> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On
Behalf
> Of Matias Vidoni
> Sent: 17 March 2010 11:02
> To: Microcontroller discussion list - Public.
> Subject: PIC resetting frequently
> 
> 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

Do you have a diode across the relay to suppress the high voltage when
you switch it off?

Mike

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