ECAN1000HR Isolated CAN interface board User's Manual
Contents
1. REPE 29 CAN INTEREAGES Scene osa otio eine aer eed cdi electi rd cce Re 29 CONNECTORS pon eh when Teide 29 BEECTRICAL uetus esatta etes utu estu 29 o 9 29 ECANI1000HR CAN Bus Interface 6 RTD Embedded Technologies Inc CHAPTER 7 RETURN POLICY AND WARRANTY cccccccscsscsscscscsscesseccescuccecsescessuscuscuscuscuscuscuscnscusees 30 RETURN POEICY 5 eterne eem etes Mem er 30 LIMITED WARRANTY eene EE tieni 31 ILLUSTRATIONS FIGURE 1 COMPONENT LOCATIONS 12 FIGURE 2 BASE ADDRESS JUMPERS ILLUTRATING ADDRESS 300 2 222 2 2 2 2 14 FIGURE 3 5 05 0 14 FIGURE 4 ECAN1000HR INTEGRATED IN A 104 RTD CPUMODULE STACK ee 16 FIGURE 5 19 EUROCARD RACK INSTALLATION WITH AN INTEGRATED PC 104 DATAMODULE AND 16 FIGURE 6 ECANI000HR BLOCK DIAGRAM 18 TABLES TABLE 1 FACTORY CONFIGURED JUMPER SETTINGS 0 c0ccccccssccccesscececssececeessececssecececsseeeceesseesesseeeeeenaeeeenssseeeens 11 TABLE 2 JP1 BASE ADDRESS JUMPER SETTINGS 13 TABLE2. 9 BOARD ACCESSORIES 5 unite nene apnea toit nei 10 USING THIS MANUAL deste pre ee it iei prem pec pte ee De pev E 10 WHEN YOU NEED HELP cnc ot aue eiae ea Maec 10 CHAPTER 2 BOARD SETTINGS 5555 n 11 FACTOR Y CONFIGURED JUMPER SETTINGS niieoee e eee EEr o a EE E E Ea eE E EEEE E S 11 BASE ADDRESS JUMPERS FACTORY SETTING 300 1 2220220 50000000000000000000000000000000500000 12 INTERRUPT CHANNEL FACTORY SETTING IRQS cc ccccsssscessssceceesececsencececsencecsesaececseaaececaeeeesesaeeecnesaeeeeseeeeeeses 14 CHAPTER 3 BOXRDINSEAEDATION c ppc t e tbe cele EET scien 15 BOARD INSTALLATION eh ek iden ete ek ea ieee 15 General installationxuidelinass ettet er P be Pee Ns ere ee 15 Installation integrated with a PC 104 module stack eee 15 30 rack or enclosure installation with a EUROCARD CPU containing an 16 J12 GALVANICALLY ISOLATED CAN BUS 2 22 2 021224 60000000 00000000000000000000000000000000 17 134 GALVANICALLY ISOLATED CAN BUS TERMINATION JUMPER eese enne 17 CHAPTER 4 HARDWARE DESCRIPTION sssssssssssssssssssccssssescsssseccsssnscccsssnecssssnsscesssnscces
3. define IRQ1_VECTOR 3 Name for IRQ void interrupt far old IRQ1 dispatcher es ds di si bp sp bx dx cx ax ip cs flags Variable to store old IRQ Vector void far interrupt new IRQ1 hanaler void Function init handlers Inputs Nothing Returns Nothing Purpose Set the pointers in the interrupt table to point to our funtions ie setup for ISR s void init_irq_handlers void disable old IRQ1 handler dos getvect IRQ1 VECTOR 8 dos setvect IRQ1 VECTOR 8 new IRQ1 handler Gi old mask 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 IRQ1 handler outp 0x21 Gi old mask _enable CAN Bus Interface 28 RTD Embedded Technologies Inc Chapter 6 ECAN1000HR SPECIFICATIONS Host Interface mapped device occupies 3 bytes Jumper selectable base address 8 bit data bus 16 bit AT bus connector Jumper selectable XT and AT interrupts CAN Interfaces Galvanically isolated transceiver 1 Mb s datarate Timing parameters and speed of bus programmable Balanced CAN bus Choke Jumper selectable 120 Ohm termination resistors Transceiver type Philips 826251 0 8W 5V isolated output power for oth
4. 3 J12 CAN BUD CONNECTOR 0 c cccccsescecesssccecessseeeceecececsseeecssssececeseeceeseseceesseecensssecesenseeeceenseeeensaaees 17 TABLE 4 PHYSICAL INTERFACE CONNECTOR J12 PINOUT OF THE 1000 17 TABLE4 ECAN MEMORY aD ne 21 ECANI1000HR CAN Bus Interface 7 RTD Embedded Technologies Inc Chapter 1 INTRODUCTION This user s manual describes the operation of the ECAN1000HR CAN bus Interface board Features Some of the key features of the ECAN1000HR include SJA1000 CAN network controller Electrically compatible with the 82 200 stand alone CAN controller chip 1 Mb s maximum datarate fully programmable Full CAN functionality 2 0 B Extended receive buffer 64 byte FIFO 16 MHz clock frequency Galvanically isolated physical interfaces mapped host interface using three addresses 40 to 85C operational temperature 5V only operation PC 104 compliant The following paragraphs briefly describe the major features of the ECAN1000HR A more detailed discussion in included in Chapter 4 Hardware description and in Chapter 5 Board operation and programming The board setup is described in Chapter 2 Board Settings A full description of the Philos SJA1000 CAN controller is included in Chapter 5 Board operation and programming CAN bus controller The ECAN1000HR CAN bus interface is implemented using the Philips SJA1000 cont
5. 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 ECAN1000HR outp 0x20 0x20 Acknowledge the interrupt controller Saving the Startup Interrupt Mask Register IMR and interrupt vector The next step after writing the ISR is to save the start up state of the interrupt mask register 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 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 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 ECAN1000HR is using IRQ5 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 the IRQ T
6. if the new request should supersede the one in progress or if it has to wait until the one in progress has been completed The priority level of the interrupt is determined by the number of the IRQ as follows IRQO has the highest priority whilst IRQ15 has the lowest Many of the IRQ s are used by the standard system resources IRQO is dedicated to the internal timer IRQ1 is dedicated to the keyboard input IRQ3 for the serial port COM2 and IRQA for the serial port COM1 Often interrupts 2 5 and 7 are free for the user ECANI1000HR CAN Bus Interface 22 RTD Embedded Technologies Inc 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 ackn
7. module stack e Secure the four PC 104 installation holes with standoffs Connect the board to the CAN bus using the CAN header connector J12 ECANI1000HR CAN Bus Interface 15 RTD Embedded Technologies Inc RTD dataModule Figure 4 ECAN1000HR integrated in PC 104 RTD cpuModule stack 3U rack or enclosure installation with a EUROCARD CPU containing an ECAN1000HR The PC 104 system can be easily inserted into a 19 rack installation using the CPU as a form factor adaptor Assemble your PC 104 data modules on an RTD single board EUROCARD computer and install the system in a 19 enclosure Multiple ECAN1000HR boards can be easily connected to this system See figure 5 below PE RTD dataModule EUROCARD AT 96 CPU WITH 4 EXPANSION BUS Figure 5 19 Eurocard rack installation with an integrated PC 104 dataModule and EUROCARD cpuModule computer system ECANI1000HR CAN Bus Interface 16 RTD Embedded Technologies Inc J12 Galvanically isolated CAN bus connector Table 3 below shows the CAN physical interface connector pinout This connector is to the right hand side of your board marked J12 The pinout conforms to the ISO 11898 2 standard specification N C GND isolated BUS L BUS H GND isolated N C N C 5V isolated GND isolated Table 3 J12 CAN Bud Connector 9 7 5 3 1 10 8 6 4 2 Table 4 Physical interface connector J12 pinout
8. D FITNESS FOR A PARTICULAR PURPOSE AND RTD Embedded 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 CAN Bus Interface 31 RTD Embedded Technologies Inc ECANI000HR CAN Bus Interface RTD Embedded Technologies Inc 103 Innovation Blvd State College PA 16803 0906 USA Our website www rtd com 32 RTD Embedded Technologies Inc
9. ECAN1000HR Isolated CAN interface board User s Manual 777 Real Time Devices RTD Embedded Technologies Inc Accessing the Analog World BDM 610020026 Rev A 1000 CAN Bus Interface 2 RTD Embedded Technologies Inc ECANI000HR ISOLATED 1 MB S CAN INTERFACE BOARD USER S MANUAL Declaration of Conformity of the ECAN1000HR to the following Directives EU EMC directive 89 336 EEC EU Low Voltage directive 73 23 EEC using the relevant section of the following EU standards and other normative documents EN50081 2 1995 EN55022 information EN50082 2 1995 EN61000 4 3 EN61000 4 6 EN61000 4 2 EN61000 4 4 Emissions generic requirements Measurement of radio interference characteristics of technology equipment Immunity generic requirements Radio frequency electromagnetic field AM modulated Radio frequency common mode AM modulated Electrostatic discharge Fast transients Relevant documents are available upon request from RTD Tomi Hanninen Managing Director RTD Finland Oy 1000 CAN Bus Interface 3 RTD Embedded Technologies Inc 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 ECANI000HR CAN Bus Interface 4 RTD Embedded Technologies Inc Revision History 28 11 1991 Release 1 0 15 07 2001 Name
10. PER SETTINGS ECAN1000HR Base address Hex Jumper Setings 8 A7 6 5 0 JUMPER OFF 1 JUMPER CLOSED Table 2 JP1 Base Address Jumper Settings 200 220 240 260 280 2A0 2 0 2 0 320 340 360 380 0 3C0 3E0 Note The above table illustrates the settings for the high address bits A8 A5 AQ is always decoded 1 ECANI1000HR CAN Bus Interface 13 RTD Embedded Technologies Inc BASE 1 Blololelololole Figure 2 Base address jumpers illutrating address 300 h Interrupt channel Factory setting IRQ5 The header connector shown in Figure 3 below lets you connect the onboard SJA1000 CAN controllers interrupt outputs to one of the interrupt channels available on the host XT AT bus If your board has no AT extension interrupts IRQ 10 15 are not available IRQ SELECTION alaloiala 15 12110 7 8 5 43 2 Figure 3 Interrupt set to IRQ 5 Note The ECAN1000HR does not support interrupt sharing This feature is sometimes regarded as a part of the PC 104 special features After extensive software and hardware tests we have found that errorfree interrupt performance can not be guaranteed when sharing interrupts ECANI1000HR CAN Bus Interface 14 RTD Embedded Technologies Inc Chapter 3 BOARD INSTALLATION The ECAN1000HR CAN bus interface board is very easy to connect to your industrial disributed control system Direct interface to 104 systems as well as EUROCARD boards is possible This c
11. SA ECANI1000HR CAN Bus Interface 30 RTD Embedded 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 AN
12. ans that you should also 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 re entrant Of course there are ways to avoid this problem such as those which activate when your ISR is called Such solutions are however beyond the scope of this manual 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 e Push any processor registers used in your ISR Most C compiler do this automatically e Put the body of your routine here e Read interrupt status register of the SJA1000 chip on your ECAN1000HR board e Clear the interrupt bit by writing to the SJA1000 CAN controller e Issue the EOI command to the 8259 by writing 20h to address 20h e Pop all registers Most compilers do this automatically CAN Bus Interface 25 RTD Embedded Technologies Inc The following C example shows what the shell of your ISR should be like Function new IRQ handler Inputs
13. dress Selection JPI Figure 1 Component Locations Base Address Jumpers Factory setting 300h The ECAN1000HR is I O mapped into the memory space of your host XT AT This board occupies two I O addresses 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 I O space is already occupied by other devices and memory resident programs When the ECAN1000HR attempts to use it s own reserved memory addresses which are being already used by another peripheral device erratic performance may occur and the data read from the board may be corrupted To avoid this problem make sure you set up the base address by using the ten jumpers marked BASE This allows you to choose from a number of different CAN Bus Interface 12 RTD Embedded Technologies Inc addresses in your host computer I O map Should the factory installed setting of 300h be incompatible to 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 form Ensure that 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 board record the setting inside the back cover of this manual BASE ADDRESS JUM
14. er field devices Connectors Galvanically isolated CAN bus 90 degree 10 pin header Host bus XT AT PC 104 bus Electrical Operating temperature range 40 to 85 Supply voltage 5V 8 Power consumption 1 0W typical CE The ECAN1000HR is CE certified in the IDAN Enclosure System Please consult the factory for more information on the system CAN Bus Interface 29 RTD Embedded Technologies Inc Chapter 7 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 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 U
15. f you have any problems with installation or use of the board contact our Technical Support Department 814 234 8087 during European business hours Alternatively send a FAX to 814 234 5218 or Email to sales rtd com When sending a FAX or Email request please include the following information Your company s name and address your name your telephone number and a brief description of the problem ECANI1000HR CAN Bus Interface 10 RTD Embedded Technologies Inc Chapter 2 BOARD SETTINGS The ECAN1000HR CAN bus interface board has jumper settings which can be changed to suit your application and host computer memory configuration The factory settings are listed and shown in the diagram at the beginning of this chapter Factory Configured Jumper Settings Table 1 below illustrates the factory jumper setting for the ECAN1000HR Figure 1 shows the board layout of the ECAN1000HR and the locations of the jumpers The following paragraphs explain how to change the factory jumper settings to suit your specific application Table 1 Factory configured jumper settings Please see figure 1 for detailed locations JUMPER NAME DESCRIPTION NUMBER OF JUMPERS FACTORY SETTING JP1 BASE Base Addresses 8 300H me CAN bus termination Table 1 Factory configured jumper settings ECANI1000HR CAN Bus Interface 11 RTD Embedded Technologies Inc e CAN Bus Connector Fuse F1 000 DC1 J34 CAN Bus Termination Ad
16. hapter gives step by step instructions on how to install the ECAN1000HR into your system After completing the installation it is recommended that you use the diagnostic and test software to fully verify that your board is working Board Installation Keep your board in the 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 handle 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 2 reviews the factory settings and how to alter them If any alterations are needed please refer to the appropriate instructions in this chapter Do however note that incompatible settings can result in unpredictable board operation and erratic response General installation guidelines Turn OFF the power to your computer and all devices connected to the ECAN1000HR e Touch the grounded metal housing of your computer to discharge any antistatic build up and then remove the board from its antistatic bag e Hold the board by the edges and install it in an enclosure or place it on the table on an antistatic surface e Connect the board to the CAN fieldbus using the fieldbus interface header connector J12 Make sure that the orientation of the cable is correct Installation integrated with a PC 104
17. he IMR is arranged so that bit O is for IRQO and bit 7 is for IRQ7 See the paragraph entitled nterrupt 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 ECANI1000HR CAN Bus Interface 26 RTD Embedded Technologies Inc 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 IRQ1 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 interrupt sources program it to do that Finally clear the mask bit for your IRQ in the IMR This will enable your IRQ Common Interrupt mistakes Remember that hardware interrupts are from 8 15 XT IRQ s are numbered 0 7 Forgetting to clear the IRQ mask bit in the IMR Forgetting to send the EOI command after ISR code disables further interrupts ECANI1000HR CAN Bus Interface 27 RTD Embedded Technologies Inc Example on Interrupt vector table setup in C code void far interrupt new_IRQ1_handler void ISR function prototype
18. ips Semiconductors The SJA1000 internal message FIFO RAM provides storage for 64 message bytes Each message can vary from one to up to 8 bytes in length Each message object has a unique identifier and can be configured to either transmit or to receive 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 SJA1000 also features masking 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 specifical message identification strategy There are separate global masks for standard and extended frames The incoming message first passes through the global mask and is then matched to the identifiers in the message objects CAN Bus Interface 19 RTD Embedded Technologies Inc Galvanic isolation of the CAN bus The galvanic isolation of the ECAN1000HR is implemented using the following Optocouplers for reliable data transmis
19. of company changed reformatted 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 Ma chines 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 CAN Bus Interface 5 RTD Embedded Technologies Inc TABLE OF CONTENTS CHAPTER 1 INTRODUCTION iiss EDS oie 8 tt ebd bet d Ate 8 BUS CONTROLLER eT eee 8 PHYSICAE INTERFACE 55 9 MECHANICAL DESCRIPTION 9 CONNECTOR DESCRIPTION ineat e S ee ete rep te RR ERE Sel DL a 9 WHAT COMES WITH YOUR BOARD
20. of the ECAN1000HR J34 Galvanically isolated CAN bus termination jumper The jumper marked as J34 is the CAN bus termination jumper Only two termination jumpers should be closed at the endpoints of the CAN bus Failure to do so may degrade the performance of the bus and it will affect the bus timing characteristics of the CAN bus The maximum guaranteed drive capability of the CAN bus transceiver is 32 nodes CAN Bus Interface 17 RTD Embedded Technologies Inc Chapter 4 HARDWARE DESCRIPTION This chapter describes in detail the major features of the ECAN1000HR e The Philips SJA1000 CAN bus controller e Galvanic isolation of the CAN bus CAN BUS TERMINATION 120 OHMS SJAIOOO CAN BUS CONTROLLER 4 BUS ADDRESS DECODER Figure 6 ECAN1000HR Block diagram ECANI1000HR CAN Bus Interface 18 RTD Embedded Technologies Inc The CAN bus controller The SJA1000 CAN bus controller uses a 16 MHz base oscillator This must be taken into account when performing settings in the CAN bus timing registers that set the baud rate and sampling times of the CAN network The SJA1000 CAN controller consists of seven functional blocks The host interface logic the Transmit Buffer the Receive Buffer the Acceptance Filter the Bit Stream Processor the Bit Timing Logic and the Error management logic A detailed description of these blocks is listed in the detailed component specific datasheet reprinted from Phil
21. owledged 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 interrupt handlers When an interrupt request line is driven high by a peripheral device such as the ECAN1000HR the interrupt controller checks to see if interrupts are enabled for that IRQ It 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 if 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 is popped from the system stack and the program execution continues from the point where the interruption occurred ECANI1000HR CAN Bus Interface 23 RTD Embedded Technologies Inc Using Interrupts 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 unde
22. r 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 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 sub routines 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 ECAN1000HR by writing to the SJA1000 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 prog
23. ram 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 your 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 and exit the routine with the IRET instruction instead of the RET instruction ECANI1000HR CAN Bus Interface 24 RTD Embedded Technologies Inc 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 re entrant 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 Consider then the following situation in your program If DOS function X is being executed when an interrupt occurs and the interrupt routine makes a call to the same 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 operations The general rule is that do not call any functions that use the screen read keyboard input or any file I O routines These should not be used ISR s The same problem of re entrancy also exists for many floating point emulators This effectively me
24. rily halt its current process and execute another routine Upon completion of the new routine control is returned to the original 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 whilst waiting for a keystroke to occur Thus the interrupt scheme is used and the processor proceeds with other tasks When a keystroke finally occurs the keyboard then interrupts the processor so that it can get the keyboard data It then places it into the memory and then returns to what it was doing before the interrupt occurred Other common devices that use interrupts are A D boards network boards serial ports etc Your ECAN1000HR can interrupt the main processor when a message is received or transmitted if interrupts are enabled on the ECAN1000HR board By using interrupts you can write powerful code to interface to your CAN network 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
25. roller This controller supports CAN Specification 2 0 This versatile chip supports standard and extended Data and Remote frames 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 The internal 64 byte receive FIFO is ideal for block mode data transfer from the CAN controller chip CAN Bus Interface 8 RTD Embedded Technologies Inc Physical Interface Industrial environments require galvanic isolation and bus filtering to provide reliable data communication and safety The galvanivally isolated physical interface is uses high speed optocouplers and a DC DC converter To protect the input from radiated bus noise a specially balanced bus filter is used The bus connectors conform to the ISO11898 2 specification For more information on CAN bus please visit the CAN in Automation Website at http www can cia de Mechanical description The ECAN1000HR is designed on a PC 104 form factor An easy mechanical interface to both PC 104 and EUROCARD systems can be achieved Stack your ECAN1000HR directly on a PC 104 compatible computer using the onboard mounting holes Connector description There is a 10 pin interface connector on the ECAN1000HR to directly interface to the galvanivally isolated CAN networks This header is compliant with the ISO11892 2 specified pinout Wha
26. s 2 bytes of host PC I O memory space This 3 byte window is freely selectable by the user as described in Chapter 2 Table 2 After setting the base address you have access to the internal resources of the SJA1000 CAN controller chip These resources are described in the next sections reprinted from the SJA1000 chip specific user s manual ADDRESS Description BASE 00h ADDRESS BASE 01h DATA of ADDRESS BASE 02h HARDWARE RESET OF SJA1000 Table 5 ECAN Memory Map The SJA1000 chip access is multiplexed in such a way that the host must first write to BASE 0 the internal address of the CAN chip and after that perform a write to address BASE 1 with the actual data to be written into the desired memory location An example is listed below using syntax We assume base address is 300H Write 78H to the CAN controller Control byte located in the on chip address 0 outp 0x300 0x00 outp 0x301 0x78 Address BASE 02h is hardware reset function of the SJA1000 Performing a read or write to this address will cause a hardware reset to the CAN controller You may need to reset the chip in case of an unrecoverable error in the CAN controller chip On the following pages is attached the chip specific user s manual for the SJA1000 CAN controller chip ECANI1000HR CAN Bus Interface 21 RTD Embedded Technologies Inc INTERRUPTS What is an interrupt An interrupt is an event that causes the processor in your computer to tempora
27. sion e DC DC converter to supply power to the CAN bus and the physical interface circuitry The high speed optocouplers are directly connected to the SJA1000 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 choke also reduces the radiated emissions in the range of 30 200MHz 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 A 125mA fuse green are used to protect the DC DC converter The jumper marked as J34 is the CAN bus termination jumper Only two termination jumpers should be closed at the endpoints of the CAN bus Failure to do so may degrade the performance of the bus or even cause permanent damage to the driver chips The maximum drive of the transceiver is 32 nodes ECANI1000HR CAN Bus Interface 20 RTD Embedded Technologies Inc Chapter 5 BOARD OPERATION AND PROGRAMMING This chapter shows you how to program and use your ECAN1000HR It provides a complete description of the internal memory map of the chip and a detailed discussion of the internal registers to aid you in programming your CAN controller chip The full functionality of the ECAN1000HR is described in the attached datasheet reprint from Philips on the SJA1000 CAN controller chip Defining the Memory Map The memory map of the ECAN1000HR occupie
28. sunecessnsccessans 18 THE CAN BUS CONTROLLER inde ege cei tere Drive es eee veu er e A 19 GALVANICTSOLATION OF THE CAN BUS ASA niece A 20 CHAPTER 5 BOARD OPERATION AND PROGRAMM ING ssssssssesssseesssseesssssessssseesssscesssecesaseeessees 21 DEFINING THE MEMORY MAP sic eet oic adde a t trn cc ides 21 INTERRUPTS sve rer e dre are dr Tes 22 What is an interrupt Lege ue e EF DER SE ER eR S ER e ELA RO REFER OR e Ee P Ever Ro tese EE 22 l terr ptrequest eet dE tecti Saat cae e ere e Yea detec es 22 8259 Programmable Interrupt Controller eee eee eese ener nenne ennemi 23 Interrupt Mask Register IMR cesses 23 End of Interrupt EOI Command 23 What exactly happens when an interrupt occurs eese nennen retener teet nene 23 Using Interrupts in your DIOR IVAN RE e Eae 24 Saving the Startup Interrupt Mask Register IMR and interrupt 26 Common Interrupt mistak s sott e nq a epp re ee OPE e UE Ree e 27 Example on Interrupt vector table setup in C code eese eene nennen eene enne ene 28 CHAPTER 6 ECAN1000HR 5 8 2 00 00 00 0440 29 HOST INTERFAGE o
29. t comes with your board Your ECAN1000HR package contains the following items ECAN1000HR CAN bus interface module e User s manual Note Software and drivers can be downloaded from our website If any item is missing or damaged please call RTD Embedded Technologies Inc customer service department at the following number 814 234 8087 CAN Bus Interface 9 RTD Embedded Technologies Inc Board accessories In addition to the items included in your ECAN1000HR delivery several software and hardware accessories are available Contact your local distributor for more information and for advice on selecting the most appropriate accessories to support your system Application software drivers QNX e Hardware accessories including IDAN solid aluminium frames for PC 104 based computers For more information on IDAN please visit our websites at the following website addressses www rtdfinland fi or www rtd com Using this manual This manual is intended to help you install your new ECAN1000HR card and get it working quickly whilst also providing enough detail about the board and it s functions so that you can obtain maximum use of it s features even in the most demanding applications This manual does not cover CAN bus network programming and system design 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 I
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