Computer Interfacing
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Unable to detect CRC8


 

       Computer Interfacing Forum Index -> Error detection and correction
Author Message
Shenawy
Guest







Dec 20, 2014 1:35 pm

Hello, I need some help in identifying the algorithm of CRC

I have tried to test the crc if it's true CRC or not
by applying the method introduced by Gregory Ewing in his article www(dot)cosc.canterbury.ac.nz/greg.ewing/essays/CRC-Reverse-Engineering.html
Quote:
Due to the superposition principle, if changing a message by xoring it with a bit pattern B1 causes its CRC to change by C1, and another bit pattern B2 causes the CRC to change by C2, then xoring the message with (B1 xor B2) should change the CRC by (C1 xor C2). If that doesn't happen, the algorithm can't be an ordinary CRC algorithm

and I found that it's a true CRC

Then I have tried all CRC8 algorithms using the program reveng : reveng(dot)sourceforge(dot)net/
It failed to find the algorithm , may be I miss using the program ?

NOTE : We don't have spectial bit messages ( 1 bit set message or all zero message )

Here are some samples of messages and CRC
first 2 bits are ID
second 2 bits are CRC
third 2 bits are the counter
the rest of bits are data
for example this message :
Code:

ID CRC  CNTR  DATA
20  67  CD    410C0000
ID is 20
CRC is 67
Counter is CD

and the rest of bits are data
if next message is
Code:
20DDCE410C0000

note that counter CE is increased by one

Code:


2067CD410C0000
20DDCE410C0000
2040CF410C0000
2028C0410C0000
20B5C1410C0000
200FC2410C0000
2092C3410C0000
2066C4410C0000
20FBC5410C0000
2041C6410C0000
20DCC7410C0000
771F02E0EEA7EC7
774212E0EEA7EC7
774222D0EEA7E87
77E932D0EE97E97
77BA92B0EEC7EC7
77310A2F0EEA7EC7
77B70B2F0EE97E97
77220C330EE97E97
77330D330EE97E87
77D40E330EE97E87
778C0F370EE97E87
216632000000
219AB3000000
210E38000000
21F2B9000000
21B43A000000
2148BB000000
21673C000000
219BBD000000
21DD3E000000
2121BF000000
21DC30000000
2120B1000000
1316902001900
1316582001900
131EA92001900
131660A2001900
131E90B2001900
131600E2001900
131EF0F2001900
Also we have the following (which I am not sure if it contains CRC or not )
682

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