ECAN527HR Isolated 1 Mb/s CAN interface board User's Manual
Contents
1. 527 14 RTD Embedded Technologies Inc 19 17 16 15 14 15 12 11 10 B 806 oo o o o Fig 2 Base address jumpers illustrating D8000h base address Interrupt Channel Factory setting IRQ 5 The header connector shown in Figure 3 lets you connect the onboard 82527 CAN controller interrupt output to one of the interrupt channels available on the host XT AT bus If your board has no AT bus extension interrupts 10 15 are not available DYI 151211107 6 5 4 3 2 Fig 3 Interrupt jumpers set to IRQ 5 Note The ECAN527HR hardware revision 1 4 onward do not support interrupt sharing ECAN527HR 15 RTD Embedded Technologies Inc ECAN527HR 16 RTD Embedded Technologies Inc Chapter2 BOARD INSTALLATION The ECAN527HR CAN bus interface board is very easy to connect to your industrial distributed control system Direct interface to PC 104 systems as well as EUROCARD boards is achieved This chapter tells you step by step how to install the ECAN527HR into your system After completing the installation use the diagnostic and test software to fully verify that your board is working The latest versions of the test software as well drivers are available on our website at lt www rtd com gt Board Installation Keep your board in its antistatic bag until you are ready to install it to your system When removing it from the bag hold the board at the edges and do not touch the components or connectors Please handle2. with the startup IMR saved and the interrupts temporarily disabled you can assign the interrupt vector to point to your ISR Again you can overwrite the appropriate entry in the vector table with a direct memory write but this is not recommended Instead use the DOS function 25h Set Interrupt Vector or if your compiler provides it the library routine for setting up interrupt vectors Remember that interrupt vector 8 corresponds to IRQO vector 9 for IRQI etc If you need to program the source of your interrupts do that next For example if you are using transmitted or received messages as an interrupt source program it to do that Finally clear the mask bit for your IRQ in the IMR This will enable your IRQ Common Interrupt mistakes 527 Remember hardware interrupts are from 8 15 XT IRQ s are numbered 0 7 Forgetting to clear the IRQ mask bit in the IMR e Forgetting to send the EOI command after ISR code Disables further interrupts 30 RTD Embedded Technologies Inc Example on Interrupt vector table setup in C code void far interrupt new IRQI handler void ISR function prototype define IRO1 VECTOR 3 Name for IRQ void interrupt far old IRQI1 dispatcher es ds di si bp sp bx dx cx ax ip cs flags Variable to store old IRQ Vector void far interrupt new IRQI handler void Function init irq handlers Inputs Nothing Returns Nothing Purpose Set the pointers in t
3. The first step in adding interrupts to your software is to write an interrupt service routine ISR This is the routine that will be executed automatically each time an interrupt request occurs for the specified IRQ An ISR is different from other subroutines or procedures First on entrance the processor registers must be pushed onto the stack before anything else Second just before exiting the routine you must clear the interrupt on the ECAN527HR by writing to the 82527 CAN controller and write the EOI command to the interrupt controller Finally when exiting the interrupt routine the processor registers must be popped from the system stack and you must execute the IRET assembly instruction This instruction pops the CS IP and processor flags from the system stack These were pushed onto the stack when entering the ISR Most compilers allow you to identify a function as an interrupt type and will automatically add these instructions to your ISR with one exception most compilers do not automatically add the EOI command to the function you must do it yourself Other than this and a few exceptions discussed below you can write your ISR as any code routine It can call other functions and procedures in your program and it can access global data If you are writing your first ISR we recommend you stick to the basics just something that enables you to verify you have entered the ISR and executed it successfully For example set a flag in y
4. to service a message received 23 RTD Embedded Technologies Inc Galvanic isolation of the CAN bus TAN_TKD CAN The galvanic isolation of the ECAN527HR is implemented using 1 Optocouplers for data transmission and 2 a DC DC converter to supply power to the CAN bus and the physical interface circuitry The high speed optocouplers are directly connected to the 82527 The optocouplers drive the CAN bus transceiver A special balanced CAN bus choke is used not only to improve immunity to bus noise but also to protect the bus transceiver This filter assists in conforming to the EN55022 Radiated Emission test requirements A 1W DC DC converter may be used to power other remote devices on the CAN bus The output power of this converter is isolated up to 1 5 kV peak Figure 7 illustrates the physical interface circuitry of the galvanically isolated CAN bus 5Y HERDLA Fig 7 CAN bus physical interface circuitry power supply omitted for clarity Fiberoptic interface ECAN527HR An optional fiber optic interface can be used to implement point to point communication using the CAN protocol Due to the physics of the fiberoptic media bitwise arbitration featured by the CAN protocol can not be supported The fiberoptic interface may be used in environments where either immunity to long distances or excessive noise is a design criteria It is possible to combine wire and fiberoptic connections in the same network using
5. 11898 compliant Fiberoptic CAN bus HP Versa Link connectors Non Isolated I O Header connector 10 Pin 527 32 RTD Embedded Technologies Inc Electrical Operating temperature range 40 to 85C Supply voltage 5V only Power consuption 115mA CE Meets CE approval for Heavy Industrial Equipment in RTD IDAN frame 527 33 RTD Embedded Technologies Inc Chapter 5 RETURN POLICY AND WARRANTY Return Policy If you wish to return a product to the factory for service please follow this procedure Read the Limited Warranty to familiarize yourself with our warranty policy Contact the factory for a Return Merchandise Authorization RMA number Please have the following available Complete board name e Board serial number A detailed description of the board s behavior List the name of a contact person familiar with technical details of the problem or situation along with their phone and fax numbers address and e mail address if available List your shipping address Indicate the shipping method you would like used to return the product to you We will not ship by next day service without your pre approval Carefully package the product using proper anti static packaging Write the RMA number in large 1 letters on the outside of the package Return the package to RTD Embedded Technologies Inc 103 Innovation Blvd State College PA 16803 0906 USA 527 34 RTD Embedded
6. Interrupt Service Routine ISR esses eene nennen reete etre enne tenente 28 Your ISR should have the following structure eese eee eene nennen trennen rene eene tenere 29 Saving the Startup Interrupt Mask Register IMR and interrupt vector eese 30 Common Interr pt MISTAKES oi a dec d ima ee eer tbe Pure oe eee eei hee Poe re E ee ee Pot 30 Example on Interrupt vector table setup in C code eese eene eene nennen trennen rennen 31 APPENDIX E DEO E O E O A OO E E O E E E A A E E O E E 32 ECAN527HR SPBCIFICATIONS a a DOOR 32 VERE LAA ATTE REEE E REE E 32 CAN Interface iie op eH ERROR PEN PRU P EE EEEE TEIR TESSI 32 using the RTD CAN Spider active hub on ECAN527HR 2 boards seen 32 Digital VO non 1s0lated aiio DP HER REC OD REEL REGERE EORR EGER ERPRURTR 32 COnDeCtOts De URP D EROR pnmo eis 32 BlectriCab Son eret br ee 33 CHAPTER 5 RETURN POLICY AND WARRANTY RETURN POLICY LIMITED WARRANTY LIST OF ILLUSTRATIONS AND TABLES FIGURES FIG 1 BOARD LAYOUT SHOWING JUMPER LOCATIONS ccccccccccccccccccccccccccccccecccccececececececececececeeeseceeseceseceseeeeeseseeeeees 12 FIG 2 BASE ADDRESS JUMPERS ILLUSTRATING D8000H BASE ADDRESS ccccccccecececesecesesecececesesesesssesseeseseeseseseeeeeaes 15 FIG 3 INTERRUPT JUMPERS SET TO IRQ 5 ccesssecesssssecssssccesessseceensnsecssneecesesseeceesscsecsensssesesneec
7. Technologies Inc Limited Warranty RTD Embedded Technologies Inc warrants the hardware and software products it manufactures and produces to be free from defects in materials and workmanship for one year following the date of shipment from RTD Embedded Technologies INC This warranty is limited to the original purchaser of product and is not transferable During the one year warranty period RTD Embedded Technologies will repair or replace at its option any defective products or parts at no additional charge provided that the product is returned shipping prepaid to RTD Embedded Technologies All replaced parts and products become the property of RTD Embedded Technologies Before returning any product for repair customers are required to contact the factory for an RMA number THIS LIMITED WARRANTY DOES NOT EXTEND TO ANY PRODUCTS WHICH HAVE BEEN DAMAGED AS A RESULT OF ACCIDENT MISUSE ABUSE such as use of incorrect input voltages improper or insufficient ventilation failure to follow the operating instructions that are provided by RTD Embedded Technologies acts of God or other contingencies beyond the control of RTD Embedded Technologies OR AS A RESULT OF SERVICE OR MODIFICATION BY ANYONE OTHER THAN RTD Embedded Technologies EXCEPT AS EXPRESSLY SET FORTH ABOVE NO OTHER WARRANTIES ARE EXPRESSED OR IMPLIED INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE AND RTD Embedd
8. active repeater nodes such as the RTD CAN Spider active 4 port CAN hub with multiple ECAN527HR boards The fiberoptic interface supports datarates up to 1 Mb s using Hewlett Packard Versa Link transmitter and receiver modules These modules enable direct connectivity to fiberoptic cables from your ECAN527HR The CAN Spider active hub also features compatible transmitters and receivers 24 RTD Embedded Technologies Inc Configuration EEPROM A configuration EEPROM may store up to 256 bytes of user data This memory may be used to store CAN bus parameters or other identifier codes required by the system The EEPROM used the I2C standard interfacing scheme The address of the EEPROM device is set to 000 To communicate to the EEPROM you must drive the clock and data lines of the device through the port P2 2 3 lines of the 82527 CAN controller The configuration EEPROM is interfaced through the digital I O lines of port P2 bits 2 and 3 LSB is 0 Data is read and written by clocking these lines to provide the serial interface required by the EEPROM device Digital I O Table 5 shows the functionality of the 82527 port P2 bits Bits 0 and 1 have two functionalities They may either drive the two onboard status LED s or operate as user TTL level I O The output impedance of this port is 100 Ohms This series resistor on every I O line provides protection against short circuits and transient voltages LEDI LED2 CLK DATA pi
9. interrupt handlers When an interrupt request line is driven high by a peripheral device such as the ECAN527 the interrupt controller checks to see if interrupts are enabled for that IRQ and then checks to see if other interrupts are active or requested and determines which interrupt has priority The interrupt controller then interrupts the processor The current code segment CS instruction pointer IP and flags are pushed onto the system stack and a new set of CS and IP are loaded from the lowest 1024 bytes of memory This table is referred to as the interrupt vector table and each entry to this table is called an interrupt vector Once the new CS and IP are loaded from the interrupt vector table the processor starts to execute code from the new Code Segment CS and from the new Instruction Pointer IP When the interrupt routine is completed the old CS and IP are popped from the system stack and the program execution continues from the point it was interrupted 527 27 RTD Embedded Technologies Inc Using Interrupt in your Program Adding interrupt support to your program is not as difficult as it may seem especially when programming under DOS The following discussion will cover programming under DOS Note that even the smallest mistake in your interrupt program may cause the computer to hang up and will only restart after a reboot This can be frustrating and time consuming Writing an Interrupt Service Routine ISR
10. to the items included in your ECAN527HR delivery several software and hardware accessories are available Call your distributor for more information on these accessories and for help in choosing the best items to support your distributed control system Application software Third party high level protocol drivers QNX drivers CanOpen libraries for QNX and LINUX Hardware accessories CANSPIDER Active hub for fiberoptical networking using ECAN527 2 IDAN ruggedized aliminium frames and enclosures for PC 104 systems IDAN ECAN527HR Using this manual This manual is intended to help you install your new ECAN527HR card and get it running quickly while also providing enough detail about the board and it s functions so that you can enjoy maximum use of it s features even in the most demanding applications When you need help This manual and all the example programs will provide you with enough information to fully utilize all the features on this board If you have any problems installing or using this board contact our Technical Support Department 814 234 8087 during European business hours or send a FAX to 814 234 5218 or Email to sales rtd com When sending a FAX or Email request please include your company s name and address your name your telephone number and a brief description of the problem BOARD SETTINGS The ECAN527HR CAN bus interface board has jumper settings which can be changed to suit your application and hos
11. 7 9 RTD Embedded Technologies Inc 2 The fiberoptic physical interface is implemented using HP Versa Link fiberoptic transmitter and receiver The fiberptic interface may be used for point to point CAN networks Due to the fiberoptic technology bitwise arbitration of the CAN bus protocol can not be supported You should use the CANSPIDER active hub available from RTD to build fiberoptic CAN systems Mechanical description The ECAN527HR is designed on a PC 104 form factor An easy mechanical interface to both PC 104 and EUROCARD systems can be achieved Stack your ECAN527HR directly on a PC 104 compatible computer using the onboard mounting holes Connector description There is a 10 pin interface connector on the ECAN527HR which directly interfaces to the galvanivally isolated CAN bus The fiberoptic interface may directly connect to fiberoptic cable using HP Versa Link PCB mounted connectors The general purpose digital outputs and inputs are connected to the ECAN527HR by 10 pin header connector What comes with your board You will receive the following items in your ECAN527HR package ECANS27HR CAN bus interface module User s manual Note Software and drivers are available on our website at www rtd com If any item is missing or damaged please call RTD Embedded Technologies Inc customer service department at 814 359 3174 527 10 RTD Embedded Technologies Inc Board accessories In addition
12. ECAN527HR Isolated 1 Mb s CAN interface board User s Manual RTD Embedded Technologies Inc Real Time Devices Accessing the Analog World BDM 610020019 Rev A ECANS527HR ISOLATED 1 MB S CAN INTERFACE BOARD USER S MANUAL RTD Embedded Technologies INC 103 Innovation Blvd State College PA 16803 0906 Phone 1 814 234 8087 FAX 1 814 234 5218 E mail sales rtd com techsupport rtd com web site http www rtd com Revision History Rev A New Manual Naming Method Published by RTD Embedded Technologies Inc 103 Innovation Blvd State College PA 16803 0906 Copyright 1999 2002 2003 by RTD Embedded Technologies Inc All rights reserved Printed in U S A The RTD Logo is a registered trademark of RTD Embedded Technologies cpuModule and utilityModule are trademarks of RTD Embedded Technologies PhoenixPICO and PheonixPICO BIOS are trademarks of Phoenix Technologies Ltd PS 2 PC XT PC AT and IBM are trademarks of International Business Machines Inc MS DOS Windows Windows 95 Windows 98 and Windows NT are trademarks of Microsoft Corp PC 104 is a registered trademark of PC 104 Consortium All other trademarks appearing in this document are the property of their respective owners TABLE OF CONTENTS CHAPTER 1 INTRODUCTION 9 FEATURES THE ECAN527HR 9 CAN BUS CONTRO TER 2 1 eterne ettet t te
13. PTION 22 Galvanic isolation of the CAN bus esses eere nennen nennen trente enne et rene nette tne tne 24 Fiberoptic interface i Lea Y ett loves E pee eet tl Ue dete e te boe Te RS eb erre Ede cup e 24 Configuration EEPROM a ttd ee Ete ee ree YE Rte ERE Ee EDS Le REEL voor eoa 25 Digital 1 0 3 eed eo Ee e Oe ia dr EEUU Ie 25 CHAPTER 4 BOARD OPERATION AND PROGRAMMING sssssssssssssssssssssssssssssssssssssssssssssssssssssssee 26 DEFINING THE MEMORY sie sero ox TP RE ERE Fr QUEUE Te RELIER EUREN KR ERO SE EREE ERIS 26 Bit timing Yeglsterss nasse aue t e D Itu ater dbi tied ee edd tien 26 INTERRUPTS S S eene ELM EA oe Ere dier 26 What is an interr pt 225 PAAR e P e ete T Ce e E ee eS e eere 26 Interrupt request lines iae eee 27 8259 Programmable Interrupt 27 Interrupt Mask Register IMR c cccssccesssesesecescecesecesscecesecessceceaceesacecsaceesaeecsaeeesaeecsuceeeaeceeeecsaceceaceseaeeceeeeeeaaees 27 End of Interrupt EOI Command eese eene teens 27 What exactly happens when an interrupt occurs eese eene enne tenen nennen eren eene enne treten 27 Using Interr pt in your Programy piere EA EU Eten Ce eoa e EIE Deae RR re ehe Poe o ERI ee EYE Da Eo Ee veta 28 Writing an
14. ataModule stack 3U rack or enclosure installation with a EUROCARD CPU containing one ECANS27 The PC 104 system can easily be inserted into a 19 rack installation using the CPU as a form factor adapter Assemble your PC 104 data modules on a RTD single board computer and install the system in an 19 enclosure Multiple ECAN527HR boards can easily be connected to this system See figure 5 below Fig 5 19 Eurocard rack installation with an integrated PC 104 dataModule and EUROCARD cpuModule computer system ECAN527HR 18 RTD Embedded Technologies Inc External I O connections General purpose digital I O Table 2 1 shows the connector layout of the ECAN527HR digital I O connector J28 This connector is located toward the left side of the board Refer to this diagram when making signal connections Pin Number Function 1 1 LEDI 2 LED2 EEPROM clk EPROM data I O 3 I O 4 I O 5 I O 6 5V Table 3Digital I O connector of the ECAN527HR Note T O signals 3 and 4 are reserved for the use of the non volatile EEPROM In this case these pins are not available for user I O 527 19 RTD Embedded Technologies Inc Galvanically isolated bus connector Table 4 shows the CAN physical interface connector This connectors is used to route the CAN bus through your ECAN527HR board It is located at the top of your board This connector conforms to the ISO11898 specification Table 4 Physical
15. can be configured to either transmit of to receive except for the last message object The last message object is a receive only buffer with a special mask design to allow selected groups of different message identifiers to be received Each message identifier contains control and status bits A message object with a direction set for receive will send a remote frame by requesting a message transmission A message set as transmit will be configured to automatically send a data frame whenever a remote frame with a matching identifier is received over the CAN bus All message objects have separate transmit and receive interrupts and status bits allowing the CPU full flexibility in detecting when a remote frame has been sent or received The 82527 chip supports a global masking feature for acceptance filtering This feature allows the user to globally mask or don t care any identifier bits of the incoming message This mask is programmable to allow the user to design an application specific message identification strategy There are separate global mask for standard and extended frames The incoming message first passes through the global mask and is matched to the identifiers in the message objects 1 14 If there is no identifier match then the message passes through the local mask in message object 15 The local mask allows a large number of infrequent messages to be received by the 82527 Message object 15 is also buffered to allow the CPU time
16. ed Technologies EXPRESSLY DISCLAIMS ALL WARRANTIES NOT STATED HEREIN ALL IMPLIED WARRANTIES INCLUDING IMPLIED WARRANTIES FOR MECHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE LIMITED TO THE DURATION OF THIS WARRANTY IN THE EVENT THE PRODUCT IS NOT FREE FROM DEFECTS AS WARRANTED ABOVE THE PURCHASER S SOLE REMEDY SHALL BE REPAIR OR REPLACEMENT AS PROVIDED ABOVE UNDER NO CIRCUMSTANCES WILL RTD Embedded Technologies BE LIABLE TO THE PURCHASER OR ANY USER FOR ANY DAMAGES INCLUDING ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES EXPENSES LOST PROFITS LOST SAVINGS OR OTHER DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PRODUCT SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF INCIDENTAL OR CONSEQUENTIAL DAMAGES FOR CONSUMER PRODUCTS AND SOME STATES DO NOT ALLOW LIMITATIONS ON HOW LONG AN IMPLIED WARRANTY LASTS SO THE ABOVE LIMITATIONS OR EXCLUSIONS MAY NOT APPLY TO YOU THIS WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS AND YOU MAY ALSO HAVE OTHER RIGHTS WHICH VARY FROM STATE TO STATE ECAN527HR 35 RTD Embedded Technologies Inc ECAN527HR RTD Embedded Technologies Inc 103 Innovation Blvd State College PA 16803 0906 USA Our website www rtd com 36 RTD Embedded Technologies Inc NOTES Base Address IRQ selection 527 37 RTD Embedded Technologies Inc
17. ed physical interface with CAN transceiver Optional fiberoptic transmitter and receiver for noisy environments 6 user accessible bit programmable bidirectional digital I O 2 status LED s 5V only operation PC 104 compliant The following paragraphs briefly describe the major features of the ECAN527HR more detailed discussion is included in Chapter 3 Hardware description and in Chapter 4 Board operation and programming The board set up is described in Chapter 1 Board Settings A full description of the Intel 82527 CAN controller is included in Chapter 4 CAN bus controller The ECAN527HR CAN bus interface is implemented using the Intel 82527 chip This controller supports CAN Specification 2 0 This versatile chip supports standard and extended data and remote frames as follows A programmable global message identifier mask 15 message objects of 8 byte data length and a programmable bit rate This fully integrated chip supports all the functionality of the CAN bus protocol Physical Interface Industrial environments require galvanic isolation and bus filtering to provide reliable data communication and safety The ECANS27HR has two options for the physical interface 1 The galvanivally isolated physical interface is implemented using high speed optocouplers and a DC DC converter To protect the input from radiated bus noise a special balanced bus filter is used This filter is designed to meet EMI requirements 52
18. esnsnsecsenessessenesessnsnsesses 15 4 ECAN527HR INTEGRATED IN A PC 104 DATAMODULE STACK cccccccccecececesesececeseceseseseseseseseessssesesseseseeeanees 18 Fic 5 19 EUROCARD RACK INSTALLATION WITH AN INTEGRATED 104 DATAMODULE AND EUROCARD CPUMODUEE COMPUTER SYSTEM see et educa capes sob cae 18 FIG 6 ECANS527HR BLOCK DIAGRAM Innes Head e OEE 22 7 CAN BUS PHYSICAL INTERFACE CIRCUITRY POWER SUPPLY OMITTED FOR CLARITY eene 24 TABLES TABLE 1 FACTORY CONFIGURED JUMPER SETTINGS SEE FIGURE 1 1 FOR DETAILED 12 TABLE 2 BASE ADDRESS JUMPER SETTINGS ccccccccccccecccesccecccecesesecesesesesesesesesesesesesecesesesesssesssesesesesesasasauauauauauananananaea 14 TABLE 3DIGITAL I O CONNECTOR OF THE ECANS27HR eeeee eee emen nnnnnnnnnnnses ese e esses e ess s sss esee ee 19 TABLE 4 PHYSICAL INTERFACE CONNECTOR PINOUTS OF THE ECANS27HR eee eene 20 TABLE 5DIGITAL I O CONFIGURATION OF PORT P2 OF THE 82527 CHIP cccccccccccccccccccececesecesececesesesesesessssseseseseuseeseeess 25 Chapter 1 INTRODUCTION This user s manual describes the operation of the ECAN527HR CAN bus interface board Features of the ECAN527HR include 1 Mb s maximum datarate fully programmable Full CAN functionality 2 0 B Intel 82527 CAN bus controller 256 bytes of configuration EEPROM Galvanically isolat
19. he interrupt table to point to our funtions ie setup for ISR s void init handlers void disable old IRQ1 handler dos getvect IRQ1 VECTOR 8 dos setvect IRQ1 VECTOR 8 new IRQI handler Gi old mask z inp 0x21 outp 0x21 Gi old mask amp 1 lt lt IRQ1_VECTOR _enable Function restore do this before exiting program Inputs Nothing Returns Nothing Purpose Restore interrupt vector table void restore void Restore the old vectors disable dos setvect IRQ1 VECTOR 8 old IRQI1 handler outp 0x21 Gi old mask _enable ECAN527HR 31 RTD Embedded Technologies Inc APPENDIX ECAN527HR Specifications Host Interface Memory mapped into low memory occupies 256 bytes Jumper selectable base address 11 jumpers 8 bit data bus 16 bit PC 104 bus connector Jumper selectable XT and AT interrupts CAN Interface Galvanically isolated transceiver with 1 Mb s datarate Timing parameters and speed of bus programmable Balanced CAN bus choke for low EMI emissions Jumper selectable 120 Ohm onboard termination resistor 0 8W 5V isolated output power for other field devices Fiberoptic transmitter and receiver 1Mb s datarate using the RTD CAN Spider active hub on ECAN527HR 2 boards Digital I O non isolated Number of lines 6 LED s 2 Series resistor 100 Ohms Pull up Pull down Bits 1 3 10K pull down Connectors Galvanically isolated CAN bus ISO
20. interface connector pinouts of the ECAN527HR 527 20 RTD Embedded Technologies Inc ECAN527HR 21 RTD Embedded Technologies Inc Chapter 3 HARDWARE DESCRIPTION Chapter 3 Hardware Description describes the major features of the ECAN527HR the Intel 82527 CAN bus controller Galvanic isolation of the CAN bus the Fiberoptic interface the Onboard configuration EEPROM and Digital I O Figure 6 shows the general block diagram of the ECAN527HR This chapter describes the major features of the ECAN527HR the Intel 82527 CAN bus controller Galvanic isolation of the CAN bus the Fiberoptic interface the Onboard configuration EEPROM and Digital I O 4 BUS RESISTORS Fig 6 ECAN527HR Block diagram ECAN527HR 22 RTD Embedded Technologies Inc 82527 bus controller Reference note 527 Intel publication CAN Architectural Overview Automotive Products Databook The 82527 CAN controller consists of six functional blocks The CPU interface logic manages the communication to the host computer The CAN controller interfaces to the CAN bus and implements the protocol rules of the CAN protocol for the transmission and reception of messages The RAM is the physical interface layer between the host CPU and the CAN bus One eight bit I O port provides low speed I O capabilities The 82527 RAM provides storage for 15 message objects of 8 byte length Each message object has a unique identifier and
21. may occur and data read from the board may be corrupted To avoid this problem make sure you set up the base address first using the 11 jumpers marked ADDR which let you choose from number of addresses in your host computers memory map Should the factory installed setting of D0000h be unusable for your system configuration you may change this setting to another using the options illustrated in Table 2 The table shows the jumper settings and their corresponding values in hexadecimal values Make sure you verify the correct location of the base address jumpers When the jumper is removed it corresponds to a logical 0 connecting the jumper to a 1 When you set the base address of the module record the setting in the table inside the back cover of this manual after the Appendices Note If you are using a memory manager such as QEMM make sure you exclude the 527 memory section you are occupying by ECAN527 for example X D0000 DOOFF 13 RTD Embedded Technologies Inc Address Jumper Settings ECANS27HR Jumper Settings Base Address Hex 18 17 16 15 0 JUMPER 1 JUMPER installed Note A19 is always decoded as 1 Table 2 Base address jumper settings Note The above table illustrates only the settings for the high address bits A18 A15 If you for instance want to configure address 0 00 DOEFF for your ECAN527HR you must set the jumpers as 1201 0000 1110 Address line A19 is always decoded as 1
22. nal routine at the point where its execution was interrupted Interrupts are a very flexible way of dealing with asynchronous events Keyboard activity is a good example your computer cannot predict when you might press a key and it would be a waste of processor time to do nothing while waiting for a keystroke to occur Thus the interrupt scheme is used and the processor proceeds with other tasks When a keystroke occurs the keyboard interrupts the processor the processor then gets the keyboard data which is then placed into the memory It then returns to what it was doing before the interrupt occurred Other common devices that use interrupts are network boards A D boards serial ports etc Your ECAN527HR can interrupt the main processor when a message is received or transmitted if interrupts are enabled on the ECANS27HR board By using interrupts you can write powerful code to interface to your CAN network 527 26 RTD Embedded Technologies Inc Interrupt request lines To allow different peripheral devices to generate interrupts on the same computer the PC AT bus has interrupt request channels IRQ s A rising edge transition on one of these lines will be latched into the interrupt controller The interrupt controller checks to see if the interrupts are to be acknowledged from that IRQ and if another interrupt is being processed it decides if the new request should supercede the one in progress or if it has to wait until the
23. one in progress is done The priority level of the interrupt is determined by the number of the IRQ IRQO has the highest priority IRQ15 the lowest Many of the IRQ s are used by the standard system resources IRQO is dedicated for the internal timer 1 is dedicated to the keyboard input IRQ3 for serial port COM2 and IRQ4 for serial port COMI Often interrupts 3 5 and 7 are free for the user 8259 Programmable Interrupt Controller The chip responsible for handling interrupt requests in a PC is the 8259 Interrupt Controller To use interrupts you will need to know how to read and set the 8259 s internal interrupt mask register IMR and how to send the end of interrupt EOI command to acknowledge the 8259 interrupt controller Interrupt Mask Register IMR Each bit in the interrupt mask register IMR contains the mask status of the interrupt line If a bit is set equal to 1 then the corresponding IRQ is masked and it will not generate an interrupt If a bit is cleared equal to 0 then the corresponding IRQ is not masked and it can then generate an interrupt The interrupt mask register is programmed through port 21h End of Interrupt EOI Command After an interrupt service routine is complete the 8259 Interrupt Controller must be acknowledged by writing the value 20h to port 20h What exactly happens when an interrupt occurs Understanding the sequence of events when an interrupt is triggered is necessary to correctly write
24. os proe Table 5Digital I O configuration of port P2 of the 82527 chip 527 25 RTD Embedded Technologies Inc Chapter 4 BOARD OPERATION AND PROGRAMMING This chapter shows you how to program and use your ECAN527HR It provides a complete detailed description of the memory map and a detailed discussion of programming operations to aid you in programming The full functionality of the ECANS27HR is described in the datasheet reprint from Intel on the 82527 CAN controller chip Defining the Memory Map The memory map of the ECAN527HR occupies 256 bytes of host PC low memory space This window is freely selectable by the user as described in Chapter 1 table 2 After setting the base address you have access to the internal resources of the 82527 CAN controller chip as is described in the next sections reprinted from the Intel 82527 manual Bit timing registers These are the recommended bit timing register values for reliable communication at 1MBps for 500Kbps change to 01h BIT TIMO 00h BIT TIMI C6h For more information on these and other control registers of the CAN controller chip please refer to the component specific datasheet reprinted from Intel attached Interrupts What is an interrupt An interrupt is an event that causes the processor in your computer to temporarily halt its current process and execute another routine Upon completion of the new routine control is returned to the origi
25. our ISR and in your main program check for the flag Note If you choose to write your ISR in in line Assembly you must push and pop registers correctly 527 and exit the routine with the IRET instruction instead of the RET instruction There are a few precautions you must consider when writing ISR s The most important is do not use any DOS functions or functions that call DOS functions from an interrupt routine DOS is not reentrant that is a DOS function cannot call itself In typical programming this will not happen because of the way DOS is written But what about using interrupts Then you could have the situation such as this in your program If DOS function X is being executed when an interrupt occurs and the interrupt routine makes a call to the DOS function X then function X is essentially being called while active Such cases will cause the computer to crash DOS does not support such operation A general rule is that do not call any functions that use the screen read keyboard input and any file I O routines should not be used in ISR s The same problem of reentrancy exists for many floating point emulators as well meaning you should avoid floating point mathematical operations in your ISR Note that the problem of reentrancy exists no matter what programming language you use Even if you are writing your ISR in Assembly language DOS and many floating point emulators are not reentrant Of course there are wa
26. p 0x20 0x20 Acknowledge the interrupt controller 29 RTD Embedded Technologies Inc Saving the Startup Interrupt Mask Register IMR and interrupt vector The next step after writing the ISR is to save the startup state of the interrupt mask register IMR and the original interrupt vector you are using The IMR is located in address 21h The interrupt vector you will be using is located in the interrupt vector table which is an array of 4 byte pointers addresses and it is locate din the first 1024 bytes of the memory Segment 0 offset 0 You can read this value directly but it is a better practice to use DOS function 35h get interrupt vector to do this Most C compilers have a special function available for doing this The vectors for the hardware interrupts on the XT bus are vectors 8 15 where IRQO uses vector 8 and IRQ7 uses vector 15 Thus if your ECAN527HR is using IRQS it corresponds to vector number 13 Before you install your ISR temporarily mask out the IRQ you will be using This prevents the IRQ from requesting an interrupt while you are installing and initializing your ISR To mask the IRQ read the current IMR at I O port 21h and set the bit that corresponds to tout IRQ The IMR is arranged so that bit 0 is for IRQO and bit 7 is for IRQ7 See the paragraph entitled Interrupt Mask Register IMR earlier in this discussion for help in determining your IRQ s bit After setting the bit write the new value to I O port 21h
27. t computer memory configuration The factory settings are listed and shown in the diagram in the beginning of this chapter 527 11 RTD Embedded Technologies Inc Factory configured Jumper Settings Table 1 illustrates the factory jumper setting for the ECAN527HR Figure 1 shows the board layout of the ECAN527HR and the locations of the jumpers The following paragraphs explain how to change the factory jumper settings to suit your specific application Table 1Factory configured jumper settings See figure 1 1 for detailed locations JUMPER NUMBER OF Jumper Name NUMBERS FACTORY DEFAULT ADDR BASE ADDRESS 11 D0000 IRQ HOST INTERRUPT 10 5 CAN BUS 134 TERMINATION 1 CLOSED t ECAN527HR EXIST LET NU CE ECANS27 E ET DTEITTETTI E TT BA 1 AM 1 331 Fig 1 Board layout showing jumper locations RTD Embedded Technologies Inc Base Address Jumpers Factory setting 00000 h The ECAN527HR is memory mapped into the low memory of your host XT AT The ECANS527HR board occupies a memory window of 256 bytes starting from the base address The most common cause of failure when you are first setting up your module is address contention Some of your computers memory space is already occupied by other devices and memory resident programs When the ECAN527HR attempts to use reserved memory addresses already used by another device erratic performance
28. the board in an antistatic environment and use a grounded workbench for testing and handling of your hardware Before installing the board in your computer check the jumper settings Chapter 1 reviews the factory settings and how to change them If you need to change any settings refer to the appropriate instructions in Chapter 1 Note that incompatible jumper settings can result in unpredictable board operation and erratic response General installation guidelines 1 Turn OFF the power to your computer and all devices connected to ECAN527 2 Touch the grounded metal housing of your computer to discharge any antistatic buildup and then remove the board from its antistatic bag 3 Hold the board by the edges and install it in an enclosure or place it on the table on an antistatic surface 4 Connect the board to the CAN fieldbus using the two fieldbus interface header connectors Make sure the polarity of the cable is correct Both connectors are identical one of these headers may be used to bring the CAN bus to the board the other connector interfaces your ECAN527HR to the CAN bus Installation integrated with a PC 104 module stack Secure the four PC 104 installation holes with standoffs Connect the board to the CAN bus using the two fieldbus interface header connectors alternatively use the fiberoptic connectors 527 17 RTD Embedded Technologies Inc RIP dataModule Fig 4 ECANS27HR integrated in a PC 104 d
29. tte neo Re PURSE EET OE TEE EE EEES EA SE eE AEAEE 9 Iso Ud luci e 9 MECHANICAL DESCRIPTION csi 3 etin evene ettet tte eme bu Ro nrernebegveperte E EEEE TAE EE EERENS AEE SEEE SEO TEER SEEE 10 CONNECTOR DESCRIPTION NEEE E EEE EE ESEA EE EE EE TERES 10 WHAT COMES WITH YOUR BOARD sseeeeeeeeee eee en 10 BOARD ACCESSORIES corti dete eet PER PREMIERE EUER REOR ETRAS AA E NONE e PIS s TESE EE 11 USING THIS MANUAL e eR eer e ete EET e bebe tarte eMe riter ote REN 11 WHEN YOU NEED HELP nibii ntes teen eene ee Pieve eor Ee Pres 11 BOARD SETTINGS efe epe duci e dte nce tee Pep tede dete e tes 11 BASE ADDRESS JUMPERS FACTORY SETTING 00000 13 CHAPTER 2 BOARD INSTALLATION 17 BOARD INSTALLATION 2 24pm th t RO eiecit ci eii 17 General installation guidelines eed re e t e ee e ege virer b eee A eae Pues 17 Installation integrated with a PC 104 module stack eese nennen eene ene 17 External I O c nnections eie d e Habe Brie EC REX ER Nee eA E Soothes 19 General purpose digital I Q aee te ete tke ec ete oe Dee obere eoi ee 19 Galvanically isolated CAN bus tree tenete 20 CHAPTERS HARDWARE DESCRI
30. ys to avoid this problem such as those which involve checking if any DOS functions are currently active when your ISR is called but such solutions are beyond the scope of this manual 28 RTD Embedded Technologies Inc The second major concern when writing ISR s is to make them as short as possible in term of execution time Spending long times in interrupt service routines may mean that other important interrupts are not serviced Also if you spend too long in your ISR it may be called again before you have exited This will lead to your computer hanging up and will require a reboot Your ISR should have the following structure Push any processor registers used in your ISR Most C compiler do this automatically 527 Put body of your routine here Read interrupt status register of the 82527 chip on your ECAN527HR board Clear the interrupt bit by writing to the 82527 CAN controller Issue the EOI command to the 8259 by writing 20h to address 20h Pop all registers Most C compilers do this automatically The following C example shows what the shell of your ISR should be like Function new_IRQ_handler Inputs Nothing Returns Nothing Sets the interrupt flag for the EVENT void interrupt far new IRQ handler void IRQ flag 1 Indicate to main process interrupt has occurred Your program code should be here Read interrupt status registers Clear interrupt on ECAN527 out
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