16-bit CRC using generate_16bit_crc()

MCU Luüfter · Joined: 13 Jun 2011 Posts: 6

Hi all,

I am using the 16-bit CRC available in \PICC\Drivers\
and I need your experience.
In fact I am checking the result of CRC usign the following online tool:

http://depa.usst.edu.cn/chenjq/www2/software/crc/CRC_Javascript/CRCcalculation.htm

and my code is:

MCU Luüfter · Joined: 13 Jun 2011 Posts: 6

Thank you !!
I get it running ...
I have to change
int16 My16bitsData[] = {0x1122};
to
int8 My16bitsData[] = {0x11, 0x22};

Ciao

Ttelmah · Joined: 11 Mar 2010 Posts: 19359

Or just reverse the bytes.

Key here is _byte order_. When you type 0x1122, this is a 16bit value, with the LSB to the right. The PIC puts the LSB into the low byte in memory, so will store the value internally as 0x22, 0x11. When you define the int8 array, you are loading this with the 0x11 first, so you store 0x11, 0x22.

Best Wishes

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

If you want to use CRC16 with the standard polynomial 0x8005, then it is possible to use the highly optimized implementation from the Code Library.