Connect CAN-SPI with PIC Controller

• mode: CANSPI module operation mode. Valid values: CANSPI_OP_MODE constants.
• WAIT: CANSPI mode switching verification request. If WAIT == 0, the call is non-blocking. The function does not verify if the CANSPI module is switched to requested mode or not. Caller must use CANSPIGetOperationMode to verify correct operation mode before performing mode specific operation. If WAIT != 0, the call is blocking – the function won’t “return” until the requested mode is set.

// set the CANSPI module into configuration mode (wait inside CANSPISetOperationMode until this mode is set)
CANSPISetOperationMode(_CANSPI_MODE_CONFIG, 0xFF);

// check whether the CANSPI module is in Normal mode and if it is do something.
if (CANSPIGetOperationMode() == _CANSPI_MODE_NORMAL) {
  ...
}

• Disable CAN capture
• Continue CAN operation in Idle mode
• Do not abort pending transmissions
• Fcan clock : 4*Tcy (Fosc)
• Baud rate is set according to given parameters
• CAN mode : Normal
• Filter and mask registers IDs are set to zero
• Filter and mask message frame type is set according to CANSPI_CONFIG_FLAGS value

SAM, SEG2PHTS, WAKFIL and DBEN bits are set according to CANSPI_CONFIG_FLAGS value.
Parameters:

• SJW as defined in CAN controller’s datasheet
• BRP as defined in CAN controller’s datasheet
• PHSEG1 as defined in CAN controller’s datasheet
• PHSEG2 as defined in CAN controller’s datasheet
• PROPSEG as defined in CAN controller’s datasheet
• CANSPI_CONFIG_FLAGS is formed from predefined constants

• CanSpi_CS: Chip Select line
• CanSpi_Rst: Reset line
• CanSpi_CS_Direction: Direction of the Chip Select pin
• CanSpi_Rst_Direction: Direction of the Reset pin

must be defined before using this function.
The CANSPI routines are supported only by MCUs with the SPI module.
The SPI module needs to be initialized. See the SPIx_Init and SPIx_Init_Advanced routines.
MCU has to be properly connected to mikroElektronika’s CANSPI Extra Board or similar hardware. See connection example at the bottom of this page.

// CANSPI module connections
sbit CanSpi_CS  at  RC0_bit;
sbit CanSpi_CS_Direction  at  TRISC0_bit;
sbit CanSpi_Rst at  RC2_bit;
sbit CanSpi_Rst_Direction at  TRISC2_bit;
// End CANSPI module connections

// initialize the CANSPI module with the appropriate baud rate and message acceptance flags along with the sampling rules
char CanSPi_Init_Flags;
  ...  
  CanSPi_Init_Flags = _CANSPI_CONFIG_SAMPLE_THRICE &  // form value to be used
                   _CANSPI_CONFIG_PHSEG2_PRG_ON &  // with CANSPIInitialize
                   _CANSPI_CONFIG_XTD_MSG &
                   _CANSPI_CONFIG_DBL_BUFFER_ON &
                   _CANSPI_CONFIG_VALID_XTD_MSG;
  ...
  SPI1_Init();                                // initialize SPI module
  CANSPIInitialize(1,3,3,3,1,CanSpi_Init_Flags);  // initialize external CANSPI module

• SJW as defined in CAN controller’s datasheet
• BRP as defined in CAN controller’s datasheet
• PHSEG1 as defined in CAN controller’s datasheet
• PHSEG2 as defined in CAN controller’s datasheet
• PROPSEG as defined in CAN controller’s datasheet
• CANSPI_CONFIG_FLAGS is formed from predefined constants

// set required baud rate and sampling rules
char canspi_config_flags;
...  
CANSPISetOperationMode(CANSPI_MODE_CONFIG,0xFF);              // set CONFIGURATION mode (CANSPI module mast be in config mode for baud rate settings)
canspi_config_flags = _CANSPI_CONFIG_SAMPLE_THRICE &
                   _CANSPI_CONFIG_PHSEG2_PRG_ON &
                   _CANSPI_CONFIG_STD_MSG       &
                   _CANSPI_CONFIG_DBL_BUFFER_ON &
                   _CANSPI_CONFIG_VALID_XTD_MSG &
                   _CANSPI_CONFIG_LINE_FILTER_OFF;
CANSPISetBaudRate(1, 1, 3, 3, 1, canspi_config_flags);

• CANSPI_MASK: CANSPI module mask number. Valid values: CANSPI_MASK constants (see CANSPI constants)
• val: mask register value
• CANSPI_CONFIG_FLAGS: selects type of message to filter. Valid values:
  • _CANSPI_CONFIG_ALL_VALID_MSG,
  • _CANSPI_CONFIG_MATCH_MSG_TYPE & _CANSPI_CONFIG_STD_MSG,
  • _CANSPI_CONFIG_MATCH_MSG_TYPE & _CANSPI_CONFIG_XTD_MSG.

// set the appropriate filter mask and message type value
CANSPISetOperationMode(_CANSPI_MODE_CONFIG,0xFF);              // set CONFIGURATION mode (CANSPI module must be in config mode for mask settings)

// Set all B1 mask bits to 1 (all filtered bits are relevant):
// Note that -1 is just a cheaper way to write 0xFFFFFFFF.
// Complement will do the trick and fill it up with ones.
CANSPISetMask(_CANSPI_MASK_B1, -1, _CANSPI_CONFIG_MATCH_MSG_TYPE & _CANSPI_CONFIG_XTD_MSG);

• CANSPI_FILTER: CANSPI module filter number. Valid values: CANSPI_FILTER constants
• val: filter register value
• CANSPI_CONFIG_FLAGS: selects type of message to filter. Valid values:
  • _CANSPI_CONFIG_ALL_VALID_MSG,
  • _CANSPI_CONFIG_MATCH_MSG_TYPE & _CANSPI_CONFIG_STD_MSG,
  • _CANSPI_CONFIG_MATCH_MSG_TYPE & _CANSPI_CONFIG_XTD_MSG.

// set the appropriate filter value and message type
CANSPISetOperationMode(_CANSPI_MODE_CONFIG,0xFF);                  // set CONFIGURATION mode (CANSPI module must be in config mode for filter settings)

/* Set id of filter B1_F1 to 3: */
CANSPISetFilter(_CANSPI_FILTER_B1_F1, 3, _CANSPI_CONFIG_XTD_MSG);

• 0 if nothing is received
• 0xFF if one of the Receive Buffers is full (message received)

• Message ID is retrieved and stored to location provided by the id parameter
• Message data is retrieved and stored to a buffer provided by the rd_data parameter
• Message length is retrieved and stored to location provided by the data_len parameter
• Message flags are retrieved and stored to location provided by the CANSPI_RX_MSG_FLAGS parameter

Parameters:

• id: message identifier storage address
• rd_data: data buffer (an array of bytes up to 8 bytes in length)
• data_len: data length storage address.
• CANSPI_RX_MSG_FLAGS: message flags storage address

// check the CANSPI module for received messages. If any was received do something. 
char msg_rcvd, rx_flags, data_len;
char data[8];
long msg_id;
...
CANSPISetOperationMode(_CANSPI_MODE_NORMAL,0xFF);                  // set NORMAL mode (CANSPI module must be in mode in which receive is possible)
...
rx_flags = 0;                                                // clear message flags
if (msg_rcvd = CANSPIRead(msg_id, data, data_len, rx_flags)) {
  ...
}

• 0 if all Transmit Buffers are busy
• 0xFF if at least one Transmit Buffer is available

• id:CAN message identifier. Valid values: 11 or 29 bit values, depending on message type (standard or extended)
• wr_data: data to be sent (an array of bytes up to 8 bytes in length)
• data_len: data length. Valid values: 1 to 8
• CANSPI_RX_MSG_FLAGS: message flags

// send message extended CAN message with the appropriate ID and data
char tx_flags;
char data[8];
long msg_id;
...
CANSPISetOperationMode(_CANSPI_MODE_NORMAL,0xFF);                  // set NORMAL mode (CANSPI must be in mode in which transmission is possible)

tx_flags = _CANSPI_TX_PRIORITY_0 & _CANSPI_TX_XTD_FRAME;             // set message flags
CANSPIWrite(msg_id, data, 2, tx_flags);