"Runar Gjelsvik" <(E-Mail Removed)> writes:

> I was looking at this site posted somewhere earlier:

>

> http://www.easics.be/webtools/crctool

>

> The thing I'm wondering is how do you calculate what polynom to use? I'm

> planning on serially send a data frame of about 72 bits. I was thinking of

> using manchester encoding and CRC.
The polynomials are selected from a pool of mathematically test

polynomials. In your case, I'd pick one of the wellknown ones,

e.g. the CRC32 used in Ethernet (and a lot of other places).

The longer CRC that you use, the better coverage (error detection) you

get. In general, the probability for an undetected single-bit error is

(2^N)-1:1 for an N bit CRC. This requires that the length of the frame

you send is less than 2^(N-1)*N bit, IIRC.

Regards,

Kai