bugAVR Downloader/UploaDEr - Bugs: bug #18581, safemode destroys fuse bits

 
 

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bug #18581: safemode destroys fuse bits

Submitter:  None
Submitted:  Sat 23 Dec 2006 06:54:00 PM UTC
   
 
Category:  None Severity:  3 - Normal
Priority:  5 - Normal Item Group:  None
Status:  Fixed Privacy:  Public
Assigned to:  fischl Originator Name:  stefan noll
Originator Email:  -email is unavailable- Open/Closed:  Closed
Release:  None Programmer hardware: 
Device type: 

Fri 02 Feb 2007 04:32:08 PM UTC, comment #3: 

AVRDUDE stops now if communication between USBasp and target isn't possible.

Thomas Fischl <fischl>
Group Member
Sun 07 Jan 2007 09:59:57 PM UTC, comment #2: 

After some private email exchange with Stefan (who unfortunately
opened the bug tracker anonymously so he cannot add a comment
himself), this appears to be an issue with avrdude talking to
USBasp before some part of the communication has been settled
correctly.  Thus, the initial readout of the AVR is just junk
(it reads a wrong signature, and consistently reads all fuses
as 0).

It needs to be clarified how it can be ensured that avrdude
won't start prematurely.

Joerg Wunsch <joerg_wunsch>
Group administrator
Sat 23 Dec 2006 10:09:31 PM UTC, comment #1: 

Well, the purpose of safemode is not to prevent the operator
from writing to the fuse bits at all, but rather to prevent
inadvertent fuse bit changes resulting out of flakey (usually
simple bit-bang) programming hardware.  Actually, the first
implementation of safemode even prevented any writes to the
fuse bits (unless you disabled it using -u), and that caused
the majority of users to object.  Additionally, safemode never
writes anything to the fuses without asking the operator.

If you tell us more about your setup, and in particular some
analysis about why the fuses might have been read wrong
initially, perhaps there will be some help to you, and/or
some additional improvement to safemode.  Right now, it
already reads each fuse three times, and refuses to continue
if these three readings disagree.

Joerg Wunsch <joerg_wunsch>
Group administrator
Sat 23 Dec 2006 06:54:00 PM UTC, original submission:  

hi,

this kind of "safemode" destroyed the fusebits of three of my avrs.
when on startup the fusebits read wrong, the safemode writes back the wrong fusebits.
could you please implement a "real" safemode that refuses the write access to the fuses and not a recovery mode?

sincerely,
stefan noll

Anonymous

 

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Carbon-Copy List
  • -email is unavailable- added by fischl (Posted a comment)
  • -email is unavailable- added by joerg_wunsch (Posted a comment)
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    Follow 5 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2007-02-02 fischl StatusIn Progress Fixed
        Open/ClosedOpen Closed
    2007-01-07 joerg_wunsch StatusNeed Info In Progress
        Assigned toNone fischl
    2006-12-23 joerg_wunsch StatusNone Need Info

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