A Discussion of CAN Operations and ISO 15765 Processing (PDF
Contents
1. Buffer time out op flag bit 3 set flow control frame received Buffer time out op flag bit 4 set flow control frame waiting to be loaded Buffer time out op flag bit 5 set transmit object triggered Buffer time out op flag bit 6 set not used Buffer time out op flag bit 7 set not used Buffer time out no op flags found Receive mode first frame received large buffer not available Consecutive frame buffer not assigned Consecutive frame buffer number not valid Flow control frame buffer not assigned Flow control frame buffer number not valid Buffer service counter failure zero Buffer service counter failure not valid Transmit service counter failure zero Transmit service counter failure not valid Time out flushing TX1 command TX1 command pending timed out TXO command pending timed out Time out flushing 1X command Buffer time out buffer number mode byte and flag byte follow Advanced Vehicle Technologies Inc Page 22 Summary Legacy mode version 5 8 and below e I5P is enabled disabled globally e AE is enabled disabled globally e All objects are paired to only one object e The designated object is used to send a flow control frame e A received flow control frame is not associated to a specific transmit object e Only one buffer available used for both transmit and receive functions e User must set up all receiv2. 3 ww xx ID of the message 11 22 33 44 data field The AVT unit removed the PCT byte value of 04 and removed all pad bytes if any Example 2 Transmit the following message onto the network using object 6 Message ID yy zz Data field 12 34 56 78 90 Send the following command to the AVT unit 08 06 yy zz 12 34 56 78 90 Receive the following response when the message has been successfully transmitted 82 09 06 The AVT unit checks the length of the data field computes the PCT byte constructs the CAN frame adds pad bytes if enabled and transmits the frame or frames onto the network Example 3 Transmit the following message onto the network Message ID yy zz Data field 12 34 56 78 90 AB CD EF 11 12 13 14 15 16 17 18 Send the following command to the AVT unit 11 13 06 yy zz 12 34 56 78 90 AB CD EF 11 12 13 1415 1617 18 Advanced Vehicle Technologies Inc Page 15 Receive the following response when the message has been successfully transmitted 82 09 06 The data field is more than 7 bytes The AVT unit will handle the multi frame messaging required Additional Information A separate document was prepared for several customers about ISO 15765 processing for AVT 418 and AVT 718 firmware version 5 9 and above The contents of that document follow It is pretty much the same information as provided above but it may be presented in a different manner and different issues were of concern Questio
3. Example Setup A number of assumptions have been made for this example A real application may be different Select CAN mode of operation E1 99 Select the baud rate 72 OA xx Setup and enable object 3 for receive 77 05 03 01 01 00 ww xx 73 04 03 O1 Setup and enable object 6 for transmit operations Necessary if a flow control frame must be transmitted 77 05 06 10 01 00 yy zz 73 04 06 10 Enable ISO 15765 message processing Objects 3 and 6 are paired object 6 is the designated transmit object normal addressing is used 73 28 03 06 Advanced Vehicle Technologies Inc Page 14 Select the physical layer CAN C CAN B or SWC 72 11 xx Note the order The physical layer is selected last This prevents receiving any messages from the network before all the setup has been completed which might cause errors or unexpected operations The AVT unit will monitor all received messages and process them according to ISO 15765 rules A received message will generally be of the form Ox Oy jj kk aa bb cc Ox count of bytes to follow Oy object number 1 to F jj kk 11 bit arbitration field right justified aa bb cc data from object A complete list of received message formats is in the Master Commands and Responses document Example 1 An ISO 15765 message is received from the network 07 03 ww xx 11 22 33 44 07 indicates from the network 7 bytes follow 03 message received from object
4. Page 21 Receive mode consecutive frame buffer assigned but not in use Receive mode consecutive frame sequence number error Receive mode flow control frame separation time invalid Receive mode DLC gt 7 in single frame processing Receive mode DLC gt 6 in single frame processing Receive mode DLC gt 6 in first frame processing Receive mode DLC 0 Receive mode DLC 1 with extended addressing enabled Time out forwarding message to host Receive mode FFDL 0 Transmit mode buffer time out Transmit mode error decoding op mode flags Transmit mode buffer underrun on first frame Buffer and object numbers follow Transmit mode invalid flow status received operation aborted Buffer and object numbers follow Transmit mode flow status 2 received operation aborted Buffer and object numbers follow Transmit mode flow status 1 wait count max operation aborted Buffer and object numbers follow Transmit mode buffer count 0 on first frame operation aborted Buffer and object numbers follow Buffer manager buffer mode value wrong Receive mode first frame DLC too short Received a flow control frame not expecting one Buffer time out op flag bit 0 set long message first frame waiting Buffer time out op flag bit 1 set waiting for flow control frame Buffer time out op flag bit 2 set consecutive frames are in progress
5. mews O o o books 8 S Kps a 8 O wa a o g 0500 tps o l e o no cee o as tps iar oo o o a S oo o ow f os O r O The user can also write directly to the two bit timing registers to set a desired baud rate and characteristics This is done using the 73 OB xx yy command When this method is used the baud rate query will return 82 0A 00 The 00 value indicates that the user has set the baud rate by writing directly to Bit Timing Registers 0 and 1 Ford HS CAN High Speed CAN 500 kbaud The following baud rate command is recommended 73 0B 40 2B instead of the 72 0A 02 setting listed above Ford MS CAN Medium Speed CAN 250 kbaud The following baud rate command is recommended 73 0B C1 58 instead of the 72 OA 03 setting listed above Ford MS CAN Medium Speed CAN 125 kbaud The following baud rate command is recommended 73 0B C3 58 instead of the 72 0A 04 setting listed above Baud Rate Technical Details A CAN network can be operated at nearly any baud rate or speed up to 1 Mbps The actual bit time on a CAN network using the 82527 device is determined primarily by three parameters Baud rate prescaler TSEG1 and TSEG2 The operating bit time baud rate is determined by the values these parameters are programmed to For detailed information consult the Architectural document referenced previously Bit timing registers 0 and 1 contain the three primary parameters that cont
6. mm nn message ID Ae optional address extension byte pp qq actual data bytes of the message e The AVT 418 718 will handle all the necessary operations to properly send the message onto the network using the ISO 15765 protocol Receiving a message from the network e Depending on how many data bytes were received the AVT 418 718 will inform the host using one of three possible forms The general form is described here Details are provided below e Total count of bytes that follow Ox or 11 xx or 12 xx yy one two or three bytes Advanced Vehicle Technologies Inc Page 19 e The object number the message was received through If 29 bit ID was used bit 7 is set one byte e The message ID one byte e AE byte if used one byte e All of the message data e PCI bytes are omitted e Pad bytes are omitted Examples gt Ox tt mm nn ae pp qq Ox count of number of bytes that follow rr object number message was received through mm nn message ID Ae optional address extension byte pp qq actual data bytes of the message gt or 11 xx tt mm nn ae pp qq XX count of number of bytes that follow rr object number message was received through mm nn message ID Ae optional address extension byte pp qq actual data bytes of the message gt or 12 Oy xx tt mm nn pp qq xx yy count of number of bytes that follow rr object number message was received through m
7. gt 8211 02 Two wire CAN mode Set up Object 1 as a transmit object 7705 01 100105 0357 gt 8705 01 10 01 00 03 57 Object setup object 1 transmit 11 bit arbitration field data length 00 ID 03 57 770601 F1 E2 D3 C4 B5 gt 870601 F1 E2 D3 C4 B5 Object data setup object 1 data Fl E2 D3 C4 B5 Setting the object data field updates the data length 73040110 gt 830401 01 Object status object 1 enabled as transmit Advanced Vehicle Technologies Inc Page 6 Set up object 2 as a receive object 7705 02 01 01 00 03 57 gt 8705 02 01 01 00 03 57 Object setup object 2 receive 11 bit arbitration field data length 00 ID 03 57 gt 73040201 gt 83040201 Object status object 2 enabled as receive Transmit a message from one interface unit 73070101 Transmit object 1 from one interface unit The other interface unit will receive the message in object 2 Two responses from the transmitting interface unit gt 83070101 Confirmation of the transmit command gt 820901 Object 1 successfully transmitted Receive a message at the other interface unit Receive the response gt 08 02 03 57 F1 E2 D3 C4 B5 Received message from the network through object 2 ID 03 57 data bytes follow and are F1 E2 D3 C4 B5 A Transmit Example The following example demonstrates setting up an object for transmission and then transmitting a m
8. the Master Commands and Responses document CAN operations section Document file name is MASTERxx PDF where xx is the version number of the document and is available from the App Notes section of the Download page of our web site http www AVT HQ com download htm What do configure in an object The user must set several parameters of the object Examples are provided for both transmit and receive operations e Arbitration field or Message ID e Transmit or receive e Note that data field length is not important is actually ignored should be set to 00 e Enable or disable the object Arbitration fields are not even bytes in length How do use them The arbitration fields are either 11 bits or 29 bits in length When setting either the upper most bits are zeros Examples An 11 bit arbitration field is 101 0110 1011 In hex digits 05 6B A 29 bit arbitration field is 1 1001 1011 0111 1000 0101 1101 0110 In hex digits 19 B7 85 D6 Network Speed The AVT 418 512 717 and 718 support two methods to set the network baud rate Preprogrammed and user defined There are numerous preprogrammed baud rates that can be chosen using the 72 0A xx command The table below contains the available baud rates as well as the values that are written to the two bit timing registers This is provided as a reference to the user Register values are in hex Advanced Vehicle Technologies Inc Page 4 ar ee eee ee o Oo oo
9. 72 2701 Enable ISO 15765 message padding Default All data fields are 8 bytes long Default pad byte value is 00 73 27 O1 xx Enable ISO 15765 message padding xx pad byte value Using ISO 15765 Processing Enable ISO 15765 processing after entering CAN mode Setup and enable both the transmit and receive objects of the pair No action is required to receive an ISO 15765 message from the network regardless of length The AVT interface will remove the PCT control byte and any pad bytes from a received message If enabled the AVT interface will leave the address extension byte in the data field Do not include the PCI control byte in the data field of a message to be transmitted Do not include any pad bytes in the data field of a message to be transmitted No special action is required to send a message regardless of length To transmit a message to the network the user must use the short form transmit command Data lengths from 00 to 4095 bytes are supported Normal or extended addressing is supported There are a range of transmit commands available to the user A complete list is provided in the Master Commands and Responses document If address extension is enabled include the AE byte as the first byte of the data field Periodic messages transmitted by the AVT unit both Type0 and Type1 are not subjected to ISO 15765 processing The data field of those messages must be properly configured by the user
10. AJE ADVANCED VEHICLE TECHNOLOGIES Inc 4 December 2005 A Discussion about CAN The AVT 418 AVT 512 AVT 717 and AVT 718 all support a single channel of CAN Controller Area Network operations This document provides a brief description of how the CAN network interface on our interface units is implemented and used Included in this document are details on some of the CAN commands and technical implementation details with respect to the CAN network and AVT interface units Reference Documentation The reader should consult other sources for detailed information on the architecture operation and implementation of CAN networks Available from Intel is the PDF document 82527 Serial Communications Controller Architectural Overview File name 27241003 PDF This document contains very good information on the operation of a CAN network details on the global masks and setting up and using the objects Test and Development Considerations CAN operations require a network consisting of a minimum of two nodes in order to transmit a message This becomes important in development integration and testing Silicon All AVT interface products use the Intel 82527 CAN controller device to implement the CAN network interface Physical Layer The AVT 418 and AVT 718 supports three different physical layer implementations of CAN e 2 wire CAN also known as ISO 11898 J1939 or CAN C e 2 wire CAN also known as ISO 11519 or C
11. AN B e Single Wire CAN known as J2411 or SWC The AVT 512 and 717 support two implementations for the physical layer of CAN e 2 wire CAN also known as ISO 11898 J1939 or CAN C e Single Wire CAN known as SWC and J2411 The original Bosch CAN specification does not specify the baud rate or physical layer 1509 Manor View Road Davidsonville MD 210385 USA 1 410 798 4038 voice 1 410 798 4308 fax www AVT HQ com suppornt AVT HQ com Physical Layer The most common implementation is a balanced signal or 2 wire network known as ISO 11898 J1939 CAN C and possibly other names For this implementation the Philips 82C250 transceiver is used Later versions of AVT 718 and AVT 418 hardware use the Philips TJA1050T transceiver for better performance and EMI considerations Some AVT 512 units may be equipped with Philips 82C251 transceiver The physical layer to be used is selected through a software command Refer to the Master Commands and Response document for the command specifics Refer to the individual unit User Manual for signal and pin definitions What are the different parts of a CAN message A CAN message consists of a maximum of 108 bits CAN 1 0 or 128 bits CAN 2 0B All of the bits are identified in the specification Only the Arbitration and Data fields are of interest A diagram of a CAN 2 0B message frame is included at the end of this document The diagrammed frame references SAE specific
12. O 15765 and others do not The 7x 28 command was developed to address the shortcomings of the other command The 7x 28 command is used to declare an object pair When an object pair is declared ISO 15765 processing is enabled for the pair of declared objects only All other objects are not affected It is possible to declare multiple receive objects and pair them with the same transmit object For example the user may set up three receive objects and one transmit object Each of the receive objects can be paired with the one transmit object This is done by issuing three 7x 28 commands one for each of the receive objects and using the same transmit object in each command Message Padding Some CAN networks require that all CAN frames be full length This is done by padding the data field with extra bytes if necessary to create a full frame With ISP enabled the user can enable or disable frame padding The 7x 27 command is used to enable frame padding and the user can specify the value of the pad byte The AVT interface will then pad the data field if necessary The AVT interface will not confuse the data bytes from the pad bytes that is a function of ISO 15765 processing Advanced Vehicle Technologies Inc Page 13 The 7x 27 command disables or enables the message padding feature only when the ISO 15765 function is enabled That command is 71 27 ISO 15765 message padding status query 72 27 00 Disable ISO 15765 message padding
13. VT 418 and AVT 718 firmware version 5 1 and above incorporate ISO 15765 messaging support The user does not need to keep track of data length or frame types to send or receive messages The firmware handles all functions involved in transmitting or receiving ISO 15765 formatted messages The term ISO 15765 may be referred to as ISP here Command Summary Enable Disable The ISO 15765 function is enabled by the user with the 7x 26 or 7x 28 commands The 7x 28 command was first available in firmware version 5 9 It is the recommended command to enable I5P functionality The 7x 26 command function was implemented in early firmware versions It is not recommended for new designs Only use one command to enable ISO 15765 processing Do not use both commands Do not enable any Auto Respond Objects if ISO 15765 processing is enabled Object 15 0F does NOT support ISO 15765 processing 7x 28 Command Recommended ISO 15765 Processing Command 71 28 Object pairing status query Default is no objects are paired 72 28 Ox Disable ISO 15765 processing for object Ox and it s pair 73 28 Ox Oy Declare objects Ox and Oy as paired Enable ISO 15765 processing for the pair Address extension is disabled for the pair Object order is not important 74 28 Ox Oy ww Declare objects Ox and Oy as paired Enable ISO 15765 processing for the pair Enable address extension and use byte ww in flow control frame Advanced Vehicle Tec
14. ation J1939 and uses the term PDU in place of arbitration field Arbitration Field In the automotive industry CAN arbitration fields are more commonly known as Message IDs The arbitration field serves to define the priority of a message relative to all other messages In CAN a zero bit has higher priority than a one bit Therefore a message with a lower value arbitration field has a higher priority than a message with a higher value arbitration field The arbitration field can be used to indicate what kind of data the message contains It can also be used to indicate the to address for the message Data Field The data field of a message can contain from zero to eight bytes of user defined data What kinds of CAN are there There are two major versions of CAN They are CAN 1 0 and CAN 2 0B CAN 1 0 messages have 11 bit arbitration fields CAN 2 0B messages have 29 bit arbitration fields Both versions can coexist on the same network AVT CAN interface units can support operations for either message type A node can only transmit and or receive messages for which it is set up On AVT interface boards there are fifteen objects Each object is independent can support either format and can be setup as required Advanced Vehicle Technologies Inc Page 2 What is an Object The AVT interface unit using the Intel device communicate on the CAN network using what are known as objects Each obje
15. bitration field 00 Data length not used 16 B7 C8 D9 Arbitration field Enable the object 73040C 01 gt 83040C 01 Notification that a message has been received 11 bit arbitration field Response Ox OC aa bb cc rr ss tt vv xx Explanation Ox Message from the bus upper nibble 0 Byte count to follow lower nibble x OC Object number aa bb cc ID of received message 11 bit arbitration field rr ss tt vv xx Received data Notification that a message has been received 29 bit arbitration field Response Ox 8C aa bb cc dd rr ss tt vv xx Explanation Ox Message from the bus upper nibble 0 Byte count to follow lower nibble x 8C Object number is C 8 indicates a 29 bit arbitration field aa bb cc dd ID of received message 29 bit arbitration field rr ss tt vv xx Received data gt Note that the alternate header format of 11 xx will be used if the byte count exceeds OF Advanced Vehicle Technologies Inc Page 9 A Receive Everything Example The following example demonstrates setting up object 15 to be able to receive every 11 bit ID message on the network If other objects are set up as receive object 15 will receive all messages NOT received by any other receive objects Object 15 is selected to receive all network messages since it cannot be set as a transmit object In order to receive all messages on the network the message mask must be set to all zeros If any o
16. bjects are set as transmit the Global Mask 7x 01 or 7x 02 commands should NEVER be set to all zeros This could result in a transmit object repeatedly transmitting a message without delay and without stopping the so called babbling idiot failure Refer to the Intel 82527 document referenced on the next page for a detailed explanation of how this could happen This example is not related to the previous demonstration All commands are shown Responses are in italics Select CAN mode of operation E199 gt 91 10 Select the baud rate 72 OA xx gt 82 0A xx where xx is the baud rate according to the list of available baud rates as listed in the Master Commands and Responses document Select the physical layer CAN C CAN B or SWC 72 11 xx gt 82 11 xx where xx is the mode selection according to the list of modes in the Master Commands and Responses document Set object 15 message mask to all zeros 75 03 00 00 00 00 gt 85 03 00 00 00 00 Set up object 15 79 05 OF 01 zz 00 00 00 00 00 gt 8905 OF 01 zz 00 00 00 00 00 79 header byte 7x command 9 bytes follow 05 command type OF object number 01 receive zz arbitration field length zz 01 for 11 bit arbitration field zz 10 for 29 bit arbitration field 00 data length this is not important 00 00 00 00 arbitration field value Enable object 15 73040F 01 gt 83 040F 01 At this point all network messag
17. ct can be thought of as a mailbox through which a message is transmitted or received Each object or mailbox can only transmit or receive not both simultaneously The Intel device has 15 objects numbered 1 to 15 1 to F available Object 15 F can only conduct receive operations Objects 1 to 14 can be configured for either transmit or receive operations one object can not support simultaneous receive and transmit functions Each object must be configured properly and enabled before it can be used What is Configured Automatically The AVT interface automatically configures some CAN parameters when CAN mode is entered or when the CAN device is commanded to be reset 21 06 Some of the parameters are listed here e The input clock is 16 MHz e The DSC bit is set to 1 This sets the SCLK system clock to 8 MHz e Both Global Masks are set to all 1 s This is a must match condition e All objects are disabled and ID s are set to all 1 s e The CAN network data rate or speed is set to 250 kbps Details on network speed setting are provided later in this document e On the AVT 418 and AVT 718 the interface is physically disconnected from the network What do have to Configure The user must initialize the following parameters to utilize the CAN network e Global Mask 11 bit only if necessary e Global Mask 29 bit only if necessary e Each object that is to be used e The network bau
18. d rate e Select the physical layer How is a message received When a message is received it s ID is matched against the arbitration fields of all objects that are enabled setup for receiving and have the same arbitration field length If the message ID matches an object arbitration field that message is received by that object and forwarded to the host computer What is a Global Mask The ID of a received message including a message being transmitted is passed through a global message mask logical AND before being compared to the ID of each enabled object Advanced Vehicle Technologies Inc Page 3 There are two global message masks One is for 11 bit arbitration field messages The other is for 29 bit arbitration field messages The bits in the global masks determine what bits in a message ID are must match or don t care when compared to an active object s arbitration field A O bit in the global mask designates that bit as a don t care bit when compared to an object arbitration field A I bit in the global mask means that bit in the message ID must match the object arbitration field A global mask set to all 1 s means the incoming message ID must match exactly the object arbitration field The proper use of the global message masks permits the user to set up an object to receive a class or group of messages through a single object What commands are available Refer to
19. e assumed that multi frame messages will exist That requires every object to or from the network to have an associated opposite function object from or to the network Hence an object pair One object of the pair must be configured to receive The other object must be configured to transmit The user must set up the transmit object with the correct message ID For completeness the Address Extension AE byte exists in all commands The declared AE byte is only used in transmitting a flow control frame The new command to support these enhanced operations is the Pairing command 7x 28 A description of the pairing command follows Some sequence of event listings are provided to illustrate how the host computer might use this new function and command NOTE AVT 418 and AVT 718 firmware is identical I5P_ Pairing Command It is implicit in this command that if an object pair is declared messages through both of the objects are processed according to the ISO 15765 protocol If an object is not paired then it is processed normally ISO 15765 processing is disabled for that object The order of the pairing is not important Object 0x may be the receive or transmit object One object of the pair must be configured to receive The other object must be configured to transmit The transmit object must be set up with the proper message ID The user is responsible for properly setting up and enabling each object of th
20. e objects e User should set up designated transmit object e Transmit short form commands are I5P processed e Transmit long form method bypasses I5P processing e A transmit ack 82 09 Ox will be sent to the host when the AVT unit transmits a flow control frame This was an error The AVT unit should not have done this Version 5 9 and above do not send the host this message Advanced Vehicle Technologies Inc Page 23 SOF ACK Field 2 bits PDU oc DLC Data Field CRC PDU s 18 bits oc 4 bits 0 to 64 bits 16 bits 11 bits r rO SRR IDE EOF 7 bits J1939 Frame CAN 2 0B Frame Construction PDU Protocol Data Unit construction 29 bits each x one bit Priority rsvd data page Format 1 byte Destin addr 1 byte Source addr 1 byte XXX 0 XxX XXXXXXXX XXXXXXXX XXXXXXXX PGN Parameter Group Number construction 24 bits each x one bit not used rsvd data page Format 1 byte Destin addr 1 byte XXXXXX 0 xX XXXXXXXX XXXXXXXX Advanced Vehicle Technologies Inc Page 24
21. e pair This must be done before issuing the pairing command Advanced Vehicle Technologies Inc Page 17 Commands and Responses e 7128 Report all object pairs Response if none exist 82 28 00 Response if any exist 83 28 0x Oy or 84 28 Ox Oy AE All objects are reported if any exist e 722800 Delete all object pairs Response 82 28 00 e 72 28 0x Delete one object pair Response 82 28 0x e 73 28 0x Oy Configure objects Ox and Oy as a pair AE is disabled Response 83 28 0x Oy e 74280xO0yAE Configure objects Ox and Oy as a pair Use AE for any response frames Response 84 28 Ox Oy AE Object order is not important Sequences of Events Initial Setup e Enter CAN mode E1 99 e Select baud rate 72 0A xx e Select physical layer 72 11 xx e Operations commence from this point Initialize Enable and Declare an object pair e Determine receive object Or to be used and the message ID for that object e Determine the transmit object Ot to be used and message ID for that object e Determine if AE is used if not ignore this if so determine AE byte value e Setup the receive object 7x 05 Or 01 J e Setup the transmit object 7x 05 Ot 10 Declare the object pair 7x 28 Or Ot or 7x 280tOr Enable the transmit object 73 04 Ot 10 e Enable the receive object 73 04 Or 01 e All messages from the network with the specified ID will be received I5P processed and sent to the host at
22. ersion 3 0 and above offer a short form transmit command To use this command the user must have selected the baud rate and physical layer prior to issuing the transmit command No other setup to transmit is required An example of the short form transmit command is provided here 06 06 03 C4 1A 2B 3C gt 820906 Command explanation 06 Header byte 0 to the network 6 six bytes follow 06 0 11 bit arbitration field 6 object number 03 C4 Arbitration field 1A 2B 3C Data field 3 bytes Response explanation 82 8 command response 2 two bytes follow 09 Transmit status report object transmission successful 06 Object number Advanced Vehicle Technologies Inc Page 8 A Receive Example The following example demonstrates setting up an object to receive a message Object 12 is used here This example is not related to the previous example or the demonstration All commands are shown Responses are in italics Set up the Global Message Masks as required Default status is recommended 11 bit mask 73 01 xx yy gt 8301 xx yy 29 bit mask 75 021rssttvv gt 85 02 rr ss ttvv Disable the object if necessary 73 040C 00 gt 83 040C 00 Set the object configuration 79 05 OC 01 1005 16 B7 C8 D9 gt 8905 0C 01 10 05 16 B7 C8 D9 Explanation 79 OS Command upper nibble 7 byte count lower nibble 9 and command type 05 OC Object number Ol Receive 10 29 bit ar
23. es will be received by object 15 and sent to the host Note The AVT interface never sends to the host computer any message it transmits Advanced Vehicle Technologies Inc Page 10 A Keep Alive Example Problem You need to send the module under test a Keep Alive message every second You also need to send the module specific messages during the testing All of these messages use the same message ID or arbitration field How to do this Wrong Method e Declare object 1 as a transmit object and use it to transmit your test messages e Declare object 2 as a transmit object Load it with the keep alive message Set object 2 for Type0 Periodic message This will not work because e You must never set up and have enabled more than one transmit object with the same message ID arbitration field at the same time It is possible and likely that you will turn the AVT interface unit into a babbling idiot I won t go into the details here of why If you don t understand write or call me and ll explain Solution 1 e Handle both the keep alive and test messages in your application software e This will work but could be cumbersome and or difficult to implement Solution 2 A better method e Set up Typel Periodic Message 1 which uses object 1 as your keep alive message e Send your test messages out object 1 using the short form transmit command e The AVT 718 code will automatically prevent either mes
24. essage Object 6 is used here This example is not related to the previous demonstration All commands are shown Responses are in italics Set up the Global Message Masks as required Default status is recommended 11 bit mask 73 01 xx yy gt 8301 xx yy 29 bit mask 75 02 rr ss tt vv gt 85 02 rr ss tt vv Disable the object if necessary 73 040600 gt 83 04 06 00 Advanced Vehicle Technologies Inc Page 7 Set the object configuration 77 05 06 10 01 00 03 C4 gt 8705 06 10 01 03 03 C4 Explanation 77 05 Command upper nibble 7 byte count lower nibble 7 and command type 05 06 Object number 10 Transmit 01 Standard arbitration field 11 bits 00 Data length not used 03 C4 Arbitration field Enable the object 73040610 gt 83 0406 10 Set the object data to be transmitted 75 06 06 1A 2B 3C gt 85 06 06 IA 2B 3C Explanation 75 06 Header byte command and command type 06 Object number 1A 2B 3C Actual message data Transmit the message 73070601 gt 83070601 This response indicates that the command was executed only Notification that the message has been successfully transmitted Response 82 09 06 This response indicates the message was actually transmitted 8x 09 06 jj kk Il mm time stamp is appended to the end if enabled Time stamp is two or four bytes depending on model Short Form Transmit Command The AVT 418 and AVT 718 units firmware v
25. hnologies Inc Page 12 Response 82 28 00 No objects are paired 83 28 Ox Oy Objects Ox and Oy are paired ISO 15765 processing is enabled for the pair Address extension is disabled for the pair 84 28 Ox Oy ww Objects Ox and Oy are paired ISO 15765 processing is enabled for the pair Address extension is enabled for the pair If the address extension feature of ISO 15765 is used the user must specify the address extension byte for the flow control frames Our experience has shown that the majority of CAN networks using ISO 15765 do not use the address extension function However some GM LAN networks may use it 7x 26 Command The 7x 26 command is not recommended for new designs ISO 15765 Processing Command 71 26 ISO 15765 support status query 72 26 00 ISO 15765 support disabled Default 73 26 01 Ox ISO 15765 support enabled Normal addressing Flow control transmit object is Ox 01 to OE 74 26 02 Ox yy ISO 15765 support enabled Extended addressing Flow control transmit object is Ox 01 to OE Flow control address extension byte is yy Object Pairing When ISO 15765 processing is enabled using the 7x 26 command all receive messages are subjected to ISO 15765 processing There is only one transmit object associated with all the received messages This is not adequate when communicating with multiple modules using different message IDs There may also be instances where some network messages conform to IS
26. m nn message ID Ae optional address extension byte pp qq actual data bytes of the message e The AVT 418 718 handles all the necessary operations to properly receive the message from the network using ISO 15765 protocol Error Trapping The user is strongly recommended to include in their application software a means or method for trapping and preferably storing all error codes received from the AVT 418 718 unit All error messages from the AVT 418 718 are of the form 2X yy ZZ Examples 22 55 02 indicates that a received message had an incorrect PCI byte 25 55 36 xx yy zz indicates that a buffer timed out xx buffer number yy mode byte zz flag byte Advanced Vehicle Technologies Inc Page 20 A complete list of the error codes is provided below and in the Master Commands and Responses document Contact this office for clarification and explanation if error codes are received Summary Paired Mode version 5 9 and above e I5P is enabled disabled by object pair e AE is enabled disabled by object pair e Receive object uses paired transmit object to transmit flow control frame e Transmit object uses paired receive object to receive flow control frame e Specified AE byte is used only in transmitting a flow control frame e User must set up receive object e User must set up transmit object e Transmit short form command should be used Specified object number and ID must be consistent wi
27. ns Write or call for clarification and guidance The most up to date version of the Master Commands and Responses document is available for downloading from our web site at http www AVT HQ com download htm Notes Works Cited Intel 82527 Serial Communications Controller Architectural Overview Automotive Mt Prospect IL Intel Corp February 1995 Order number 272410 002 Advanced Vehicle Technologies Inc Page 16 2 February 2005 AVT 418 718 ISO 15765 Processing Notes Note I5P ISO 15765 processing CAN mode operations of AVT 418 718 firmware versions 5 1 to 5 8 had ISO 15765 processing I5P available There were several operational limitations to that function e The operator could only specify a single transmit object for flow control frames e All transmit and receive objects were enabled or disabled globally With increasingly complex applications it is necessary to e Be able to specify a transmit object for each receive object object pairing e Be able to enable or disable I5P processing for individual objects AVT 418 718 firmware versions 5 9 and above provide the capability to enable or disable I5P processing by object number and declare object pairs Statement ISO 15765 processing necessarily requires the declaration of object pairs Technically this is not true but the AVT interface does not have a priora information about the size of any message to or from the network It must b
28. rol the bit time or inversely the baud rate These are listed here with the allowable ranges of values Baud rate prescaler TSEG1 TSEG2 Advanced Vehicle Technologies Inc Page 5 A Demonstration Any two AVT CAN interface units can be set up connected together and used to become familiar with CAN network and AVT interface operations The following listing provides a step by step example of how to set up two units identically so that messages can be sent from one to the other Interface Unit Connections e Connect the CAN_H and CAN_L signals of both interface units together e Supply power to both interface units e A separate host computer may be used for each interface unit Otherwise connect the host computer to one interface unit set it up and then switch the host computer to the other interface unit Interface Unit Configuration Configure both interface units as described here All commands are hex digits All commands are shown Responses are in italics Explanations for each command are provided Always select the baud rate before selecting the physical layer This will usually prevent error messages from being generated and possibly prevent the generation of error conditions on the network gt FI A5 gt 9112 92 04 xx Reset the interface unit gt E199 gt 9110 821100 Enter CAN mode CAN mode response no physical layer selected gt 720A 03 gt 820A 03 250 kbps baud rate gt 721102
29. sage from being lost or corrupted Solution 2 Example 1 Fl A5 reset the interface unit 2 E199 switch to CAN mode 3 72 0A 04 125 kbps 4 721102 two wire CAN C 5 771801 10 01 00 07 44 Typel Periodic Message 1 setup 6 761901 68 6A FI 3F Typel Periodic Message 1 data 7 72 1E01 Typel timer interval 10 msec 8 74 1B 01 00 64 Typel Periodic Message 1 to 100 1000 msec 9 731A 0101 Typel Periodic Message 1 enabled The AVT unit will send the programmed message using object 1 once per second until reset or disabled Send your test messages using object 1 and the short form of the transmit command OB 01 07 44 01 02 03 04 05 06 0708 test message with dummy data of O1 08 Caution Do not use the 7x 06 and 7x 07 commands to send your test messages It will not work properly Advanced Vehicle Technologies Inc Page 11 ISO 15765 Processing ISO 15765 is a detailed standard for the formatting of the data field of a CAN message It permits the transmission of any length of data from 00 to 4095 bytes even though a CAN frame limits the data to 8 bytes It also permits the addition of an address extension byte ISO 15765 message format processing is for the most part independent of arbitration field length message ID baud rate or physical layer Messages that use the ISO 15765 messaging format may be referred to as Segmented Messages or Multi Frame Messages or by other names A
30. th setup e Transmit long form method bypasses I5P processing e Periodic messages transmitted by the AVT unit TypeO or Type1 are not I5P processed Pairing Command 71 28 72 28 Ox 73 28 Ox Oy 74 28 Ox Oy ww Object pairing status query Default is no objects are paired Disable ISO 15765 processing for object Ox and it s pair Declare objects Ox and Oy as paired Enable ISO 15765 processing for the pair Address extension is disabled for the pair Object order is not important Declare objects Ox and Oy as paired Enable ISO 15765 processing for the pair Enable address extension and use byte ww in flow control frame Pairing Command Responses 82 28 00 83 28 Ox Oy 84 28 Ox Oy ww Error codes 2x 55 No objects are paired Objects Ox and Oy are paired ISO 15765 processing is enabled for the pair Address extension is disabled for the pair Objects Ox and Oy are paired ISO 15765 processing is enabled for the pair Address extension is enabled for the pair ISO 15765 processing error Error code follows Receive mode buffer time out buffer number follows Receive mode PCI frame type error Receive mode PCI byte count greater than or equal to CFG byte count Receive mode first frame received no small buffers available Receive mode flow control frame transmit attempt time out Receive mode flow control frame data field too short Advanced Vehicle Technologies Inc
31. this time e All messages to be sent to the network must use the short form transmit command They will be processed formatted and transmitted on to the network according to ISO 15765 e Note The order of the commands The receive object is enabled last Advanced Vehicle Technologies Inc Page 18 Disable a receive message ID e Determine the receive object number Or e Disable the receive object 73 04 Or 00 strongly recommended e Disable the transmit object 73 04 Or 00 optional but recommended e Disable I5P for that object pair 72 28 Or Transmit a message onto the network e Depending on how many data bytes are to be transmitted there are three forms of the short form transmit command available e Include the address extension AE byte if used e Do not include the PCI byte e Do not include any pad bytes Use the short form transmit command Ox tt mm nn ae pp qq Ox count of number of bytes that follow tt transmit object to use mm nn message ID Ae optional address extension byte pp qq actual data bytes of the message gt or 11 xx tt mm nn ae pp qq XX count of number of bytes that follow tt transmit object to use mm nn message ID Ae optional address extension byte pp qq actual data bytes of the message gt or 12 Oy xx tt mm nn pp qq xxyy count of number of bytes that follow tt transmit object to use
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