# CRC calculation

• 11-17-2008, 02:50 AM
tom_rosenback
CRC calculation
Hi, does anybody know how to figure out the CRC algorithm if a given code + CRC string is given? I have got several strings consisting of code + matching CRCs but donīt know how to calculate the CRC in question so that I could produce more code strings. Here are some samples (16bit code + 4bt CRC):

0010101000011101 + 0000
0010101000011111 + 0001
1000110011101101 + 0001
0000000000000100 + 0010
0011100011001110 + 0011
1000110011101110 + 0100
0001011110101100 + 0100
0010101000011110 + 0101
0011100011001101 + 0110
0001011110101111 + 0111
0011100011001100 + 1001
0011100011001111 + 1010
0001011110101101 + 1011
0000000000001000 + 1011
0000111100001101 + 1100
0000000000001100 + 1100
1111111111111111 + 1101
1000110011101111 + 1101
1000110011101100 + 1110
0001011110101110 + 1110
1111111100001101 + 1110
0010101000011100 + 1111

These codes come from a RF (433MHz) sender like the X10 products.

Hopefully there is someone out there that can help me!!
• 11-17-2008, 02:24 PM
ClockWorK
http://en.wikipedia.org/wiki/Cyclic_redundancy_check
The Computation section is particularly good.
• 11-17-2008, 04:18 PM
tom_rosenback
Thx for your link. I have had a look at the wiki page, without results. I have tried to do the calculations as mentioned in the wiki but canīt manage to get the correct CRC calculated... Is there anyone who can help me with this?

Any help in any way is appreciated!
• 11-17-2008, 05:16 PM
tom_rosenback
I am not sure if this is a CRC or what it is, but at least it calculated somehow out of those code strings.