38.2.2 Configuration Mode

After Reset, the CAN Protocol Module is in Configuration mode. The error counters are cleared and all registers contain the Reset values.

The CAN Protocol Module must be initialized before activation. This is only possible when the module is in Configuration mode, OPMOD[2:0] = 100. The Configuration mode is requested by setting REQOP[2:0] = 100.

The CAN Protocol module will protect the user from accidentally violating the CAN protocol through programming errors. The following registers and bit fields can only be programmed during Configuration mode:

  • CxCON: WAKFIL, CLKSEL, PXEDIS, ISOCRECEN, TXQEN, STEF, SERRLOM, ESIGM, RTXAT
  • CxNBTCFG, C1DBTCFG and C1TDC
  • CxTXQCON: PLSIZE[2:0], FSIZE[4:0]
  • CxFIFOCON: TXEN, RXTSEN, PLSIZE[2:0], FSIZE[4:0]
  • CxTEFCON: TEFTSEN, FSIZE[4:0]
  • CxFIFOBA

The CAN Protocol module is not allowed to enter Configuration mode during transmission or reception to prevent the module from causing errors on the CAN bus. The following registers are Reset when exiting Configuration mode:

  • CxTREC
  • CxBDIAG0
  • CxBDIAG1

In Configuration mode, FRESET is set in the CxFIFOCON, CxTXQCON, and CxTEFCON registers, and all FIFOs and the TXQ are Reset.