' RECOMMENDED BY 'acidtech' IONMOTION FORUM.
XOR CHECKSUM CALCULATOR EXCEL CODE
' THIS CODE WORKS CORRECTLY COMPARED WITH PROFESSOR CHEN JIAGI- CRC CALCULATOR TOOL Xor with 0x1021 which I understand is the CCITT polynom.īTW did not see your moved post CNC16 - do you want to move this thread onto that one? Shift crc one bit left (multiply by 2) then So it seems like parsing every byte is happening.Īnd crc & 0x8000 seems to be flagging that if the leftmost bit out of 16 (2 bytes)is a 1 then <<8 has to be shift a whole byte to left. I think that << shift left 1 bit achieves a similar result to multiply by 2 (dec or hex)at the bit level.
Looks like crc = crc xor'ed with selected byte in packet shifted 8 bits to the left? not sure what is happening there. Cannot say I am there yet but have learned quite a bit today along the lines ofĪssume crc starts as &H0 (- some of these CRC16 start with &HFF it seems)įor byte = 0 to quantity of bytes in the packet - 1Ĭrc = crc ^ ((unsigned int)packet << 8) Have been attempting to build my own pseudo English from your sample and a lot of digging into C syntax. Great to have use of a tool that matches what RoboClaw expects. The answer you quoted as 30D - should that be hi byte 0x03 and not 0x93 I think Select CCITT and Hex then insert hex values as one continuous string Thanks for the link on that reply - that will be very useful. This thread relates to the CRC16 code example on page 36 of the new manual.
XOR CHECKSUM CALCULATOR EXCEL SOFTWARE
I have found some other coded examples I am trying to analyse to find/build a matchup.Ĭontinued from replies to Major Software Release My C is nothing like good enough to read that example. It looks like a simple enough thing to code if I could get my head around exactly what it is achieving.
Please supply a pseudo English code explanation for the CRC example you provided in C on page 36 of the new manual. I don't have C to test for answers using the sample. I can plug your values into an array and when I can get my code to produce your answer I will know I am getting somewhere. I believe the CRC16 is now going to be 2 bytes. I suggest a format something like "80 26 00 00 07 D0 00 00 00 2C xx yy" where xx and yy are replaced by the ACTUAL CRC16 checksum values you would get - This example is for port 128 command 38 Accel 2000 as 4bytes and some speed as 4bytes. PLEASE provide a line of data that shows exactly what is being sent for a typical command. I code my own routines in Visual Basic - available libraries not useful to me I think. Great to see some of that stuff available now.
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