0 Divisor = MHz 8 Baud Rate Prescaler with 8XMODE = The Prescaler term represents the state of MCR bit-7 as follows: Prescaler = If MCR bit-7=0 Prescaler = 4 If MCR bit-7= The following table shows the correct divisor to use for generation of some standard baud rates (based on the MHz clock at 6X clock rate). Note that baud rates up to 92.6K may be configured, but the EIA/TIA-232E drivers of this module limits data rates to 230Kbps maximum for performance within rated specifications. A different external crystal can replace the MHz crystal on the circuit board to obtain unique clock rates. You may contact Acromag Applications Engineering to explore options in this area. Table 3.4: Baud Rate Divisors (4.74MHz Clock). BAUD RATE DIVISOR (N) MCR MCR Decimal DLM DLL Bit-7= Bit-7=0 (HEX) (HEX) C , , , , ,200 76, C 28,800 5, ,400 53, , , With respect to this device, the baud rate may be considered equal to the number of bits transmitted per second (bps). The bit rate (bps), or baud rate, defines the bit time. This is the length of time a bit will be held on before the next bit is transmitted. A receiver and transmitter must be communicating at the same bit rate, or data will be garbled. A receiver is alerted to an incoming character by the start bit, which marks the beginning of the character. It then times the incoming signal, sampling each bit as near to the center of the bit time as possible. IER - Interrupt Enable Register, Channels 0-7 (R/W) The Interrupt Enable Register is used to independently enable/ disable the serial channel interrupt sources. Each of the eight channels have seven unique interrupt sources which are all mapped to INTA# of the PMC module. An interrupt source is disabled by setting the corresponding IER bit to logic 0, and enabled by setting the IER bit to logic. Note that in order for channel interrupts to be seen by the system, the multi-purpose input/output registers must be configured properly (see the Global Interrupt Enable section).

17 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD 7 Interrupt Enable Register IER BIT INTERRUPT ACTION 0 RHR Interrupt Enable 0 = Disable Interrupt (default) = Enable Interrupt 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. A receive data timeout interrupt will be issued in the FIFO mode when the receive FIFO has not reached the programmed trigger level and the RX input has been idle for 4 character + 2 bit times. THR Interrupt Enable 0 = Disable Interrupt (default) = Enable Interrupt This interrupt is associated with bit-5 in the LSR register. An interrupt is issued whenever the THR becomes empty or when data in the FIFO falls below programmed trigger level. 2 Receive Line Status Interrupt Enable 0 = Disable Interrupt (default) = Enable Interrupt Any LSR register bits, 2, 3 or 4 will generate an LSR immediately when a character received in the RX FIFO has an error. 3 Modem Status Interrupt Enable 0 = Disable Interrupt (default) = Enable Interrupt 4 Reserved 5 Xoff Interrupt Enable (requires EFR bit-4=) 0 = Disable the software flow control (default) = Enable the software flow control 6 RTS#/DTR# Output Interrupt Enable (requires EFR bit-4=) 0 = Disable Interrupt (default) = Enable Interrupt. The UART issues an interrupt when the RTS#/DTR# pin makes a transition. The RTS# or DTR# output is selected via MCR bit-2. 7 CTS# /DSR# Input Interrupt Enable (requires EFR bit-4=) 0 = Disable Interrupt (default) = Enable Interrupt. The UART issues an interrupt when the CTS#/DSR# pin makes a transition. The CTS# or DSR# input is selected via MCR bit-2. A pound sign (#) is used to indicate an active-low signal on the UART pin. Note, however, that the handshake signals (RTS, CTS, DTR and DSR) are inverted prior to the field I/O interface. ISR - Interrupt Status Register, Channels 0-7 (READ Only) The Interrupt Status Register is used to indicate that a prioritized interrupt is pending and the type of interrupt that is pending. The eight individual channels share the PMC module INTA# signal. Six levels of prioritized interrupts are provided to minimize software interaction. Performing a read cycle on the ISR will provide the user with the highest pending interrupt level to be serviced. No other interrupts are acknowledged until the pending interrupt is serviced. Whenever the interrupt status register is read, the interrupt status is cleared. Note, only the current pending interrupt is cleared by the read. A lower level interrupt may be seen after re-reading the interrupt status bits.

18 8 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD The following interrupt source table shows the data values (bit 0-5) for the seven prioritized interrupt levels and the interrupt sources associated with each of these interrupt levels. Interrupt Status Register PRIORITY ISR BITS Source of the Interrupt LEVEL Bit5 to Bit LSR (Receiver Line Status Register, see LSR bits -4) 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 X None (default) Notes (Interrupt Status Register):. Bit 4 of the EFR (Enhanced Feature Register) must be set to a logic to unlock access to bits 4 and 5 of the ISR register. Note that ISR bit 0 can be used to indicate whether an interrupt is pending (bit 0 is low when interrupt is pending). ISR bits, 2, and 3 are used to indicate the source for a pending interrupt at interrupt priority levels, 2, 3, and 4. Bit 4 set indicates a Xoff/Xon or special character detected interrupt pending. Reading the XCHAR register will indicate which character (Xoff or Xon) was received last. Bit 5 indicates a pending interrupt due to a change of state on the CTS#/DSR# or RTS#/DTR# signals. Bits 6 and 7 are set to a logic 0 when the FIFOs are disabled. They are set to a logic when the FIFOs are enabled. Interrupt Clearing: LSR interrupt is cleared by a read of the LSR register RXRDY is cleared by reading data until FIFO falls below the trigger level. RXRDY Time-out is cleared by reading data until the RX FIFO is empty. TXRDY interrupt is cleared by a read of the ISR register. MSR interrupt is cleared by a read of the MSR register Xon or Xoff character interrupt is cleared by a read of the ISR register. Special character interrupt is cleared by a read of the ISR register or after the next character is received. RTS#/DTR# and CTS#/DSR# status change interrupts are cleared by a read to the MSR register.

19 PMC520 User s Manual FCR - FIFO Control Register, Channels 0-7 (WRITE Only) EIA/TIA-232E SERIAL COMMUNICATION BOARD 9 This write-only register is used to enable and clear the FIFO buffers, and set the transmit/receive FIFO trigger levels. FIFO Control Register FCR BIT FUNCTION 0 TX and RX FIFO Enable 0 = Disable the transmit and receive FIFO (default). = Enables both the Tx and Rx FIFO s. This bit must be a when other FCR bits are written to or they will not be programmed. RX FIFO Reset This bit is only active when FCR bit-0 is active. 0 = No receive FIFO reset (default). = Reset the receive FIFO pointers and FIFO level counter logic (the receive shift register is not cleared or altered). This bit will return to logic 0 after resetting the FIFO. 2 TX FIFO Reset This bit is only active when FCR bit-0 is active. 0 = No transmit FIFO reset (default). = Reset the transmit FIFO pointers and FIFO level counter logic (the transmit shift register is not cleared or altered). This bit will return to logic 0 after resetting the FIFO. 3 DMA Mode Select (DMA Not Supported) 5,4 Transmit FIFO Trigger Select These bits are used to set the trigger level for the transmit FIFO interrupt. An interrupt will be issued when the number of characters in the FIFO drops below the selected trigger level, or when the FIFO becomes empty in the case that it did not get filled over the trigger level on last reload. FCTR bits 6-7 are used to select one of four trigger tables 2. Table Bit 5 Bit 4 Trigger Level A 0 0 (default) B 0 0 C D X X Programmable

20 20 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD FCR BIT FUNCTION 7,6 Receive FIFO Trigger Select These bits are used to set the trigger level for the receiver FIFO interrupt. In FIFO mode an interrupt is generated when the number of characters in the FIFO equals the programmed trigger level. FCTR bits 6-7 are used to select one of four trigger tables 2. Table Bit 7 Bit 6 Trigger Level A (default) B C D X X Programmable Notes (FIFO Control Register):. Bits 4 and 5 are only programmable when the EFR bit 4 is set to. 2. The receiver and transmitter cannot use different trigger tables. The table selected last applies to both the RX and TX side. LCR - Line Control Register, Channels 0-7 (Read/Write) The Line Control Register is used to specify the asynchronous data communication format. The word length, the number of stop bits, and the parity are selected by writing the appropriate bits in this register. Line Control Register LCR Bit FUNCTION PROGRAMMING,0 Word Length Sel. 0 0 = 5 Data Bits (default) 0 = 6 Data Bits 0 = 7 Data Bits = 8 Data Bits 2 Stop Bit Select 0 = Stop Bit (default) =.5 Stop Bits if 5 data bits; 2 Stop Bits if 6, 7, or 8 data bits selected. 3 Parity Enable 0 = No Parity = A parity bit is generated during the transmission while the receiver checks for parity error of the data character received. 4 Parity Select 0 = ODD Parity = EVEN Parity 5 Forced Parity Select 6 Transmit Break Enable 0 = parity is not forced (default) and LCR BIT-4 = 0, parity bit is forced to a logic (MARK) for the transmit and received data. and LCR BIT-4 =, parity bit is forced to a logic 0 (SPACE) for the transmit and received data. 0 = No TX break condition (default) = Forces the transmitter output (TX) to a space, LOW, for alerting the remote receiver of a line break condition. This condition remains until disabled by setting LCR bit-6 to a logic 0.

21 PMC520 User s Manual LCR Bit FUNCTION PROGRAMMING 7 Baud Rate Divisor (DLL/DLM) Enable 0 = Data registers are selected (default). = Divisor latch registers are selected. EIA/TIA-232E SERIAL COMMUNICATION BOARD 2 A detailed discussion of word length, stop bits, parity, and the break signal is included in Section 4.0 (Theory of Operation). MCR - Modem Control Register, Channels 0-7 (R/W) The Modem Control register is used for controlling the modem interface signals or general purpose inputs/outputs. Modem Control Register MCR Bit FUNCTION PROGRAMMING 0 DTR# Pins 0 = Force DTR# output HIGH (default). = Force DTR# output LOW The DTR# pin may be used for automatic hardware flow control if enabled by EFR bit-6 and MCR bit-2 =. If the modem interface is not used, this output may be used for general purpose. RTS# Pins 0 = Force RTS# output HIGH (default) = Force RTS# output LOW The RTS# pin may be used for automatic hardware flow control if 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. 2 DTR# or RTS# for Auto Flow Control 0 = Uses RTS# and CTS # pins for auto hardware flow control. = Uses DTR# and DSR # pins for auto hardware flow control. This bit is only in effect when auto RTS/DTR is enabled by EFR bit-6 3 (OP2) OP2 is not available 4 Internal Loopback Enable 5 2 Xon-Any Enable 6 Infrared Encoder/ Decoder Enable 7 2 Clock Prescaler Select 0 = Disabled internal loopback mode (default) = Enabled internal loopback mode 0 = Disable Xon-Any function (default) = Enable any Xon-any function. In this mode any RX character received will enable Xon, resume data transmission. Infrared mode is not supported 0 = Divide by one. The input clock from the crystal is fed directly to the Programmable Baud Rate Generator without further modifications, i.e., divide by one (default) = Divide by four. The prescaler divides the input clock from the crystal by four and feeds it to the Programmable Baud Rate Generator, hence, data rates become one-forth.

22 22 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD Notes (Modem Control Register):. MCR Bit 4 provides a local loopback feature for diagnostic testing of the UART channel. All UART functions operate normally. Transmit data from the transmit shift register is internally routed to the receive shift register input allowing the system to receive the same data that it was sending. The TX, RTS# and DTR# pins are held de-asserted, and the CTS# and DSR# inputs are ignored. 2. Bits 5-7 are only programmable when the EFR bit 4 is set to. The programmed values for these bits are latched when EFR bit 4 is cleared, preventing existing software from inadvertently overwriting the extended functions LSR - Line Status Register, Channels 0-7 (Read/Write-Restricted) The Line Status Register (LSR) provides the status of data transfers between the UART and the host. If IER bit-2 is set to a logic, an LSR interrupt will be generated immediately when any character in the RX FIFO has an error (parity, framing, overrun, break). Reading LSR will clear LSR bits -4. Line Status Register LSR Bit FUNCTION PROGRAMMING 0 Receive Data Ready Indicator Receiver Overrun Flag 2 Receive Data Parity Error Flag 3 Receive Data Framing Error Tag 4 Receive Break Tag 0 = No data in the receive holding register or FIFO (default). = Data has been received and is saved in the receive holding register or FIFO. 0 = No overrun error (default). = 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. This bit is cleared after LSR is read. 0 = No parity error (default). = Parity error. The received character in the RHR does not have the correct parity information and is suspect. This error is associated with the character available for reading in RHR. This bit is cleared after LSR is read. 0 = No framing error (default). = 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. This bit is cleared after LSR is read. 0 = No break condition (default). = The receiver received a break signal (RX was a logic 0 for one character frame time). In FIFO mode, only one break character is loaded into the FIFO. This bit is cleared after LSR is read.

23 PMC520 User s Manual LSR Bit FUNCTION PROGRAMMING 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 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 FIFO mode this bit is set when the transmit FIFO is empty; it is cleared when at 6 Transmit Shift Register Empty Flag 7 Receiver FIFO Data Error Flag EIA/TIA-232E SERIAL COMMUNICATION BOARD least byte is written to the transmit FIFO. This bit is the Transmit Shift Register Empty indicator. This bit is set to a logic whenever the transmitter goes idle. It is set to logic 0 whenever the THR or TSR contains the data character. In FIFO mode this bit is set to whenever the transmit FIFO and transmit shift register are both empty. 0 = No FIFO error (default). = 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. 23 MSR - Modem Status Register, Channels 0-7 (Read- Only) The Modem Status Register (MSR) provides the host CPU with an indication on the status of the modem input lines from a modem or other peripheral device. This register allows the current state of CTS and DSR to be read and provides indication of whether the state of these lines has changed since the last read of the MSR. Modem Status Register MSR Bit FUNCTION PROGRAMMING 0 Delta CTS# 0 = No Change on CTS# input (default) Input Flag = The CTS# input has changed state since the last time it was monitored. A modem status interrupt will be generated if MSR Delta DSR# Input Flag 2 Delta RI# Input Flag 3 Delta CD# Input Flag 4 CTS Input Status interrupt is enabled (IER bit-3) 0 = No Change on DSR# input (default) = 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) RI Not Supported. CD - Not Supported 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 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. If automatic hardware flow control is not used, MSR bit-4 is the compliment of the CTS# input.

24 24 PMC520 User s Manual EIA/TIA-232E SERIAL COMMUNICATION BOARD MSR Bit FUNCTION PROGRAMMING 5 DSR Input Status DSR# pin may function as automatic hardware flow control signal input if it is enabled and selected by Auto DSR (EFR bit-7) and DTR/DSR flow control select (MCR bit-2). Auto DSR flow control allows starting and stopping of local data transmissions based on the modem DSR # signal. A logic on the DSR # pin will stop the UART transmitter as soon as the current character has finished transmission, and a logic 0 will resume data transmission. If automatic hardware flow control is not used, MSR bit-5 is the compliment of the DSR # input. 6 RI Input RI - Not Supported Status 7 CD Input Status CD - Not Supported Note that not all UART signal paths are used by this model and their corresponding UART pins are tied high (+5V). This includes, RI (Ring Indicator) and CD (Carrier Detect). SCR - Scratch Pad Register, Channels 0-7 (Read/Write) This 8-bit read/write register has no effect on the operation of either serial channel. It is provided as an aide to the programmer to temporarily hold data. FCTR Feature Control Register, Channels 0-7 (Read/Write) Feature Control Register FCTR Bit FUNCTION 3:0 Auto RTS/DTR Flow Control Hysteresis Select. 4 Infrared RX Input Logic Select 5 Auto RS485 Enable PROGRAMMING When Trigger Table-D is selected, these bits select the auto RTS/DTR flow control hysteresis. The RTS/DTR hysteresis is referenced to the RX FIFO trigger level FCTR [3:0] RTS/DTR Hysteresis (characters) ± ± 6 00 ± ± 8 00 ± 6 00 ± 24 0 ± ± 2 0 ± 20 0 ± 28 ± ± ± ± 48 0 ± 52 Not supported Not supported

25 PMC520 User s Manual FCTR FUNCTION Bit 7:6 TX and RX FIFO Trigger Table Select PROGRAMMING 00 = Table A 0 = Table B 0 = Table C = Table D EIA/TIA-232E SERIAL COMMUNICATION BOARD 25 When table A, B, or C is selected the auto RTS flow control trigger is set to next FIFO trigger level for compatibility to ST6C550 and ST6C650 series. RTS#/DTR# triggers on the next level of the RX FIFO trigger level (one FIFO level above and one FIFO level below). For example, if Table C is used on the receiver with RX FIFO trigger level set to 56 bytes, RTS#/DTR# output will deassert at 60 and re-assert when the level drops below 6. EFR - Enhanced Feature Register, Channels 0-7 (Read/Write) The Enhanced Feature register is used to enable or disable the enhanced features (software flow control, and hardware flow control). This register is also used to unlock access to programming the extended register functionality of IER bits 4-7, ISR bits 4-5, FCR bits 4-5, and MCR bits 5-7. Enhanced Feature Register EFR Bit FUNCTION PROGRAMMING 3:0 Software Flow Control 00XX = No Transmit Flow Control 0XX = Transmit Xon/Xoff 0XX = Transmit Xon2/Xoff2 XX = Transmit Xon and Xon2, Xoff and Xoff2 XX00 = No receive Flow Control XX0 = Receiver Compares Xon/Xoff XX0 = Receiver Compares Xon2/Xoff2 0 = Transmit Xon/Xoff, Receiver compares Xon and Xon2, Xoff and Xoff2. 0 = Transmit Xon2/Xoff2. Receiver compares Xon and Xon2, Xoff and Xoff2. = Transmit Xon and Xon2, Xoff and Xoff2; Receiver compares Xon and Xon2, Xoff and Xoff2. 00 = No transmit flow control. Receiver compares Xon and Xon2, Xoff and Xoff2. 4 Enhanced Function Control 0 = Disable and latch the enhanced functions: the IER bits 4-7, ISR bits 4-5, FCR bits 4-5, MCR bits 5-7 (default). This feature prevents existing software from altering or overwriting the enhanced functions. = Enables the enhanced functions. Allows the IER bits 4-7, ISR bits 4-5, FCR bits 4-5, and MCR bits 5-7 to be modified.