You may also want to make sure that the low-voltage-programming fuse is 
set to not allow.  I've had lots of weirdness with that fuse set, and I 
think it probably exists on the 877 but it's been so long that I don't 
remember for sure.

-forrest

On 3/17/10 5:01 AM, Matias Vidoni wrote:
> Hi people
> I have a circuit where I have a pic16f877 that commands four water pumps.
> The connections between the pic and the pumps is made this way:
> PIC ->  5k6 resistor ->  Bc337 transistor ->  relay ->  contactor ->  pump
> I start the pumps in secuence and when a presure sensor signals, I shut down
> every pump one by one.
> When the last pump stops, the pic resets, and it should not.
> Could it be my interface pic-pump the problem?
> Could it be some EMI interference from contactors or pumps resetting the pic?
> The most strange thing is that it resets only when the last pump power off.
> the software is ok, because I put the circuit in my workbench, with leds
> simulating the pumps and it works great.
> If somebody has a clue, let me know.
> Thanks a lot!
> Matias
>
>    

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