If it don«t help tying MCLR to Vdd there is probably severe noise in chip
supply.

1) Are you certain that ni spikes etv are conming in return fron outputs,
or overshooting the inputs? Maybe try inserting resistors close to chip in
serial to the suspected pins?

2) Are the PIC supply stable and well decoupled?

3) Or, I dare say, there is a program error. We all do them... Have you
made a very simple test progran that make all output operations, and detect
reset?

PS We are all interested on avoiding problems of this kind, so please tell
if You find anything! DS

Regards
/Morgan

At 22:46 1998-01-25 -0800, you wrote:
>hello
>
>I am working on a project that involves controlling electric motors
>through relays with a PIC16F84. The motors and relays have the
>appropriate back EMF suppression circuits, but I find that the PIC
>occasionally resets when the motor and/or relay swithes on/off. I suspect
>that this has something to do with the MCLR pin on the PIC.
>
>Can anybody advise a way of making the pic resistant to this type of
>resetting, or possibly disabling the mclr pin?
>
>Any assistance that you could give would be most appreciated.
>
>Mark
>
>

Morgan Olsson, MORGANS REGLERTEKNIK, Sweden, ph: +46 (0)414 70741; fax 70331
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