Hi Neil,

I would say don't be lazy and check the pins manually, but if you really
don't want it the 'hope and pray' technique could be the following:

NOTE: I could be completely wrong on this, do not trust on me and do not
send the bill for me of your damage if you try this out <grin>

1. run your circuit as normal
2. pick a pin from the possible two
3. feed it by 10V for 5us
4. see if the chip made a reset or not - if yes this should be the MCLR/Vpp
pin, if not you might burned out the PGD pin.

This is because according to the datasheet when Vpp reaches the Vihl level
for Thld0 long it enters to programming mode and it will reset all states,
all pin becomes input, PC will be 0 - so a reset occurs.

Tamas




On 4/16/07, PicDude <picdude2@avn-tech.com> wrote:
>
> I have a PIC-based project installed in my car and it has the ICSP wires
> routed out of it and wired to a DB-9 connector.  But now, some months
> later,
> I can't find the DB-9 pinout.  Would it be possible (using a multimeter)
> to
> identify which wires correspond to which ICSP pins, without tearing back
> into
> the car?
>
> Some specifics on the application circuit:
> - PIC16F913
> - MCLR is not connected to anything (using internal MCLR).
> - Vdd is at 5volts.
> - RB7/PGD is not connected to anything.
> - RB6/PGC is connected to one side of a tact switch and the other side
> goes to
> ground.  Yes, I have access to the tact switch.
> - Vss is connected to a ground wire coming out of the gauge.
>
> With this, I figure I should be able to determine Vss, Vdd and PGC
> relatively
> easily.  From the code, RB7/PGD is currently setup as an input, and MCLR
> defaults to an input.  I'm thinking I can connect a 0V-5V signal to any
> input
> pin though a resistor and being an input, the voltage at the pin should
> follow the external signal.  But with both MCLR and PGD being inputs,
> would
> it be possible to differentiate between these two?
>
> Cheers,
> -Neil.
>
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