[OpenTRV-dev] AVR (328P) EEPROM puzzler

[Damon Hart-Davis]

Before posting links to code I wanted to see if there was any interest, or knowledge of similar behaviour elsewhere.

It’s a small piece of code in a big system.

Rgds

Damon


> On 20 Mar 2016, at 10:38, Bo Herrmannsen <bo.herrmannsen at gmail.com> wrote:
> 
> Or a link to it if the link is not in the  post he linked to :-D
> 
> 2016-03-20 11:30 GMT+01:00 Stuart Poulton <stuart at poulton.org.uk>:
> Damon,
> 
> You might get a better response if you post the code.
> 
> Stuart
> 
> On 20 Mar 2016, at 07:25, Damon Hart-Davis <damon at opentrv.uk> wrote:
> 
> > I have posted a question on the Arduino forum here:
> >
> > http://forum.arduino.cc/index.php?topic=387790.msg2672097#msg2672097
> >
> > Rgds
> >
> > Damon
> >
> >> On 18 Mar 2016, at 20:12, Damon Hart-Davis <damon at opentrv.uk> wrote:
> >>
> >> Hi,
> >>
> >> We are seeing some bizarre behaviour where when we try to write a 16-byte key into EEPROM it fails to ‘stick’ properly the first time.  If the board is power-cycled and the key is written again, it appears to stick as expected.  (There’s some subtle sub-wierdnesses also.)  This uses some ‘careful’ update routines that we use extensively elsewhere and seem to be fine with blocks as large as 8 bytes long (node IDs).
> >>
> >> Lots of use of my favourite search engine is failing to show any evidence of this being a common problem.
> >>
> >> I have reviewed the code repeatedly and found a minor wrinkle which is merely an inefficiency, not an error.
> >>
> >> Anyone fancy doing some detective work and then pointing out exactly why I shouldn’t be allowed near a keyboard any more?  B^>
> >>
> >> Rgds
> >>
> >> Damon
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> >
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