bugAVR Downloader/UploaDEr - Bugs: bug #42267, jtag3isp fails to read lock and...

 
 

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bug #42267: jtag3isp fails to read lock and fuse bytes directly after changing lock byte

Submitted by:  Matthijs Kooijman <matthijs>
Submitted on:  Fri 02 May 2014 09:43:30 AM UTC  
 
Category: NoneSeverity: 3 - Normal
Priority: 5 - NormalItem Group: None
Status: NonePrivacy: Public
Assigned to: NoneOriginator Name: Matthijs Kooijman
Open/Closed: Open

Tue 06 May 2014 12:40:18 PM UTC, comment #1:

I just did some quick testing with avrdude 6.1, which also shows the same problem.

Matthijs Kooijman <matthijs>
Fri 02 May 2014 09:43:30 AM UTC, original submission:

I'm having some trouble reading and verifying the lock bits with jtag3isp. jtag3 works as expected. I'm using Avrdude 6.0.1.

It seems that (shortly) after writing the lock byte, the fuse and lock bytes no longer read correctly. When the clock is slower, only the first few reads after the write fail, suggesting that this is somehow a timing problem.

The problem did not occur when writing the fuse bytes, only when writing the lock byte.

See the attachment for an extensive log of commands and output, along with inline comments by me showing the problem.

I haven't tried actually sniffing the SPI bus to see what values are actually returned by the device being programmed. I might try that if you think it helps (and my bus pirate is fast enough ;-p).

Matthijs Kooijman <matthijs>

 

Attached Files
file #31298:  log.txt added by matthijs (44kB - text/plain)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -unavailable- added by matthijs (Submitted the item)
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    Follows 1 latest change.

    Date Changed By Updated Field Previous Value => Replaced By
    Fri 02 May 2014 09:43:30 AM UTCmatthijsAttached File-=>Added log.txt, #31298

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