bugAVR Downloader/UploaDEr - Bugs: bug #50350, EFuse high order 4 bits writes...

 
 

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bug #50350: EFuse high order 4 bits writes incorrectly. Fix attached.

Submitted by:  None
Submitted on:  Sat 18 Feb 2017 05:16:06 AM UTC  
 
Category:  None Severity:  3 - Normal
Priority:  5 - Normal Item Group:  None
Status:  None Privacy:  Public
Assigned to:  None Originator Name:  Mark
Originator Email:  -email is unavailable- Open/Closed:  Open
Release:  6.3 Programmer hardware:  STK500v2
Device type:  atmega32u4

Sat 18 Feb 2017 05:16:06 AM UTC, original submission:

When programming the atmega32u4(m32u4) EFuse, AVRDude trys to write the upper 4 high bits as "0". These 4 bits are unused by the uP and are to be unprogrammed, set to "1". This causes a mismatch when read for verification since the uP ends up allowing 2 of these bits to be programmed:IE "1 1 0 0 i i i i".
In the avrdude.conf file under m32u4, it is set to write "x x x x i i i i". By updating the avrdude.conf file to "1 1 1 1 i i i i", the upper 4 bits are properly left as a "1" while the lower 4 bits are written according to user input. This corrects the issue.

Example: writing "F3" to the EFuse returns "C3" after programming since AVRDude trys to write "03" and the uP mistakenly accepts 2 of the upper "0"s. After updating the avrdude.conf to default the upper 4 bits to unprogrammed ("1"), the upper 4 bits are properly left as unprogrammed (unused) and the EFuse properly returns as "F3".

Anonymous

 

Attached Files
file #39782:  m32u4 EFuse write bug.JPG added by None (42KiB - image/jpeg - See EFuse Bug Fix.JPG for change to avrdude.conf to correct the issue.)
file #39783:  EFuse Bug Fix.JPG added by None (33KiB - image/jpeg - See EFuse Bug Fix.JPG for change to avrdude.conf to correct the issue.)

 

Depends on the following items: None found

Items that depend on this one: None found

 

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    Follow 2 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2017-02-18 None Attached File- => Added m32u4 EFuse write bug.JPG, #39782
        Attached File- => Added EFuse Bug Fix.JPG, #39783

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