MSP430F6659: Need help with CRC-16 calculation acc. to CCITT to communicate via TMS3705 to TMS37157

Part Number:MSP430F6659

Hello,

I'd like to calculate the CRC-16 acc. to CCITT to communicate via TMS3705 to TMS37157.

I have a working code just using shift operation.

I adopted this: https://en.wikipedia.org/wiki/Computation_of_cyclic_redundancy_checks, code fragment 5, shift register based division, LSB first and it works perfect.

The MSP430F6659 has a hardware CRC module and I'd like to use this, because it is the faster and more elegant solution.

This is the code I tested so far, but it didn't deliver the correct result in comparison to the software solution:

  unsigned int i, CRC_Result, CRC_Init = 0x3791;
  
  CRCRESR = CRC_Init;  // CRCINIRES = CRC_Init;
  for(i=0; i<length; i++)
  {
    CRCDIRB = string[i];
  }
  CRC_Result = CRCRESR;

  return(CRC_Result);

I try to use the reverse (see above) and the non reverse registers, but non of the version seem to work.

Please help

Kind regards

Gerd