CAN Library

The mikroBasic PRO for AVR provides a library (driver) for working with the CAN module.

The CAN is a very robust protocol that has error detection and signalization, self–checking and fault confinement. Faulty CAN data and remote frames are re-transmitted automatically, similar to the Ethernet.

Data transfer rates depend on distance. For example, 1 Mbit/s can be achieved at network lengths below 40m while 250 Kbit/s can be achieved at network lengths below 250m. The greater distance the lower maximum bitrate that can be achieved. The lowest bitrate defined by the standard is 200Kbit/s. Cables used are shielded twisted pairs.

CAN supports two message formats:

Standard format, with 11 identifier bits, and
Extended format, with 29 identifier bits.

Important :

CAN library routines are supported for these devices : AT90CAN32, AT90CAN64, AT90CAN128, ATMEGA16M1, ATMEGA32M1 and ATMEGA64M1.
Microcontroller must be connected to CAN transceiver (MCP2551 or similar) which is connected to CAN bus.
Consult the CAN standard about CAN bus termination resistance.

CANSetOperationMode

Prototype	sub procedure CANSetOperationMode(dim mode, wait_flag as byte)
Returns	Nothing.
Description	Sets CAN to requested mode, i.e. copies `mode` to CANSTAT. Parameter `mode` needs to be one of `CAN_OP_MODE` constants (see CAN constants). Parameter `wait_flag` needs to be either 0 or 0xFF: If set to 0xFF, this is a blocking call – the function won’t “return” until the requested mode is set. If 0, this is a non-blocking call. It does not verify if CAN module is switched to requested mode or not. Caller must use `CANGetOperationMode` to verify correct operation mode before performing mode specific operation.
Requires	CAN routines are currently supported only by AT90CANXXX and ATMEGAXXM1 MCUs. Microcontroller must be connected to CAN transceiver (MCP2551 or similar) which is connected to CAN bus.
Example	CANSetOperationMode(_CAN_MODE_CONFIG, $FF)

CANGetOperationMode

Prototype	sub function CANGetOperationMode() as byte
Returns	Current opmode.
Description	Function returns current operational mode of CAN module.
Requires	CAN routines are currently supported only by AT90CANXXX and ATMEGAXXM1 MCUs. Microcontroller must be connected to CAN transceiver (MCP2551 or similar) which is connected to CAN bus.
Example	if CANGetOperationMode() = _CAN_MODE_NORMAL then ...

CANInitialize

Prototype	sub procedure CANInitialize(dim SJW, BRP, PHSEG1, PHSEG2, PROPSEG, CAN_CONFIG_FLAGS as byte)
Returns	Nothing.
Description	Initializes CAN. All pending transmissions are aborted. Sets all mask registers to 0 to allow all messages. The Config mode is internaly set by this function. Upon a execution of this function Normal mode is set. Filter registers are set according to flag value: if (CAN_CONFIG_FLAGS and _CAN_CONFIG_XTD_MSG) <> 0 ' Set all filters to XTD_MSG else if (config and _CAN_CONFIG_STD_MSG) <> 0 ' Set all filters to STD_MSG else ' Set half of the filters to STD, and the rest to XTD_MSG. Parameters: `SJW` as defined in MCU's datasheet `BRP` as defined in MCU's datasheet `PHSEG1` as defined in MCU's datasheet `PHSEG2` as defined in MCU's datasheet `PROPSEG` as defined in MCU's datasheet `CAN_CONFIG_FLAGS` is formed from predefined constants (see CAN constants)
Requires	CAN must be in Config mode; otherwise the function will be ignored. Microcontroller must be connected to CAN transceiver (MCP2551 or similar) which is connected to CAN bus.
Example	init = _CAN_CONFIG_SAMPLE_THRICE and _CAN_CONFIG_MSG_TYPE_BIT and _CAN_CONFIG_STD_MSG ... CANInitialize(1, 1, 3, 3, 1, init) ' Initialize CAN

CANSetBaudRate

Prototype	sub procedure CANSetBaudRate(dim SJW, BRP, PHSEG1, PHSEG2, PROPSEG, CAN_CONFIG_FLAGS as byte)
Returns	Nothing.
Description	Sets CAN baud rate. Due to complexity of CAN protocol, you cannot simply force a bps value. Instead, use this function when CAN is in Config mode. Refer to datasheet for details. Parameters: `SJW` as defined in MCU's datasheet `BRP` as defined in MCU's datasheet `PHSEG1` as defined in MCU's datasheet `PHSEG2` as defined in MCU's datasheet `PROPSEG` as defined in MCU's datasheet `CAN_CONFIG_FLAGS` is formed from predefined constants (see CAN constants)
Requires	CAN must be in Config mode; otherwise the function will be ignored. CAN routines are currently supported only by AT90CANXXX and ATMEGAXXM1 MCUs. Microcontroller must be connected to CAN transceiver (MCP2551 or similar) which is connected to CAN bus.
Example	init = _CAN_CONFIG_SAMPLE_THRICE and _CAN_CONFIG_MSG_TYPE_BIT and _CAN_CONFIG_STD_MSG ... CANSetBaudRate(1, 1, 3, 3, 1, init)

CANSetMask

Prototype	sub procedure CANSetMask(dim CAN_MASK as byte, dim value as longint, dim CAN_CONFIG_FLAGS as byte)
Returns	Nothing.
Description	Function sets mask for advanced filtering of messages. Given `value` is bit adjusted to appropriate buffer mask registers. Parameters: `CAN_MASK` is one of predefined constant values (see CAN constants) `value` is the mask register value `CAN_CONFIG_FLAGS` selects type of message to filter, either `_CAN_CONFIG_XTD_MSG` or `_CAN_CONFIG_STD_MSG`
Requires	CAN must be in Config mode; otherwise the function will be ignored. CAN routines are currently supported only by AT90CANXXX and ATMEGAXXM1 MCUs. Microcontroller must be connected to CAN transceiver (MCP2551 or similar) which is connected to CAN bus.
Example	' Set all mask bits to 1, i.e. all filtered bits are relevant: CANSetMask(_CAN_MASK_B1, -1, _CAN_CONFIG_XTD_MSG) ' Note that -1 is just a cheaper way to write 0xFFFFFFFF. ' Complement will do the trick and fill it up with ones.

CANSetFilter

Prototype	sub procedure CANSetFilter(dim CAN_FILTER as byte, dim value as longint, dim CAN_CONFIG_FLAGS as byte)
Returns	Nothing.
Description	Function sets message filter. Given `value` is bit adjusted to appropriate buffer mask registers. Parameters: `CAN_FILTER` is one of predefined constant values (see CAN constants) `value` is the filter register value `CAN_CONFIG_FLAGS` selects type of message to filter, either `_CAN_CONFIG_XTD_MSG` or `_CAN_CONFIG_STD_MSG`
Requires	CAN must be in Config mode; otherwise the function will be ignored. CAN routines are currently supported only by AT90CANXXX and ATMEGAXXM1 MCUs. Microcontroller must be connected to CAN transceiver (MCP2551 or similar) which is connected to CAN bus.
Example	' Set id of filter F1 to 3: CANSetFilter(CAN_RX_FILTER_1, 3, _CAN_CONFIG_XTD_MSG)

CANRead

Prototype	sub function CANRead(dim byref id as longint, dim byref data as byte[8], dim byref datalen, CAN_RX_MSG_FLAGS as byte) as byte
Returns	Message from receive buffer or zero if no message found.
Description	Function reads message from receive buffer. If at least one full receive buffer is found, it is extracted and returned. If none found, function returns zero. Parameters: `id` is message identifier `data` is an array of bytes up to 8 bytes in length `datalen` is data length, from 1–8. `CAN_RX_MSG_FLAGS` is value formed from constants (see CAN constants)
Requires	CAN must be in mode in which receiving is possible. CAN routines are currently supported only by AT90CANXXX and ATMEGAXXM1 MCUs. Microcontroller must be connected to CAN transceiver (MCP2551 or similar) which is connected to CAN bus.
Example	dim len, rcv, rx as byte dim id as longint dim data as byte[8] ' ... rx = 0 ' ... rcv = CANRead(id, data, len, rx)

CANWrite

Prototype	sub function CANWrite(dim id as longint, dim byref data as byte[8], dim datalen, CAN_TX_MSG_FLAGS as byte) as byte
Returns	Returns zero if message cannot be queued (buffer full).
Description	If at least one empty transmit buffer is found, function sends message on queue for transmission. If buffer is full, function returns 0. Parameters: `id` is CAN message identifier. Only 11 or 29 bits may be used depending on message type (standard or extended) `data` is array of bytes up to 8 bytes in length `datalen` is data length from 1–8 `CAN_TX_MSG_FLAGS` is value formed from constants (see CAN constants)
Requires	CAN must be in Normal mode. CAN routines are currently supported only by AT90CANXXX and ATMEGAXXM1 MCUs. Microcontroller must be connected to CAN transceiver (MCP2551 or similar) which is connected to CAN bus.
Example	dim id as longint dim tx, data as byte ' ... tx = _CAN_TX_PRIORITY_0 and _CAN_TX_XTD_FRAME ' ... CANWrite(id, data, 2, tx)

CAN Constants

There is a number of constants predefined in CAN library. To be able to use the library effectively, you need to be familiar with these. You might want to check the example at the end of the chapter.

CAN_OP_MODE

CAN_OP_MODE constants define CAN operation mode. Function CANSetOperationMode expects one of these as its argument:

const _CAN_MODE_BITS    = 0x0A   ' Use this to access opmode  bits
const _CAN_MODE_STANDBY = 0x00
const _CAN_MODE_ENABLE  = 0x02
const _CAN_MODE_LISTEN  = 0x08

CAN_CONFIG_FLAGS

CAN_CONFIG_FLAGS constants define flags related to CAN module configuration. Functions CANInitialize and CANSetBaudRate expect one of these (or a bitwise combination) as their argument:

const _CAN_CONFIG_SAMPLE_BIT      = 0x01
const _CAN_CONFIG_SAMPLE_ONCE     = 0xFE   ' XXXX XXX0
const _CAN_CONFIG_SAMPLE_THRICE   = 0xFF   ' XXXX XXX1

const _CAN_CONFIG_MSG_TYPE_BIT    = 0x10
const _CAN_CONFIG_STD_MSG         = 0xEF   ' XXX0 XXXX
const _CAN_CONFIG_XTD_MSG         = 0xFF   ' XXX1 XXXX

You may use bitwise and to form config byte out of these values. For example:

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init =  _CAN_CONFIG_SAMPLE_THRICE and
        _CAN_CONFIG_STD_MSG

...
CANInitialize(1, 1, 3, 3, 1, init)   ' Initialize CAN

CAN_TX_MSG_FLAGS

CAN_TX_MSG_FLAGS are flags related to transmission of a CAN message:

const _CAN_CONMOB_DIS        = 0x3F   ' 00XX XXXX   messsage objects work modes
const _CAN_CONMOB_EN_TX      = 0x7F   ' 01XX XXXX
const _CAN_CONMOB_EN_RX      = 0xBF   ' 10XX XXXX
const _CAN_CONMOB_EN_FRAME   = 0xFF   ' 11XX XXXX

const _CAN_IDE_FRAME_BIT     = 0x10   ' Identifier Extension
const _CAN_IDE_STD_FRAME     = 0xEF   ' XXX0 XXXX
const _CAN_IDE_XTD_FRAME     = 0xFF   ' XXX1 XXXX

const _CAN_RTR_BIT           = 0x20
const _CAN_NO_RTR_FRAME      = 0xFF   ' XX1XXXXX
const _CAN_RTR_FRAME         = 0xDF   ' XX0XXXXX

const _CAN_TX                = 0x01   ' Transmitter Busy
const _CAN_TX_NO_BSY         = 0xFE   ' XXXX XXX0
const _CAN_TX_BSY            = 0xFF   ' XXXX XXX1

You may use bitwise and to adjust the appropriate flags. For example:

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' form value to be used with CANSendMessage:
send_config =  _CAN_TX_PRIORITY_0 and
               _CAN_TX_XTD_FRAME  and
               _CAN_TX_NO_RTR_FRAME
...
CANWrite(id, data, 1, send_config)

CAN_RX_MSG_FLAGS

CAN_RX_MSG_FLAGS are flags related to reception of CAN message. If a particular bit is set; corresponding meaning is TRUE or else it will be FALSE.

const _CAN_RX        = 0x08   ' Receiver Busy
const _CAN_RX_NO_BSY = 0xF7   ' XXXX 0XXX
const _CAN_RX_BSY    = 0xFF   ' XXXX 1XXX

You may use bitwise and to adjust the appropriate flags. For example:

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if (MsgFlag and _CAN_RX_BSY) = 0 then
  ...
  ' Receiver is busy.

CAN_MASK

CAN_MASK constants define mask codes. Function CANSetMask expects one of these as its argument:

const CAN_RX_MASK_0  = 0x00
const CAN_RX_MASK_1  = 0x01
const CAN_RX_MASK_2  = 0x02
const CAN_RX_MASK_3  = 0x03
const CAN_RX_MASK_4  = 0x04
const CAN_RX_MASK_5  = 0x05
const CAN_RX_MASK_6  = 0x06
const CAN_RX_MASK_7  = 0x07
const CAN_RX_MASK_8  = 0x08
const CAN_RX_MASK_9  = 0x09
const CAN_RX_MASK_10 = 0x0A
const CAN_RX_MASK_11 = 0x0B
const CAN_RX_MASK_12 = 0x0C
const CAN_RX_MASK_13 = 0x0D
const CAN_RX_MASK_14 = 0x0E

CAN_FILTER

CAN_FILTER constants define filter codes. Function CANSetFilter expects one of these as its argument:

const CAN_RX_FILTER_0  = 0x00
const CAN_RX_FILTER_1  = 0x01
const CAN_RX_FILTER_2  = 0x02
const CAN_RX_FILTER_3  = 0x03
const CAN_RX_FILTER_4  = 0x04
const CAN_RX_FILTER_5  = 0x05
const CAN_RX_FILTER_6  = 0x06
const CAN_RX_FILTER_7  = 0x07
const CAN_RX_FILTER_8  = 0x08
const CAN_RX_FILTER_9  = 0x09
const CAN_RX_FILTER_10 = 0x0A
const CAN_RX_FILTER_11 = 0x0B
const CAN_RX_FILTER_12 = 0x0C
const CAN_RX_FILTER_13 = 0x0D
const CAN_RX_FILTER_14 = 0x0E

CAN_MOB

CAN_MOB constants define flags related to transmission of a CAN message :


const _CAN_EN_MOB0_BIT    = 0x0001 ' Flags, set to 1 if the appropriate MOb is in use. When the appropriate operation ends, TXOK or RXOK are set to 1
const _CAN_EN_MOB1_BIT    = 0x0002
const _CAN_EN_MOB2_BIT    = 0x0004
const _CAN_EN_MOB3_BIT    = 0x0008
const _CAN_EN_MOB4_BIT    = 0x0010
const _CAN_EN_MOB5_BIT    = 0x0020
const _CAN_EN_MOB6_BIT    = 0x0040
const _CAN_EN_MOB7_BIT    = 0x0080
const _CAN_EN_MOB8_BIT    = 0x0100
const _CAN_EN_MOB9_BIT    = 0x0200
const _CAN_EN_MOB10_BIT   = 0x0400
const _CAN_EN_MOB11_BIT   = 0x0800
const _CAN_EN_MOB12_BIT   = 0x1000
const _CAN_EN_MOB13_BIT   = 0x2000
const _CAN_EN_MOB14_BIT   = 0x4000

const _CAN_CONFIG_STMOB_TXOK  = 0x40   ' X1XX XXXX  From the CAN MOb Status Register
const _CAN_CONFIG_STMOB_RXOK  = 0x20   ' XX1X XXXX  Receive OK
const _CAN_CONFIG_STMOB_BERR  = 0x10   ' XXX1 XXXX  Bit Error (Only in transmission)
const _CAN_CONFIG_STMOB_SERR  = 0x08   ' XXXX 1XXX  Stuff Error
const _CAN_CONFIG_STMOB_CERR  = 0x04   ' XXXX X1XX  CRC Error
const _CAN_CONFIG_STMOB_FERR  = 0x02   ' XXXX XX1X  Form Error
const _CAN_CONFIG_STMOB_AERR  = 0x01   ' XXXX XXX1  Acknowledgment Error

Library Example

This is a simple demonstration of CAN Library routines usage. First node initiates the communication with the second node by sending some data to its address. The second node responds by sending back the data incremented by 1. First node then does the same and sends incremented data back to second node, etc.

Code for the first CAN node:

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program CAN_1st

dim Can_Init_Flags, Can_Send_Flags, Can_Rcv_Flags as byte  ' can flags
    Rx_Data_Len as byte                             ' received data length in bytes
    RxTx_Data as byte[8]                            ' can rx/tx data buffer
    Msg_Rcvd as byte                                ' reception flag
    ID_1st, ID_2nd as longint                       ' node IDs
    Rx_ID as longint

main:
  PORTC = 0x00                                                ' clear PORTC
  DDRC  = 0xFF                                                ' set PORTC as output

  Msg_Rcvd = 0

  Can_Init_Flags = 0                                          '
  Can_Send_Flags = 0                                          ' clear flags
  Can_Rcv_Flags  = 0                                          '

  Can_Send_Flags = _CAN_IDE_XTD_FRAME                         ' form value to be used
                 and _CAN_NO_RTR_FRAME                        ' with CANWrite

  Can_Init_Flags = _CAN_CONFIG_SAMPLE_THRICE                  ' form value to be used
                 and _CAN_CONFIG_XTD_MSG                      ' with CANInit

  ID_1st = 12111
  ID_2nd = 3
  RxTx_Data[0] = 9

  CANInitialize(1,6,3,3,1,Can_Init_Flags)                     ' initialize external CAN module
  CANSetOperationMode(_CAN_MODE_STANDBY,0xFF)                 ' set STANDBY mode


  '-----------------------------------------------------------'
  CANSetFilter(CAN_RX_FILTER_3,  -1, _CAN_CONFIG_XTD_MSG)     '
  CANSetFilter(CAN_RX_FILTER_4, ID_2nd, _CAN_CONFIG_XTD_MSG)  ' set ID filter of 4th filter to 2nd node ID
  CANSetFilter(CAN_RX_FILTER_5,  -1, _CAN_CONFIG_XTD_MSG)     ' and ones to other filters
  CANSetFilter(CAN_RX_FILTER_6,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_7,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_8,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_9,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_10, -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_11, -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_12, -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_13, -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_14, -1, _CAN_CONFIG_XTD_MSG)
  '-----------------------------------------------------------'

  ' set all mask bits of masks[3..14] to all ones
  '-----------------------------------------------------------'
  CANSetMask(CAN_RX_MASK_3,  -1, _CAN_CONFIG_XTD_MSG)         ' set all mask bits of masks[3..14] to all ones
  CANSetMask(CAN_RX_MASK_4,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_5,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_6,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_7,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_8,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_9,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_10, -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_11, -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_12, -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_13, -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_14, -1, _CAN_CONFIG_XTD_MSG)
  '-----------------------------------------------------------'

  CANSetOperationMode(_CAN_MODE_ENABLE,0xFF)                                    ' set ENABLE mode

  RxTx_Data[0] = 9                                                              ' set initial data to be sent
  CANWrite(ID_1st, RxTx_Data, 1, Can_Send_Flags)                                ' send initial message

  while TRUE
      Msg_Rcvd = CANRead(Rx_ID , RxTx_Data , Rx_Data_Len, Can_Rcv_Flags)
      if ((Rx_ID = ID_2nd) and (Msg_Rcvd <> 0)) <> 0 then
          PORTC = RxTx_Data[0]                                                  ' output data at PORTC
          RxTx_Data[0] = RxTx_Data[0] + 1
          Delay_ms(10)
          CANWrite(ID_1st, RxTx_Data, 1, Can_Send_Flags)                        ' send incremented data back
      end if
  wend
end.

Code for the second CAN node:

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program CAN_2nd

dim Can_Init_Flags, Can_Send_Flags, Can_Rcv_Flags as byte  ' can flags
    Rx_Data_Len as byte                             ' received data length in bytes
    RxTx_Data as byte[8]                            ' can rx/tx data buffer
    Msg_Rcvd as byte                                ' reception flag
    ID_1st, ID_2nd as longint                       ' node IDs
    Rx_ID as longint

main:
  PORTC = 0x00                                                ' clear PORTC
  DDRC  = 0xFF                                                ' set PORTC as output

  Msg_Rcvd = 0

  Can_Init_Flags = 0                                          '
  Can_Send_Flags = 0                                          ' clear flags
  Can_Rcv_Flags  = 0                                          '

  Can_Send_Flags = _CAN_IDE_XTD_FRAME                         ' form value to be used
                 and _CAN_NO_RTR_FRAME                        ' with CANWrite

  Can_Init_Flags = _CAN_CONFIG_SAMPLE_THRICE                  ' form value to be used
                 and _CAN_CONFIG_XTD_MSG                      ' with CANInit

  ID_1st = 12111
  ID_2nd = 3
  RxTx_Data[0] = 9

  CANInitialize(1,6,3,3,1,Can_Init_Flags)                     ' initialize external CAN module
  CANSetOperationMode(_CAN_MODE_STANDBY,0xFF)                 ' set STANDBY mode


  '-----------------------------------------------------------'
  CANSetFilter(CAN_RX_FILTER_3,  -1, _CAN_CONFIG_XTD_MSG)     '
  CANSetFilter(CAN_RX_FILTER_4, ID_2nd, _CAN_CONFIG_XTD_MSG)  ' set ID filter of 4th filter to 2nd node ID
  CANSetFilter(CAN_RX_FILTER_5,  -1, _CAN_CONFIG_XTD_MSG)     ' and ones to other filters
  CANSetFilter(CAN_RX_FILTER_6,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_7,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_8,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_9,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_10, -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_11, -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_12, -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_13, -1, _CAN_CONFIG_XTD_MSG)
  CANSetFilter(CAN_RX_FILTER_14, -1, _CAN_CONFIG_XTD_MSG)
  '-----------------------------------------------------------'

  ' set all mask bits of masks[3..14] to all ones
  '-----------------------------------------------------------'
  CANSetMask(CAN_RX_MASK_3,  -1, _CAN_CONFIG_XTD_MSG)         ' set all mask bits of masks[3..14] to all ones
  CANSetMask(CAN_RX_MASK_4,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_5,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_6,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_7,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_8,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_9,  -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_10, -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_11, -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_12, -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_13, -1, _CAN_CONFIG_XTD_MSG)
  CANSetMask(CAN_RX_MASK_14, -1, _CAN_CONFIG_XTD_MSG)
  '-----------------------------------------------------------'

  CANSetOperationMode(_CAN_MODE_ENABLE,0xFF)                                    ' set ENABLE mode

  while true                                                             ' endless loop
    Msg_Rcvd = CANRead(Rx_ID , RxTx_Data , Rx_Data_Len, Can_Rcv_Flags)   ' receive message
    if ((Rx_ID = ID_1st) and (Msg_Rcvd <> 0)) <> 0 then                  ' if message received check id
      PORTC = RxTx_Data[0]                                               ' id correct, output data at PORTC
      Inc(RxTx_Data[0])                                                  ' increment received data
      CANWrite(ID_2nd, RxTx_Data, 1, Can_Send_Flags)                     ' send incremented data back
    end if
  wend
end.

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