CFA635 with PIC host

[PeteG]

That works, its now returning 44552 or 0xAE08, which, although not correct, is much closer to the value it should return 22914 or E50E. Will re-check algorithm, Thanks

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[cosmicvoid]

That works, its now returning 44552 or 0xAE08, which, although not correct, is much closer to the value it should return 22914 or E50E. Will re-check algorithm, Thanks

If you are using this CRC code, https://forum.crystalfontz.com/showpost.php?p=25380&postcount=9 then what you have no longer matches, so that could be the reason. The differences are subtle, you should re-copy it exactly.

Also, 0xE50E does NOT equal 22914, FWIW.

 

[PeteG]

Got it working! The fix was simple in the end. I had incorrectly assumed "data" in the algorithm refered to the display buffer, so labled my display buffer array as "data", but "data" is just just a buffer used in the CRC calculation, Changing my display buffer data to "display_buffer" sorted it. Thanks to Cosmicvoid for your help.

 

[PeteG]

I am trying to read in the switch data. The CFA635 sends the first report correctly, but then it sends another 2 packets with 00 command codes, which it should not be sending at all, as this is the host to CFA command code. After that it does nothing and wont respond. Do I have to acknowledge a keypress packet back to the CFA635?