Re: How CRC for CAN bus is calculated

@steve

Your code seems to be CRC-16 ?

>> Here's some example C code that calculates the CRC for a CAN message.
Does CAN controller does not do the CRC calculation of data message on its
own ?

Regards,
Dinesh


On Wed, Jan 8, 2014 at 6:52 PM, Stephen Glow <[email protected]
> wrote:

> Here's some example C code that calculates the CRC for a CAN message.
>
> Rgds,
> Steve
>
> static uint16_t CRC_AddBits( uint16_t crc, uint16_t value, int bct )
> {
>    uint16_t mask = 1<<(bct-1);
>    while( mask )
>    {
>       int bit = (value&mask) ? 1 : 0;
>       if( crc & 0x4000 )
>      bit = !bit;
>       crc <<= 1;
>       if( bit ) crc ^= 0x4599;
>       mask>>=1;
>    }
>
>    return crc & 0x7FFF;
> }
>
> static uint16_t CalcCRC( int id, int ct, uint8_t data[] )
> {
>    uint16_t crc = 0;
>    int i;
>
>    // Add start of frame and ID
>    crc = CRC_AddBits( crc, id&0x7FF, 12 );
>
>    // Add RTR, IDE, r1 and count
>    crc = CRC_AddBits( crc, ct&0x0F, 7 );
>
>    if( ct > 8 ) ct = 8;
>
>    for( i=0; i<ct; i++ )
>       crc = CRC_AddBits( crc, data[i], 8 );
>
>    return crc;
>
> }
>
>
> On 01/08/2014 08:03 AM, yogesh zambare wrote:
>
>> Dear All,
>> Can anybody tell me how CRC for CAN bus is calculated?
>>
>> Regards,
>> Yogesh Zambare
>> --
>> Archives and useful links: http://groups.yahoo.com/group/CANbus
>> Subscribe and unsubscribe at www.vector.com/canlist/
>> Report any problems to <[email protected]>
>>
>
> --
> Archives and useful links: http://groups.yahoo.com/group/CANbus
> Subscribe and unsubscribe at www.vector.com/canlist/
> Report any problems to <[email protected]>
>