Hi all

I have a project using the PIC 16F876A. I'm having a problem with that appears to be the program memory resetting or erasing randomly on power up.

I'm using a wall wart at 12 vdc to power up the system. An LM340AT produces 5v for the processor, which is fed through an on-off toggle switch to the PIC. I have a .1mfd decoupling cap between +5 and ground at the PIC.

I program the chip, and the device works fine. Power it on or off several times OK. Then it will cease working. Using my Epic programmer and Micrcode studio plus to verify the program it shows either all 0s of 3FFF instead of program. Device reprograms OK. Ive tried different chips witrh same result. Problem seems worse if I leave the switch on and unplug and plug the 12V power supply, which makes me suspect transients.

I have MCLR tied to 5V with a 3.3k resistor.

Any ideas or power supply design tips greatly appreciated! This problem is a project killer!

Thanks