14.5.2 Configuration Mode

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

The CAN FD Protocol has to 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 FD Protocol 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, ISOCRCEN, TXQEN, STEF, SERR2LOM, ESIGM, RTXAT
  • CxNBTCFG, CxDBTCFG, CxTDC
  • CxTXQCON: PLSIZE[2:0], FSIZE[4:0], TXEN, RXTSEN
  • CxFIFOCONx: PLSIZE[2:0], FSIZE[4:0], TEFTSEN
  • CxTEFCON: FSIZE[4:0]
  • CxFIFOBA

The CAN FD Protocol 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 CxFIFOCONx, CxTXQCON and CxTEFCON registers, and all FIFOs and the TXQ are reset.