OXFORD SEMICONDUCTOR OX16PCI954 evaluation board user guide
Contents
1. Intel Motorola Mode Motorola typelocalbus Motorola typelocalbus local bus Intel Intel type local bus as supplied local bus as Intel type local bus as supplied RS 422 Enable Enable RS422 line drivers as supplied Disable RS 422 line drivers Always short Do not open the connection Model Mode 1 21 Mode 1 0 as supplied Modeo Mode 0 1 Mode 0 0 as supplied PCI FIFOSEL PCI UART has 128 byte deep FIFOs as supplied PCI UART has 16 byte deep FIFOs Note The combined effect of these pin settings determines the operational mode of the evaluation board see Chapter 3 Configuring the Evaluation Board for further details 6 External Free Release UG 0011 J an 05 OX16PCI954 Evaluation Board User Guide Evaluation Board Features UG 0011 J an 05 JP6LK1 Figure 3 shows JP6 LK1 which is the 5x2 DTR DSR header for RS422 channels on the evaluation board The OX16PCI954 evaluation board supports two RS422 ports Data transfer rates are much greater using R5422 protocol because it uses differential signalling However RS422 connectors only allow for CTS RIS flow control JP6 LK1 provides access to the hardware lines necessary to provide DTR DSR flow control in addition to conventional CTS RTS flow control Figure 4 JP6 LK1 DTR2 DTR2 DTR3 DTR3 NC 1 DSR2 0 DSR2 O GND O DSR3 O DSR3 O O O O O O R5422 connection via a 9 way D connector is documented in Appendix B2. SEMICONDUCTOR Preface The OX16PCI954 evaluation board provides an environment in which the various modes and features of the OX16PCI954 device can be demonstrated This guide documents the board and explains how to use it to develop systems using the Oxford Semiconductor OX16PCI954 device It is relevant to developers working on implementations using those products and should be read before using it to avoid the possibility of usage errors This manual assumes that you understand the capabilities of Oxtord Semiconductor UART products and are familiar with PCI and PC card bus interfaces Revis ion Table I documents the revisions of this manual Information Table Revision Information Reison Modification O January 2005 First publication in revised house style Typog raph iC In this manual the conventions listed in Table II apply Conventions Table Il Typographic Conventions N EE EEN y Italic Letters With Initial Capital Letters A cross reference to another publication Software code or text typed in via a keyboard Bold Letters A program function class or method A numbered list where the order of list items is significant me A list where the order of items is not significant Cross refers to another section within the document Significant additional information UG 0011 J an 05 External Free Release V Preface OX16PCI954 Evaluation Board User Guide P roduct The order code for the OX1
3. 0 must be set to 00 E Plug the OX16C954 device into IC1 For the PCI UARTs and the local bus UARTs channels 0 and 1 interface via RS232 connections and channels 2 and 3 interface via RS422 connections The RS422 ports apply flow control using DTR and DSR signals that are enabled via JP6 LK1 Although it is possible to obtain basic hardware flow control without DTR and DSR they are essential for DTR DSR flow control or isochronous mode operation An extra cable is needed to use DTR DSR and is implemented as follows E Connect the extra 37 way D type connector to JP1 m If required enable the R5422 channels fit R5422 Enable on JP6 LK1 The following jumpers on JP6 LK1 can be fitted as required Quad FIFO Select INTEN Intel Motorola Mode PCI FIFO Select External Free Release UG 0011 J an 05 OX16PCI954 Evaluation Board User Guide Configuring the Evaluation Board Implementing Mode 01 Quad UART Parallel Port In quad UART parallel port mode four internal UARTs are provided using the OX16PCI954 and the parallel port header is used The key settings for implementing this mode are listed below E Mode pins 1 0 must be set to 01 S Remove the OX16C954 device from IC1 LI Connect the parallel port header to P4 For the PCI UARTS channels 0 and 1 interface via RS232 connections and channels 2 and 3 interface via R5422 connections The R5422 ports apply flow control using DTR and DSR signals that are enabled via JP6 LK1 A
4. DEV 950B ExcludeFromSelect PCINVEN 1415 amp DEV 8401 ExcludeFromSelect PCINVEN 1415 amp DEV 9512 ExcludeFromSelect PCINVEN 1415 amp DEV 9510 ExcludeFromSelect PCMCIAXPC CARD GENERIC 1748 Manufacturer mfg mfg List of available devices mfg PCINVEN 1415 amp DEV 9501 DeviceDesc PCI 9501 PCINVEN 1415 amp DEV 9501 PCINVEN 1415 amp DEV 9511 DeviceDesc PCI 9511 PCINVEN 1415 amp DEV 9511 PCINVEN 1415 amp DEV 950A DeviceDesc PCI 950A PCINVEN 1415 amp DEV 950A PCIVVEN 1415 amp DEV 950B DeviceDesc PCI 950B PCINVEN 1415 amp DEV 950B PCIVVEN 1415 amp DEV 8401 DeviceDesc PCI 8401 PCINVEN 1415 amp DEV 8401 PCINVEN 1415 amp DEV 9521 DeviceDesc PCI 9521 PCINVEN 1415 amp DEV 9521 PCINVEN 1415 amp DEV 9512 DeviceDesc PCT NULL PCINVEN 1415 amp DEV 9512 PCINVEN 1415 amp DEV 9500 DeviceDesc PCI NULL PCINVEN 1415 amp DEV 9500 PCINVEN 1415 amp DEV 9510 DeviceDesc PCI NULL PCINVEN 1415 amp DEV 9510 CardO0 DeviceDesc CF 950 PCMCIANPC CARD GENERIC 1748 If changes are made to the vendor and subsystem id then these will have to be changed in the appropriate inf files for a driver to be loaded The Oxford Semiconductor NT driver does notsupport 15M OxP rom does not work in NT Source code is available subject to NDA External Free Release 35 Troubleshooting OX16PCI954 Evaluation Board User Guide Table 12 Driver Issues Sheet 3 of 3 Error message The clock for Systems that use 16 bit
5. OxProm Bit 2 of the OX16PCI954 local configuration amp control register LCC enables the UART clock output which is by default low When this bit is set the buffered UART clock output pin UART CLK Out is active otherwise it is permanently low and must be enabled To enable the UART clock output the device must be fitted with an EEPROM and programmed using OxProm Specifically the check box Enable UART Clock Out in zone 1 must be checked This means that a single oscillator can be used to drive serial ports on the local bus as well as the internal UARTS See the Oxford Semiconductor OxProm EEPROM Programming User Guide for details of how to use OxProm The device operational mode determines which driver is loaded For detailed instructions on how to install the reference drivers see Drivers on page 11 External Free Release 15 Configuring the Evaluation Board OX16PCI954 Evaluation Board User Guide 16 This page is intentionally blank External Free Release UG 0011 an 05 OXFORD l SEMICONDUCTOR Drivers Reference drivers and utilities for the Oxford Semiconductor UART products are supplied to demonstrate functionality under Windows operating systems These drivers have been tested using Oxford Semiconductor development boards in a range of PC systems M Driver software and any accompanying files are provided as is and without warranties as to performance or merchantability or any other warranties wh
6. UG 0011 J an 05 External Free Release 9 Evaluation Board Features OX16PCI954 Evaluation Board User Guide M The pin allocation is also the same for the PCI internal UARTs and the four ports from the OX16C954 local bus device JP1 amp JP7 On the evaluation board JP1 is a header used to access the external UART serial ports The pin allocations are the same as for the 37 way D connector in Table 4 JP7 is used for a parallel port connection External Free Release UG 0011 Jan 05 OXFORD SEMICONDUCTOR Chapter 3 Configuring the Evaluation Board The OX16PCI954 evaluation board can be used to verify a variety of system designs because it can be configured to work in different device modes The mode depends on the mode pin settings on the board each mode enables a specific combination of UART and or bridge functions In addition to the mode pins other jumpers enable and disable device features such as clock selection and interrupts which further refine the behavior of the evaluation board The configuration process determines which driver is used to operate a configured device using a system of unique vendor and subsystem IDs to differentiate modes The IDs used for the primary device modes covered in this chapter are hard coded and should not be changed however the OX16PCI954 is very flexible and can be used for other solutions which also require unique IDs Appendix C Customizing the Device Vendor ID amp Subsyst
7. 0 PCI UART RIO Open as supplied Note 1 If this is fitted a TTL crystal oscillator must be connected to JS1 2 If this is used MIOO must be reconfigured in LCC otherwise an interrupt is constantly present on function 0 UG 0011 J an 05 External Free Release 5 Evaluation Board Features OX16PCI954 Evaluation Board User Guide Headers amp The OX16PCI954 evaluation board has the following headers and C onnec to rs connectors JP3 configuration header JP6 LK1 DTR DSR header for RS422 channels JDH1 test header P2 37 way D type connector JP1 header giving access to the external UART serial ports JP7 parallel port header J P3 Figure 3 shows JP3 the 10x2 configuration header on the evaluation board Figure 3 JP3 Configuration Header Quad FIFO Select NC NC INTEN Intel Motorola Mode RS422 Enable NC Mode1 Mode 0 PCI FIFOSEL O O O O O O O O O O GO GO GOGO GO O O O O O Table 2 lists the pins on JP3 and explains their use Table 2 J P3 Settings External FIFOSEL External UART has 128 byte deep FIFOs as External UART has 16 byte deep FIFOs supplied LPTBUF Parallel port transceiver disabled as supplied Parallel port transceiver enabled Low Power Enable Allow driver to shut down the RS 232 line drivers RS 232 line drivers always enabled as supplied INTEN External UART interrupts enabled as supplied External UART interrupt enables depend on MCR 3
8. 2 as there are no internal pull ups recommend for STB AFD INIT and SLIN What does mode 10 do In mode 10 each has 16 pins corresponding to it which allows you to set these values in hardware Mode 10 provides a quad speed UART but instead of the parallel port or local bus it has the facility to set Subsystem ID and Vendor ID This mode allows manufacturers who do not require the parallel port or local bus to set the Subsystem ID and subsystem vendor ID without an EEPROM Why use the 220 k Q 470 Q The feedback resistor is used to add stability because itis being used for a wider range of 68 pf 22 pf configuration forthe frequencies than specified crystal oscillator Crystal Oscillator Circuit The OX16P C1954 provides the XTLO output pin to drive a crystal oscillator circuit The circuit is shown below with suggested component values Owing to the nature of such circuits some variation in values may be required to ensure stable oscillation at different frequencies The total load capacitance C1 and C2 in series however should be approximately that stated by the crystal manufacturer nominally 16pF Frequency Range MHz C1 pF C pF Ry Q R Q 1 8432 8 68 22 220k 470R 8 60 33 68 33 68 220K 2M2 470R Note For better stability use a smaller value of R4 Increase R to reduce power consumption The total capacitive load C1 in series with C2 should be that specified by the crystal manufacturer nominally 16pF If part
9. 6PCI954 evaluation board is EV OX16PCI954 Details C ontacting Oxford Semiconductor contact details Oxfo rd Oxford Semiconductor Ltd Semiconductor 25 Milton Park Abingdon Oxfordshire OX14 4SH United Kingdom Website http www oxsemi com Telephone 44 0 1235 824900 Fax 44 0 1235 821141 Email sales oxsemi com Alternatively you can contact your local representative vi External Free Release UG 0011 J an 05 OXFORD SEMICONDUCTOR Chapter 1 Evaluation Board Overview The OX16PCI954 evaluation board kit contains the following items E OXI16PCI954 evaluation board 5 V input with embedded OX16PCI954 amp additional OX16C954 chip Octopus 8 or 4 way serial cable Parallel port cable Additional serial port cable expander Board documentation standard configuration files and utility tools such as OxProm are available from the Oxford Semiconductor website Features The evaluation board is an adaptable tool with configurable features including the following H 4 x OX16C954 UARTS 2xRS232 2xR5422 accessible via a standard 37 way D type interface E 8 bit local bus function to drive an external OX16C954 UART 2xRS232 2xRS422 from a similar interface 3 Parallel port function via a standard 25 way D type header Serial EEPROM socket for maximum device configurability Internal crystal oscillator or any frequency via a TTL oscillator socket switchable the external OX16C954 can be driven either
10. CI954 Evaluation Board User Guide Using the Serial Driver The serial drivers are highly configurable They make use of a number of enhanced features for the Oxford Semiconductor 950 series UARTs This section describes the configuration utilities that can be used to enable and configure driver features It assumes that you are using a Win 2K or Windows XP operating system However Oxford Semiconductor also provides additional drivers for the OX16PCI954 as follows 3 Drivers for Win 9x and Windows ME which are similar to Win 2K and Windows XP drivers LI Win NT4 driver which is a single non Plug and Play driver with limited configuration options For further details about any of these drivers contact Oxford Semiconductor The driver automatically installs the correct number of serial ports to which the Windows operating system assigns COM numbers e g COMBS You can then attach modems etc to the ports and use them in the same way as any other generic port However extra configuration options are available in addition to the standard settings tab supplied with generic drivers Follow the steps below to adjust the UART serial parameters 1 Display the Control Panel and select the device manager if nec essary consult the Windows help facility for details of how to do this 2 Ensure that the Devices by type viewing option is selected 3 Click the by Ports COM amp LPT to review the installed PCI COM ports 4 D
11. DLLs cannot auto detect clock speeds for COM ports gt 8 It is COM9 was not detected default necessary to select the device speed manually in Device Manager under Data Rates to 1843200 Hz appears Do the drivers support 4 x PCI Yes cards Ports are not installed correctly 1 Check that the driver binaries are present in winntisystem32 drivers in Windows 2000 2 Check one of the settings FIFO or data rate tabs if it can see the UART it should identify the device in the top right 3 If the development board is not being used the UARTs may have mapped to different memory addresses Recompile oxmfuf sys to use I O mapping it will be a bit slower but does not have to work out the memory base address Table 13 Hardware Issues Sheet 1 of 2 Want to use the device from 4 4 Forthe supply voltage there is an approximate scaling factor although this is not linear to 5 5 volts What are the The data sheet is specified for the worst case i e 4 75 volts characteristics of the device Kv 5 00 V 21 0 over this temp range Kv 4 75 V 2 1 04 Kv 4 5 V 2 1 07 where Kv equates to degrees Kelvin The process is specified from 4 5 to 5 5 volts At 4 4 volts the scaling factor is about 1 1 so the worst case delays are around 1 1 1 04 x the original delay How do I reduce the quiescent To reduce the quiescent current tie all pins as internal pull ups and downs as given in the current during standby data sheet Oscillator leakage figures are n
12. E EI EE RO ER N OE 5 Headers amp Connectors lille 6 Chapter 3 Configuring the Evaluation Board LL 11 Bied vee ART EE OER ER EE OE EE ER OE EE ead oe bees 12 EEPROM Configuration Using OxProm 0 SS SE SS SS ee 14 NMIOIOICIAIMIOGS sarie ae tah ow hot on ou wad ee daa MOE aces hae wee we 14 Selecting Clocks SESSE ES SE eee ee eee teens 15 BARE AE OE ape EE N L EE EE eh he bee 15 UG 0011 J an 05 External Free Release ii Contents OX16PCI954 Evaluation Board User Guide Appendix A DTIVerS D N ER ER TR ER ER EE 17 Bi dade es ME EE N EO El 11 EN EE 17 Using the Serial Driver SS SE SS ES SS ee Se ee ee ee ee ee 18 Using the Parallel Port Driver SS ES SE SS ES EE BIB 20 Appendix B RS422 amp RS232 Connector Pin Assignment 23 RS422 Connector Pins SEE ee eee ee se 23 RS232 Connector Pins SEE SS eee eens 23 DB9 to DB25 Converter SEE SEE ene eee tees 24 RS232 Loop Back Test Plugs SE EE ESE SE SE eee 25 RS232 Null Modem Cables EE ES EE ES EE eee ee se 26 Fi MONIOrCaDIG se aur EER 9x MEE d eed tal ME R EN X XE UE Ed odi de WE 20 3 27 Appendix C Customizing the Device Vendor ID amp Subsystem ID 29 eu EA N EE RO RE e EO ON EE 29 Ee SARTRE TE EE nee EE EE OE EE NEE es ee 30 Appendix D Troubleshooting ss e x lt x e EER EER EE RR REK RE RR EER Re 33 IV External Free Release UG 0011 J an 05 OXFORD
13. However because most communication software works in half duplex mode this problem does not arise External Free Release UG 0011 J an 05 OXFORD Customizing the Device SEMICONDUCTOR Vendor ID amp Subsystem ID This appendix outlines recommended procedures for reconfiguring the hardware drivers to identify custom add in card configurations Overview The default vendor ID and device ID are usually acceptable for most serial and parallel port applications However designers using a device for another purpose must change the following identification fields in the PCI configuration space Vendor ID Device ID Subsystem Vendor ID Subsystem ID By doing this Plug and Play systems can differentiate between boards even when they use the same chip and load the correct drivers Three approaches can be used to identity an add in card uniquely They are all satisfactory but are listed below in order of preference 1 Obtain a vendor ID from the PCI special interest group PCISIG amp use OxProm to reprogram the vendor ID amp subsystem vendor ID fields with the new value then choose a device ID amp subsystem ID 2 Leave the vendor ID amp device ID as the Oxford Semiconductor default values Obtain a subsystem vendor ID from the PCISIG amp use OxProm to reprogram the subsystem vendor ID fields with the new value then choose the subsystem ID M Older versions of Windows e g Windows 95 or Win NT do not support this f
14. L L L L L L L This appendix discusses the use of RS422 and RS232 9 pin and 25 pin connectors in systems using the device evaluation board RS422 Figure 4 shows how R5422 ports are connected on 9 way D connectors Connector Figure 4 RS422 Pin Assignments Pins Data transfer rates are much greater using R5422 protocol because it uses differential signalling However RS422 connectors only allow for CTS RTS flow control RS232 Although the RS232 interface is differential the receive and transmit Connector pins each have their own floating ground level it is possible to connect RS232 compatible devices with this interface Pins N The convention for the R 232 diagrams below is to show signals common to both connector types in black Signals only present on the larger connector are shown in grey N The protective ground is assigned to a pin at the large connector where the connector outside is used for that purpose in the DB9 connector Figure 5 on page 18 shows the R5232 DB9 pin assignment UG 0011 J an 05 External Free Release 17 RS422 amp RS232 Connector Pin Assignment OX16PCI954 Evaluation Board User Guide Figure 5 RS232 DB 9 Pin Assignment Data Carrier Detect Data Set ready Receive Data Request to Send Transmit Data Clear to Send Data Terminator Ready Ring Indicator Signal Ground Protective Ground Figure 6 shows the RS232 DB 25 pin assignment Figure 6 RS232 DB 25 Pin Assi
15. R5422 amp R5232 Connector Pin Assignment J DH1 Figure 5 shows JDH1 which is the test header on the evaluation board All non PCI pins can be accessed from this header Figure 5 JDH1 1 32 A eo000000000000000000000000000000 B 00000000000000000000000000000000 c e0000000000000000000000000000000 Table 3 on page 8 lists the pin allocations on JDH1 External Free Release 7 Evaluation Board Features OX16PCI954 Evaluation Board User Guide Table 3 P1 Pin Allocations Pin No Row A MIO 0 MIO 3 MIO 4 MIO 5 MIO 6 MIO 7 LBRST PE BUSY ACK SLCT ERR LBCSO LBCS1 LBCS2 LBCS3 LBRD LBWR GND GND LBCLK GND LO 1 CO OO OT BUL N SLIN INIT AFD m STB GND LBDOUT HE H LBDO LBD1 LBD2 KA N9 LBD3 GND LBD4 m CO LBD5 LBD6 LBD7 UART Cik SIN1 DSR1 SING FIFOSEL TEST P2 On the evaluation board P2 is a 37 way D type connector which is used to access the PCI UART serial ports Table 4 on page 9 lists the pin allocations on the connector External Free Release UG 0011 J an 05 OX16PCI954 Evaluation Board User Guide Evaluation Board Features Table 4 37 Way D Type Connector Pins Port Number 37 Way D Type 9 Way D Type Description Type Pin No Pin No 3 8 68 OCs 4 9
16. UG 0011 Jan 05 OX16PClI954 Evaluation Board User Guide Oxford Semiconductor Limited 25 Milton Park Abingdon Oxfordshire 0X14 4SH UK 44 1235 824900 http www oxsemi com OX16PCI954 Evaluation Board User Guide All trademarks are the property of their respective owners Oxford Semiconductor Limited 2005 The content of this manual is furnished for informational use only is subject to change without notice and should not be construed as a commitment by Oxford Semiconductor Limited Oxford Semiconductor Limited assumes no responsibility or liability for any errors or inaccuracies that may appear in this book External Free Release UG 0011 J an 05 L L L N Nm NUN z LLLL EE EL LLL r OXFORD SEMICONDUCTOR Contents L L CONICS RR det ee EE OE OE EE ER NEE EE ER Ee beware iii PUCIAGE ep ML EA ET OE we OO OE EA N ge x V Revision Information anaana Es ESE eee eee teen se es ee V Typographic Conventions EE ESE SE SE ESE SE es rn V Need pT vi Contacting Oxford Semiconductor lille Ee se ee vi Chapter 1 Evaluation Board Overview ee ER EE ER ee Ee 1 xri mie Bie Baw ag wie Bie Dat RE Win ARE AD EED DR Ni Hie ed Hs ERS Be Be 1 COMIGUIAIION OE AE N EE EN OE EE N EE R dees 2 BN Mm 2 Board Layout x acc AE Dee N OE EE RU E de OR OE EE EN 3 Chapter 2 Evaluation Board Features leelr eere 5 VIS RR ORE RE EE EE N O
17. acility 3 Use the Oxford Semiconductor identification fields Oxford Semiconductor assigns a subsystem ID to the board vendor who programs the new value in using OxProm To request a subsystem ID value contact Oxford Semiconductor with a full functional description of the new add in card UG 0011 Jan 05 External Free Release 23 Customizing the Device Vendor ID amp Subsystem ID OX16PC1954 Evaluation Board User Guide The first solution is best for Windows NT systems because they do not recognize subsystem ID values Windows 2000 systems can identify different cards if oxpci inf specifies the subsystem ID values in the following format PCINVEN 1415 amp DEV 9501 amp SUBSYS 00011415 M Board vendors should not assign a new device ID or subsystem ID unless they have obtained their own vendor ID from the PCISIG Oxford Semiconductor reserves the right to refuse to allocate a subsystem ID to a board vendor Exam ples The following examples are provided for illustration only They demonstrate methods of modifying the device vendor ID and subsystem ID fields Four Serial Two Parallel Port Card For this configuration it is necessary to use the internal UARTs and have two external parallel port chips on the local bus The default ID can be used for the serial ports but there must be a different ID for the local bus The vendor can contact Oxford Semiconductor for a subsystem ID for the local bus or obtain a vendor ID and define dr
18. al Frequency to detect the input clock frequency to the UART otherwise select the frequency from the Crystal Frequency MHz drop down box For automatic crystal detection no other application can be using the port On initial entry to this dialog the Use default baud rate check box is checked unchecking it enables the following options for overriding the port configuration E Baud rate multiplier checking this box allows you to select a value from the drop down box to scale up the baud rate m Quad speed checking this box results in all application selected baud rates being multiplied by four using the OX16C954 TCR register E Baud rate divider prescaler checking this box allows you to select a value from the drop down box to scale down the selected baud rate Using the facilities in this dialog box a high speed crystal can be pre divided to generate standard baud rates or scaled up to allow higher data rates FIFOs The FIFOs dialog is used to configure 950 mode which operates with full 128 byte FIFOs fully adjustable trigger levels and thresholds for generating interrupts and applying automatic flow control This dialog can also disable the FIFOs completely although it is not recommended for normal operation Clicking the Use FIFO buffers check box enables the four sliders External Free Release 13 Drivers OX16PCI954 Evaluation Board User Guide L Using the Parallel Port Driver FIFO In
19. anager if nec essary consult the Windows help facility for details of how to do this Ensure that the Devices by type viewing option is selected Click the by Ports COM amp LPT to review the installed PCI COM ports Double click the appropriate Oxford Semiconductor PCI Parallel port to display the settings dialog for that port Click the Port Settings tab and enable or disable the interrupt as required External Free Release UG 0011 J an 05 OX16PCI954 Evaluation Board User Guide Drivers Win 9x amp Windows ME Parallel Port Configuration The parallel port driver sets the hardware to use legacy addresses 378h if available otherwise it uses the address allocated by the system BIOS Windows allocates an LPT number e g LPT2 to the port then it can be used in the same fashion as any generic parallel port Due to a contention with ISAPNP bus enumeration some systems do not work if a port uses 278h or 678h while some peripheral devices such as Zip drives do not operate correctly if the parallel port is not located at address 278h or 378h It might be necessary to experiment and move conflicting devices to another address External Free Release 15 UG 0011 Jan 05 Drivers OX16PCI954 Evaluation Board User Guide 16 This page is intentionally blank External Free Release UG 0011 an 05 L L L L OXFORD RS422 amp RS232 Connector CY SEMICONDUCTOR Pin Assignment lt L LL LL L N L
20. elease UG 0011 an 05
21. em ID outlines recommended procedures for reconfiguring the hardware drivers to identify custom add in card configurations M This chapter does not cover baud rate configuration for the device For further details of how to set the device transfer rate refer to the application note OXAN15 Setting Baud Rates Under Windows UG 0011 J an 05 External Free Release 11 Configuring the Evaluation Board OX16PCI954 Evaluation Board User Guide Device Modes Mode pins on the OX16PCI954 evaluation board select the device mode The mode pins are located on header JP6 LK1 as shown on Figure 2 on page 3 Selecting the Device Mode Table 5 shows how the mode pins are used to select the device mode Table 5 MODE Pin Settings amp Effect Mode 1 ME Ma 1 Mode 0 Quad VARTS function 0 amp 8 bit local bus function 1 Quad VARTS function 0 amp parallel port function 1 Quad VARTS function 0 amp pin assignable subsystem ID amp subsystem vendor DIL 32 bit bridge function 107 Note 1 Function is unusable because the local bus pins are used for the subsystem ID amp subsystem vendor ID 2 Only function 1 is available in this mode Implementing Mode 00 Quad UART 8 Bit Local Bus In quad UART 8 bit local bus mode four internal UARTs are provided using the OX16PCT954 and four further external UARTs are supplied using the OX16C954 The key settings for implementing this mode are listed below E Mode pins 1
22. em now picks the default settings in the driver which will not be overwritten by the contents of the EEPROM Use OXPROM to erase the EEPROM Unplug the board from the system Re solder pin 4 DO When the system has recognized the card and installed all the appropriate driver files the board can be used The EEPROM can then be reprogrammed using one of the dat files provided for the OX16PC1954 34 External Free Release UG 0011 an 05 OX16PCI954 Evaluation Board User Guide Troubleshooting Table 12 Driver Issues Sheet 2 of 3 After downloading the drivers Device not found appears on the event viewer Oxprom exe and 15M operation does not work in NT UG 0011 J an 05 This can happen if either the vendor ID or subsystem ID is changed using OXPROM which changes the contents of the EEPROM The device driver looks for these fields and does not work if they have been changed To change these fields you have to change the inf file This can come about due to changes in some of the CIS information in the EEPROM making it different from information found in the Oxpci inf file and if a parallel port is being used Oxpar inf For example the line below shows a vendor id of 1415 and no subsystem id being used ControlFlags ExcludeFromSelect PCINVEN 1415 amp DEV 9501 ExcludeFromSelect PCINVEN 1415 amp DEV 9511 ExcludeFromSelect PCINVEN 1415 amp DEV 9521 ExcludeFromSelect PCINVEN 1415 amp DEV 950A ExcludeFromSelect PCINVEN 1415 amp
23. essary to change the ID fields so that the Windows Plug and Play system can differentiate boards even though they use the same chip and load the correct driver Appendix C Customizing the Device Vendor ID amp Subsystem ID outlines recommended procedures for reconfiguring the hardware drivers to identify custom add in card configurations The drivers provided for the OX16PCI954 evaluation board have been written for Windows 2000 Windows NT and Windows XP operating systems Although drivers are also available for Linux they have not been written by Oxford Semiconductor and Oxford Semiconductor cannot be held responsible for any aspect of their performance For further information about device drivers see Drivers on page 11 External Free Release UG 0011 J an 05 OX16PCI954 Evaluation Board User Guide Evaluation Board Overview Board Layo ut Figure 1 on page 3 shows the OX16PCI954 evaluation board Figure 1 OX16PCI954 Evaluation Board n NE TIT mer baat vun 4 T 9 si dy ER l E WU I W ANY ul P jij hts ma le j Ak b yet U I MM A N IV Il WI aed E X am Lh iR 2 ad EE a u mE HARARE wia T TO Hm umb 7 RI ae d i VULTUM LI ow j Figure 2 identifies the principal features on the device Figure 2 OX16PCI954 Evaluation Board Fea
24. ether express or implied Driver Windows driver architectures are very similar utilizing Plug and Play Process bus drivers which create device objects for each available UART and parallel port New driver installation commences when the configured device is connected to the PC although subsequent actions can vary slightly depending on the operating system For Windows systems other than Windows NT4 the driver installation process is as follows 1 Each UART is hooked by a single port driver which enables the following features U 128 byte receiver amp transmitter FIFOs Adjustable receiver amp transmitter interrupt trigger level Automatic flow control Quad speed using the Times clock register TCR Flexible baud rate generation up to 15 Mbaud R5485 half duplex configuration D O D D D U Memory mapped operation Windows 2000 driver only 2 The local bus parallel port is hooked to the generic driver supplied with Windows M The drivers automatically recognize the device in any of its default or standard configurations In Plug and Play systems a wizard automatically starts up when a new device is detected to assist with device management Although it is necessary to direct the wizard to the location of the driver files the wizard handles device and driver installation automatically NM For more help with device installation see the Windows Help facility UG 0011 Jan 05 External Free Release 11 Drivers OX16P
25. from the TTL module or directly from the LB C1k Out pin of the PCI device a Isochronous mode for the internal UARTs via simple connections Test points so that signals on any bus can be observed easily UG 0011 J an 05 External Free Release 1 Evaluation Board Overview OX16PCI954 Evaluation Board User Guide Configuration Drivers The evaluation board is a valuable tool for assessing the behavior of the OX16PCI954 device and can be configured to support systems using the following selectable capabilities 8 port serial card 4 port serial 1 port parallel card E 4 port serial card with pin assignable subsystem ID amp subsystem vendor ID i 32 bit bridge Chapter 3 Configuring the Evaluation Board explains the board settings required to operate the OX16PCI954 in these modes However the flexibility of the OX16PCI954 allows users to extend the capabilities of the chip beyond its primary modes For example it is possible to use the OX16PCI954 in other solutions as follows E 4 port serial 2 port parallel card tj 2 port serial 1 port parallel card E 1 port parallel card N 4 port serial 1 port custom FPGA synchronous I O controller on the local bus The correct driver for a specific device mode is selected depending on the vendor device and subsystem IDs For the primary modes of the OX16PCI954 IDs are pre allocated and hard coded they should not be changed However for customized operational modes it is nec
26. gnment Protective Ground Transmit Data Receive Data Request to Send Clear to Send Data Set Ready Signal Ground Data Terminator Ready Data Carrier Detect Ring Indicator DB9 to DB 25 The original pin layout for RS232 was developed for a 25 pin Converter sub D connector although 9 pin connectors are commonly used In mixed applications a 9 to 25 pin converter can be used to connect connectors of different sizes as shown in Figure 7 18 External Free Release UG 0011 J an 05 OX16PCI954 Evaluation Board User Guide RS422 amp RS232 Connector Pin Assignment Figure 7 RS232 DB9 to DB25 Converter RS232 The following connectors can be used to test a PC serial port The data Loop Bac k and handshake lines are linked so that all data is sent back immediately p The PC controls its own handshaking Test Plugs Figure 8 shows a loop back that can be used to verify the serial port with standard terminal software Figure 8 RS232 Loop Back Test Plug for Terminal Emulation Software Figure 9 on page 20 can be used to test the full functionality of the serial port with Norton Diagnostics or Checklt UG 0011 J an 05 External Free Release 19 RS422 amp RS232 Connector Pin Assignment OX16PCI954 Evaluation Board User Guide RS232 Null Modem Cables 20 Figure 9 RS232 Loop Back Test Plug for Norton Diagnostics amp Checklt The easiest way of connecting two PCs is via a null modem cable altho
27. icular problems are encountered with baud rates and the use of drivers options see the application note Setting UART baud rates under Windows Does the device support D3 The device does not support D3 cold cold List specifications that the PCl interface complies with version 2 2 of the PCI Bus Specification and version 1 0 of device complies with PCI Power Management Specification INTB does not work correctly Ensure all unused MIO pins are pulled low otherwise they could generate interrupts Also ensure that MIO pins used as inputs do not have a static input i e are pulled constantly high as this causes a continuous interrupt to be generated 2 Ifa static inputis required an EEPROM should be used recommended as this allows the MIO input to be masked off disabled With my board set up for8 serial Bit 2 ofthe Local Configuration and Control register LCC offset 0x00 enables the UART ports my PC either resets or clock output When this bit is set the buffered UART clock output pin UART CLK Out is blue screens as a consequence active When low the UART CLK Outis permanently low this is the default setting and must be enabled To do this an EEPROM is required and used in conjunction with OxP rom see the OXxP rom EEPROM Programming User Guide from details UG 0011 J an 05 External Free Release 37 Troubleshooting OX16PCI954 Evaluation Board User Guide 38 This page is intentionally blank External Free R
28. ivers for the entire card The three possible approaches are given in Tables 6 to 8 Table 4 Option 1 Use the Board Vendor s Own PCI Vendor ID EN Four Serial Ports Internal UARTs Function 0 Two Parallel Ports Local Bus Function 1 Chosen by vendor Chosen by vendor Subsystem Vendor ID 0x1234 0x1234 Subsystem ID Chosen by vendor Chosen by vendor Note In this example the vendor ID is assumed to be 0x1234 In this case the devices must be identified in oxpci inf as follows PCI VEN 1234 amp DEV XXXX PCI VEN 1234 amp DEV YYYY where XXXX and YYYY are appropriate device ID for the UART Table 5 Option 2 Use the Board Vendor s Own PCI Vendor ID as the Subsystem Vendor ID N Four Serial Ports Internal UARTs Function 0 Two Parallel Ports Local Bus Function 1 Vendor ID 0x1415 default 0x1415 default 0x9501 default 0x9511 default Subsystem Vendor ID 0x1234 0x1234 S ubsystem ID Chosen by vendor Chosen by vendor Note 1 In this example the subsystem vendor ID is assumed to be 0x1234 24 External Free Release UG 0011 J an 05 OX16PCI954 Evaluation Board User Guide Customizing the Device Vendor ID amp Subsystem ID In this case the devices must be identified in oxpci inf as follows PCINVEN 1415 amp DEV 9501 amp SUBSYS XXXX1234 PCINVEN 1415 amp DEV 9511 amp SUBSYS YYYY1234 where XXXX and YYYY are appropriate device ID for the UART Table 6 Option 3 Obtain a Subsystem ID from Oxford Se
29. l without DTR and DSR they are essential for DTR DSR flow control or isochronous mode operation An extra cable is needed to use DTR DSR and is implemented as follows Li Connect the extra 37 way D type connector to JP1 E If required enable the RS422 channels fit RS422 Enable on JP6 LK1 The following jumpers on JP6 LK1 can be fitted as required External FIFO Select INTEN Intel Motorola Mode PCI FIFO Select The OX16PCI954 can be configured via a serial EEPROM if required using the Oxford Semiconductor OxProm EEPROM programming utility All features of the device can be programmed using OxProm which can be downloaded from the Oxford Semiconductor website OxProm is bundled with reference drivers sample configuration files and supporting documentation including the Oxford Semiconductor OxProm EEPROM Programming User Guide which explains how to program the OX16PCI954 using OxProm To configure the OX16PCI954 via its EEPROM plug the EEPROM into IC7 on the evaluation board If the EEPROM has not previously been programmed it presents the value OXFF when OxProm is used to program it The OX16PCT954 local bus can be used in either Intel or Motorola mode determined by the Intel Motorola link setting on JP6 LK1 When the link is not fitted the device assumes Intel mode which is the default setting To use the local bus in Motorola mode fit the Intel Motorola Mode link With the Motorola mode selection the default local bus
30. lease 25 Customizing the Device Vendor ID amp Subsystem ID OX16PCI954 Evaluation Board User Guide One Parallel Port Only lt is not possible to disable the UARTS on the device so this solution reguires the user to install a null driver for them Oxford Semiconductor has assigned a device ID for this value 0x9500 so the recommended solution is as shown in Table 5 on page 25 Table 8 One Parallel Port Only N NULL Function Function 0 One Parallel Port Local Bus Function 1 Vendor ID 0x1415 0x1415 Subsystem Vendor ID 0x1415 0x1415 Drivers recognize device ID 0x9500 as a null function and load a null driver for this device This page is intentionally blank 26 External Free Release UG 0011 an 05 OXFOAD l SEMICONDUCTOR Troubleshooting Tables 11 to 13 summarize typical difficulties and suggests ways of overcoming them Table 11 Communication Issues Sheet 1 of 2 Although the system detects the Ensure thatthe application supports COM ports other than the four legacy addresses ports a terminal application 3f8 218 3e8 2e8 If not use an application that supports all COM devices such as does not Quarterdeck P rocomm P lus or Ericom PowerTerm Some or all ports do not Ensure that the baud rates are correct The 950 series UARTs have a flexible baud communicate with other devices rate generator which can accept differing crystal frequencies pre scaler values etc The serial port configuration utility in
31. lthough it is possible to obtain basic hardware flow control without DTR and DSR they are essential for DTR DSR flow control or isochronous mode operation An extra cable is needed to use DTR DSR and is implemented as follows EJ Connect the extra 37 way D type connector to JP1 M If required enable the R5422 channels fit R5422 Enable on JP6 LK1 The following jumpers on JP6 LK1 can be fitted as required S External FIFO Select E INTEN S Intel Motorola Mode a PCI FIFO Select NM If the parallel port is recognized but will not communicate with the printer or other device check that the OX16C954 has been removed from IC1 Implementing Mode 10 Quad UART with Assignable IDs In quad UART with assignable ID mode four internal UARTSs are provided using the OX16PC1954 and the local bus pins are used to assign a subsystem ID and subsystem vendor ID The key settings for implementing this mode are listed below E Mode pins 1 0 must be set to 01 3 Remove the OX16C954 device from IC1 UG 0011 J an 05 External Free Release 13 Configuring the Evaluation Board OX16PCI954 Evaluation Board User Guide EEPROM Configuration Using OxProm Motorola Mode For the PCI UARTS channels 0 and 1 interface via RS232 connections and channels 2 and 3 interface via R5422 connections The R5422 ports apply flow control using DTR and DSR signals that are enabled via JP6 LK1 Although it is possible to obtain basic hardware flow contro
32. miconductor amp Use Other Values as Default Four serial ports internal UARTs Function 0 Two parallel ports Local bus Function 1 Vendor ID 0x1415 default 0x1415 default Device ID 0x9501 default 0x9511 default Subsystem Vendor ID 0x1415 default 0x1415 default Subsystem ID 0x0001 default Oxoor r 11 Note 1 In this example the allocated subsystem ID is assumed to be OxOOFF In this case the devices must be identified in oxpci inf as follows PCINVEN 1415 amp DEV 9501 amp SUBSYS 00011415 PCINVEN 1415 amp DEV 9511 amp SUBSYS OOFF1415 Two Serial One Parallel Port Card It is not possible to limit the hardware to enable only two serial ports so this solution requires a driver in the enumerator driver which ensures that it only registers two ports Oxford Semiconductor reserves device ID 0x950A for this so the recommended solution is as shown in Table 4 Table 7 Two Serial One Parallel Port Card Two Serial Ports Internal UARTs Function O One Parallel Port Local Bus Function 1 Vendor ID 0x1415 0x1415 S ubsystem Vendor ID 0x1415 0x1415 Driver versions 2 51 and greater associate device identity 0x950A as a two serial port device Designers should use the first two ports because they are the ones that will be used by the driver NM For Windows NT4 systems oxser inf must be modified all occurrences of 9501 must be changed to 950A before any drivers are installed UG 0011 J an 05 External Free Re
33. ot available butthis should be tied to a rail and not left floating PC will not turn off with the Apply a PME pin isolator Newer demonstration boards have this modification applied OX16P C1954 installed System doesn t detect the Close TEST link on J P6 LK1 and ensure that the MODE links are set correctly on the correct devices evaluation board The test pin must be connected to GND cannot set the RS485 driver The MCR and ACR registers are required to enable RS485 Set ACR first and then MCR enables using DTR Then the chip automatically asserts DTR to transmit At high baud rates the data 1 The application requests a port at a certain speed The driver calculates which divider throughput is very slow to use based on criteria including the crystal speed If the port speed cannot be achieved within 296 then it goes slowly The crystal must be a multiple of 1 8432 MHz 2 Firstrevision evaluation boards have transistors Q1 2 3 amp 4 just above the PCI connector Later versions have resistors in these places Which mode allows us to use Mode 00 or 01 MIO pins for our own use am not getting the correct Read this register until 2 consecutive values are the same The value can change while it number in the RFL register is being read and so will output garbage 36 External Free Release UG 0011 J an 05 OX16PCI954 Evaluation Board User Guide Troubleshooting Table 13 Hardware Issues Sheet 2 of 2 Which pull up values are 2k
34. ouble click the appropriate Oxford Semiconductor PCI COM port to display its properties dialog Three tags in the dialog are used to configure enhanced device features El Settings for standard COM port settings E Data rate advanced data rate selection options E FIFOs device mode selection and FIFO trigger level settings Settings The Settings tag groups the standard baud rate data bits parity stop bits and flow control options for standard COM port settings The settings modify the defaults used by Windows although most applications that use COM ports override the settings with their own parameters An applications baud rate is scaled up if a faster crystal is used External Free Release UG 0011 J an 05 OX16PCI954 Evaluation Board User Guide Drivers UG 0011 J an 05 This tag also allows users to select R5232 R5422 or R5485 half duplex operation The following points are worth noting for these options Ej For RS232 applications the DTR pin should be configured as normal m For R 485 the driver can configure the DTR pin as either active high or active low E DTR DSR flow control is not allowed for RS422 485 because these pins are not defined in R 422 protocols Data Rate The Data Rate dialog is used to set the clock frequency and baud rate For normal operation the serial driver generates the baud rate from the crystal frequency The baud rate can optionally be adjusted as required Click Detect Cryst
35. terrupt Transmitter levels L Transmitter a transmitter interrupt is triggered when the level of data in the transmit FIFO falls below this value Setting the trigger to zero suppresses interrupts until the transmitter is completely idle U Receiver a receiver data interrupt is triggered when the level of data in the receiver FIFO reaches this value Receiver FIFO Flow Control Thresholds DU Flow On the FIFO fill level decreases as data is read from the FIFO until it reaches this value which triggers a handshake to instruct the remote transmitter to transmit data i e it transmits an XON character to the remote machine U Flow Off the FIFO fill level increases as data is put into the FIFO until it reaches this value which triggers a handshake to instruct the remote transmitter to stop transmitting data i e it transmits an XOFF character to the remote machine The FIFO trigger levels and thresholds can be fine tuned for optimum performance In some cases a high receiver FIFO interrupt trigger level can result in the port not detecting Plug and Play serial devices This section describes the configuration utilities that can be used to enable and disable the parallel port Win 2K amp Windows XP Parallel Port Configuration Interrupts from the parallel port can be enabled and disabled using the Windows Device Manager To adjust the setting follow these steps 1 Display the Control Panel and select the Device M
36. the driver can set baud rate multipliers or override an application s baud rate setting Two of the ports on each UART chip have R S422 line drivers on the evaluation board These support higher data transfer rates but do not interface to RS232 ports Ensure that the correct ports are in use Ensure that the parallel port transceiver is disabled close LPTBUF on J P6 LK1 Ensure that the port has a clock signal either from the OX16P C1954 oscillator or from the TTL clock module This is selected with XTALsel internal UARTs and CLKsel local bus UARTs No response running a loop Ports 1 and 2 are RS232 and ports 3 and 4 are R 422 ensure that the loop back back test with a terminal set up is correct program Check that the loop back connector is wired correctly The parallel port is recognized Ensure that the parallel port transceiver is enabled if present clear LPTBUF on but does not communicate with JP6 LK1 on the evaluation board also remove the 0X16C1954 from the PLCC socket the printer or other device on the evaluation board Ensure that the device is not ECP the OXP C1954 only supports SPP and EPP drivers The local bus does not work in A connector is missing on early development boards Call Oxford Semiconductor for Motorola mode details When the board is installed ina PCI devices should be able to share interrupts but some device drivers cannot handle system it complains of a this feature If another device is using one of
37. the interrupts assigned to the OX16P C1954 resource clash try one of the following Move the OX16P C1954 board to a different P CI slot Change the system BIOS settings to allocate different resources not all BIOS s have this feature Use the serial EEPROM to allocate one interrupt to both OX16P C1954 functions Disable any non critical device using the same interrupt USB controllers sometimes cannot share resources adequately Errors are detected at baud The transmit FIFO length and receive FIFO length are set by default For lower baud rates of 300 baud and less rates the difference in length between the transmit and receive FIFOs should not exceed 123 UG 0011 J an 05 External Free Release 33 Troubleshooting OX16PCI954 Evaluation Board User Guide Table 11 Communication Issues Sheet 2 of 2 Problem Response How do support flow control To support flow control set MCR 1 and ECR 7 6 the hardware then takes care of it In addition if you set IER 7 6 the device asserts a level 6 whenever CTS and RTS toggle Table 12 Driver Issues Sheet 1 of 3 If the EEPROM is programmed To make the OS accept the card try the following with an invalid image it may not Unplug the board from the system load the driver flag an error Locate the EEPROM on the card amp unsolder pin 4 DO This will not allow the EEPROM to be interrogated by the OS as the data out line is effectively disconnected Plug the board back in The syst
38. timing values should be changed in the local control amp configuration LCC registers as follows Read not write de assertion 4 Read data strobe assertion 1 Write data strobe assertion 1 Write data strobe de assertion 3 External Free Release UG 0011 J an 05 OX16PCI954 Evaluation Board User Guide Configuring the Evaluation Board Selecting Clocks Drivers UG 0011 J an 05 Also MIO 8 in the MIO configuration registers should be configured as an inverting input and MIO 9 11 should be masked off OxProm can be used to configure these register settings alternatively an EEPROM configuration file containing these settings motorola dat is provided for this purpose An external clock must always be connected to XT1 for the PCI UARTS Either an internal crystal oscillator or a TTL oscillator module can be used the XTALsel jumper setting specifies the type of oscillator supplied See Chapter 2 Evaluation Board Features for more about this jumper setting An additional clock supply is required for the external UARTS on the OX16C954 device either the TTL oscillator module which must be fitted or the OX16PCI954 LB C1k Out The CLKsel link must be fitted to select the appropriate clock which must also be enabled or disabled by writing to the configuration register The configuration register can either be updated temporarily using the Microsoft Debug utility or permanently by programming the serial EEPROM using
39. tures 1 JDH1 Test Pin Header IC1 External OX16C954 JS1 Crystal Oscillator Socket JP4 CLKsel JP5 RIO link I JP1 Parallel Port Serial Ports U1 JP2 XTALsel OX16PCI954 JP1 External OX16C954 Oooooooooo oooooooooo m O DL S o de st Te e O oO X O N A EEPROM PCI Connector M For greater detail a reference schematic for the OX16PCI954 evaluation board can be requested from Oxford Semiconductor Chapter 2 Evaluation Board Features gives further details about the features of the OX16PCI954 evaluation board UG 0011 J an 05 External Free Release 3 Evaluation Board Overview OX16PCI954 Evaluation Board User Guide This page is intentionally blank 4 External Free Release UG 0011 J an 05 OXFORD SEMICONDUCTOR Chapter 2 Evaluation Board Features The OX16PCI954 evaluation board contains a variety of sockets jumpers connectors and headers which enhance its flexibility J umpers Table 1 details the jumpers on the board and their use Table 1 J umpers on the OX16PC1954 Evaluation Board JP2 XTALsel Selects the oscillator type for the Crystal oscillator as supplied OX16PCI954 TTL oscillator JP4CLKsel Selects the oscillator type for the LB Clk out as supplied external UART TTL module RIO link Connects MIO 0 to RI of either External UART RIO PCI UART channel 0 or external UART channel
40. ugh the situation is complicated by the variety of null modem cables available For simple connections a three line cable connecting the signal ground receive and transmit lines is sufficient as shown in Figure 10 although some handshaking mechanism might still be necessary Figure 10 Null Modem Cable Without Handshaking Handshaking mechanisms in null modem cables can be defined in various ways such as loop back handshaking to each PC or complete handshaking between the two systems The most common cable types are shown in Figures 11 to 13 For a direct cable connection a null modem cable with loop back handshaking is usually acceptable as shown in Figure 11 on page 21 External Free Release UG 0011 J an 05 OX16PCI954 Evaluation Board User Guide RS422 amp RS232 Connector Pin Assignment Figure 11 Null Modem with Loop Back Handshaking RS232 Figure 14 shows an R5232 cable that can be used to monitor the serial s communication between two devices using a PC Two sockets are monitor cable connected straight through and the PC is connected to the third socket Figure 14 RS232 Monitor Cable 1N4148 UG 0011 J an 05 External Free Release 21 RS422 amp RS232 Connector Pin Assignment OX16PCI954 Evaluation Board User Guide 22 The monitor cable taps communication from both sides which means that the monitored information is garbage if the two devices happen to communicate simultaneously
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OXFORD SEMICONDUCTOR OX16PCI954 evaluation board user guide