PIC16F877A PINs goes high during reset

bells_electronics · Joined: 05 Dec 2009 Posts: 40

Sir,
I am using PIC16F877A to drive sensitive Gas Valves, everything is working fine, I am just facing a Problem when the controller powers up it sends HIGH to all the pins of the microcontroller.
Is there any way that the microcontroller never send HIGH to all the pins during reset/powering up
Best Regards
Bells

SherpaDoug · Joined: 07 Sep 2003 Posts: 1640 Location: Cape Cod Mass USA

Is the PIC setting the pins high, or just setting them to inputs? Maybe you need pull-down resistors to keep them in the low state till the PIC sets them otherwise.
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dyeatman · Joined: 06 Sep 2003 Posts: 1933 Location: Norman, OK

It shouldn't so something is wrong. Which pins are you referring to?
I know the Port A pins come up as inputs so the only way for them to go
high would be with pullups.

Give us the compiler version and show the initialization code from the fuses
all the way to where you set up all the Port Pins in Main. We don't need to
see any interrupt routines since they should not be enabled until after the
ports are set..
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