pin 12f683

[jcleaver]

this functions but not as expected at first pin to v+ caused change
than after short time v- caused change which is what i would expect
dont quiet understand inital operation but this is doing what i want
thanks

[jcleaver]

this program works but still get times when it functions backwards
should be gnd to pin to work but sometimes after downloading program
it will be just the oppisite + volts to pin

any changes that will stop this from accuring

[Bruce]

Are you sure it's not a hardware problem? I ran this on a 12F675, and it works
exactly as expected. No matter how many times I re-program it.

[jcleaver]

bruce:
not 100 % sure but seems strange that sometimes + volts cause the pic the way - volts should than sometimes it works just the right way - volts causes the pic to respond properly is there some sort of start up or setting that could cause this maybe pullup not coming on?

[dharwood]

Quick question:
What are you using as V+ for your input signal ? +5v +12v etc.....?

I had a project where I was trying to read a ~12v input (DCD on a rf modem) and it would sometimes work, other times not. Set up a voltage divider so that my input voltage would not exceed 5v and from that point on, it has worked as planned.

HTH,

Dale

[mister_e]

You have to give us your WHOLE schematic, there's no obvious reason why it shouldn't work.

If you supply line is pure crap, it will give you crap. In car it's usual. Tie ALL unused pin to somewhere first. ALL floating i/o in car apps (and everywhere anyways, trust me or not i don't care)... is often a killer situation.

Now if one of your input is MCLR and you didn't use the right voltage divider, your PIC will fall into programming mode... too bad.