md3848
Level: Wannabe

Joined: Fri. Nov 14, 2014

Location: IRAN

Posted by md3848:
Thu. Dec 12, 2019 - 09:22 PM

hi

I think for every byte of data, we need one byte CRC

then if we have 64 byte data - we must have 64 byte CRC !!! That doesn't sound logical

// this is the format of the CRC ( n < x )

data : (x) bit

polynomial : (n) bit

CRC : (n-1) bit

example ( decimal format, data 2byte ) :

data : 12345 ( binary : 11 0000 0011 1001 )

polynomial : 305 ( binary : 1 0011 0001 )

CRC : 255 ( binary : 1111 1111 )

but my problem is that > now for data=12345, crc=255 **but** for crc with this value ( 255 ), we have other data ( 2byte ) with this crc!!! for example : data=255 and ...

when we have several data with similar crc, ITS NOT GOOD

What can we do now?

my answer is that, for set eror ( The probability of crc for several data (2byte ) being equal ) to zero, we must have CRC with number bits equal to Data

even for test, i wrote an softwer with c# ( for calculate all crc for data between 0 to 2 byte/65535 )

where is my problem? crc is not good idea or i mistake? I got a little confused

http://www.ghsi.de/pages/subpage...

This topic has a solution. Jump to the solution.
mahdi damirchilu, my blog : dmf313

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Last Edited: Fri. Dec 13, 2019 - 12:42 AM