Hey,

Thanks for all your help. It definitely helped us reach the solution,
because in the process of trying these things Francois discovered the
problem (by just "trying" something), which ended up removing the
problem - or so it seems. We'll see on Friday when they are installed
in the field.

So to recap. We noticed that at times when powering up the PIC it goes
into endless resets. These happen at crazy speeds. If you opened a
serial interface to the PIC your screen would literally be flooded
with the boot up message.

So the solution was grounding 4 open outputs. They were definitely
configured as outputs. We confirmed this 3 times. They were all on
PORTB, and we set TRISB=0x00;
You guys sent a lot of mails (thanks for that), didn't someone
somewhere mention that even if a pin is configured as an OUTPUT, that
it should still be grounded? If this is not a standard, why would an
open output cause a reset when millivolts are applied to the pin (ex.
static electricity from the body when approaching the device)?

I will let post our results on Friday.

Quintin Beukes



On Wed, Sep 23, 2009 at 11:34 AM, Tamas Rudnai <tamas.rudnai@gmail.com> wrote:
> On Wed, Sep 23, 2009 at 9:11 AM, Quintin Beukes <quintin@last.za.net> wrote:
>
>> Further, he confirmed that the MCLR is used as a programming PIN. I'm
>> not sure if that is an open input/output. We are performing tests on
>> this now.
>>
>
> What Olin and others suggested about putting an unused pin to output and
> drive them active low is not applicable to this pin. As Jan-Erik pointed out
> the VPP/MCLR/RE3 pin can be configured either MCLR or digital input, but not
> output. Also there is no internal pull-up for that pin, so no matter if you
> use it as MCLR or digital input that pin needs an external circuit anyway.
>
> Tamas
>
>
>>
>> Q
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