> > From: piclist-bounces@mit.edu on behalf of > pp5ms > Sent: Wednesday, November 21, 2018 3:14 PM > To: piclist@mit.edu > Subject: (PIC) 16F887 - strange behavior > > During these tests and new firmware versions, the hardware virtually stay= s > on all the time, or when I turn off and on to test the system startup, it > is a few minutes without power. > Five days have passed that something happened that I only noticed later. > > This MAY be due to an internal node being charged via invalid pin voltage= s during shutdown. eg several pins may be held at 5V initially and decay to zero over different periods. As one decays faster than the other an internal junction is forward biased and stores charge in an insulated node that causes havoc. Unusual but not unknown. Test: With power off in the fault state, short all pins to ground with a conducting bar. If you can short many or all at once to ground it's good, but even running van earthed wire along the pins can help. *IF* this works, look at the circuit for conditions where pins may be illegally biased during shutdown or startup. I have seen this and similar happen on a number of occasions. Russell McMahon --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .