B.t.w, are you using "internal-MCLR" ?
Or how can the application interfere with the
programming ? Normaly (with "normal" internal MCLR)
the processor is held in reset-state until
Vpp is applied, so the code never runs...

Jan-Erik.

Peter Todd wrote:
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> On Tue, Jun 12, 2007 at 04:12:08PM +0100, Alan B. Pearce wrote:
>>> Also if I wait a day, burning works fine again,
>>> for about twenty or so burns.
>> This strikes me as a problem with LV programming bit being set, and the PGM 
>> pin not being held in the correct state.
>>
>> What programmer are you using? I seem to remember someone recently having a 
>> problem where they found their programmer was illegally changing some bits 
>> in the config word from what was specified, and doing something like this. 
> 
> The problem appears with both a PICStart+ clone and a PICKit2...
> 
> That said, sure enough I found it. Turns out the errata was applicable,
> namely that switching to the internal oscillator to 8mhz too soon
> actually causes the oscillator to overshoot, resulting in an out of spec
> condition. This didn't seem to affect my app at all, but it did cause
> programming to fail. Adding a half second delay at the very top of the
> program fixed the issue. Anything I did after the oscillator switch had
> no effect, for instance an infinit loop directly after the switch to
> 8mhz still failed, which the same infinit loop, with a five second delay
> before the switch worked fine.
> 
> What's really weird is it took a good 6 months of on and off development
> to even run into the problem. Yet I the code to switch to 8mhz was in
> there from the very start, and indeed was copied from another 16lf819
> using project.
> 
> Even weirder though was I was trying some months old firmware versions
> out, that now suddenly, and reliably, have the problem! It's like
> running into it once in a day causes the programmer, even after being
> turned off, to trigger it even with firmware that previously worked
> fine. All the time I was using the same three 16lf819's, and my "clean"
> ones that I could reproduce the problem with too were all from the same
> rail.
> 
> Embedded programming is downright wacky!
> 
> - -- 
> http://petertodd.org
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