TMS320F280039C: VCRC configuration to match standard crc-32 algorithm

Kevin Lannen

Part Number: TMS320F280039C
Other Parts Discussed in Thread: C2000WARE

Hi,

I am trying to configure the VCRC to produce an output equivalent to this calculator for a CRC-32 algorithm: https://crccalc.com/?crc=12&method=CRC-32&datatype=ascii&outtype=0

I have followed the 28003x_vcrc_crc_32 example from C2000Ware and came up with the following code:

    uint16_t buffer[1] = {0x3132};

    uint32_t crcResult = 0;

    txCrcHandle->seedValue = 0xFFFFFFFF;
    txCrcHandle->nMsgBytes = 2;
    txCrcHandle->parity = CRC_parity_even;
    txCrcHandle->crcResult = 0;
    txCrcHandle->pMsgBuffer = (uint16_t *)&buffer[0];
    txCrcHandle->init = CRC_init32Bit;
    txCrcHandle->run = CRC_run32BitPoly1;

    txCrcHandle->init(txCrcHandle);
    txCrcHandle->run(txCrcHandle);

    crcResult = txCrcHandle->crcResult;

which when run produces a result of 0x40442760. This does not match the result from the link above (0x4F5344CD).

I have tried several other settings and none of them will get the result to line up with the online calculators.

Any suggestions for what settings need changed would be appreciated.

Thanks,

Kevin

over 1 year ago

+1 Sira Rao80 over 1 year ago

TI__Mastermind 25940 points

The following should help you:

https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/1260124/tms320f280025-incorrect-output-using-the-crc-routine-provided-on-page-642-of-spruhs1c

We did some analysis on the differences between a CRC-32 and CRC32-MPEG2 implementation, and this analysis is captured in the picture below. The flipInputBuf_cpu() is an explicit C function needed in the case of VCU0, but in the VCRC, the input bits can be reversed using the VSETCRCMSGFLIP instruction.

Thanks,

Sira

0 Kevin Lannen over 1 year ago in reply to Sira Rao80

Intellectual 370 points

Hi Sira,

Thanks for the help! This gave me what I needed to get this working and I was able to match the output from https://crccalc.com/?crc=31 32&method=crc32&datatype=hex&outtype=0

For anyone else who finds this post, here's the final code I used to get this working:

    // Note: The CRC is fed the data from LSB to MSB so 0x31 is processed before 0x32.
    uint16_t buffer[1] = {0x3231};


    txCrcHandle->seedValue = 0xFFFFFFFF;
    txCrcHandle->nMsgBytes = 2;
    txCrcHandle->parity = CRC_parity_even;
    txCrcHandle->crcResult = 0x00000000;
    txCrcHandle->pMsgBuffer = (uint16_t *)&buffer[0];
    txCrcHandle->init = CRC_init32Bit;
    txCrcHandle->run = CRC_run32BitPoly1Reflected;

    txCrcHandle->init(txCrcHandle);
    txCrcHandle->run(txCrcHandle);

    crcResult = txCrcHandle->crcResult;

    crcResult = __flip32(crcResult);
    crcResult = ~crcResult;

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TMS320F280039C: VCRC configuration to match standard crc-32 algorithm