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Re: CB030, A 68030 SBC for hobbyists [message #10107 is a reply to message #10104] Sun, 21 August 2022 15:03 Go to previous messageGo to previous message
mikesmith is currently offline  mikesmith
Messages: 80
Registered: March 2018
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mikesmith wrote on Sat, 20 August 2022 21:15

Hopefully I can work out the corruption problem
In all cases, I'm seeing bits geting set in the high nibble: d->f, b->f, 5->7, a->e. No obvious address sensitivity. The rate is low; those are 6 samples out of a 690k file.

Interestingly, it always looks like bits that are getting set were 1s in the previous byte:

  50,bb -> 50,fb 
  24,5f -> 24,7f
  56,a3 -> 56,e3

Copying the file many times (i.e. exercising the CF read / write path) doesn't seem to introduce any new corruption, so that seems to exonerate the filesystem / disk.

Now I need to find a way to validate the file transfer path. ZModem is fairly aggressive with its checksumming, so that doesn't leave a whole lot of options.

[edit]

Looks like serial reception is unreliable at 9600bps, and there's enough corruption that occasionally we hit a CRC collision and ZModem lets the corrupted bits through. Uploading at 4800bps is reliable, but obviously that's no fun. Going to have to see if I can work out if the UART FIFO is being overrun, or if something else is going on. I had the UART configured at IPL2, which would have been a problem, but after looking at the CPLD and moving it to 3 that hasn't helped.

[Updated on: Sun, 21 August 2022 21:46]

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