What would a burnt out PIC do?

Hi, Brick. It sounds more like you've got an issue with the PCB traces. Especially if you're using a reasonably-sized iron (25 watts or so if not temperature-controlled), I'd guess at least one of the traces is going somewhere it shouldn't.

You didn't mention what tools you used to do the circuit board artwork, or if you hand-etched the board. But considering it's such a simple circuit, how about just making a Xerox of the artwork, and a Xerox of the schematic, and just mark off the nodes on each with colored markers? Always look at this first. Actually, if you've got a spare board, you can just use washable markers and use the board itself.

Another thing you might want to try is ohming out the traces, particularly if you etched this yourself. Look both for opens and shorts between traces and between pins, and shorts from the PIC pins to power or GND. If your board is populated, set your DVM on the 20K ohms range to avoid smoking something.

Good luck Chris

Decades ago there was an author, back in the earlier days if microprocessors, that wrote several books on hardware debugging, unfortunately I can't remember his name at the moment.

One of his ideas was called the "static stimulus tester." This was a little project board that you would spend a lot of time carefully building up. It had debounced switches and leds on it. And it plugged into your microprocessor socket. What it would let you do is observe the inputs and generate outputs a clock edge at a time if need be, it was static. With that he showed how this little gadget would point out many of the little errors that we all seem to make. Making one of those for a PIC should not be a difficult task.

Perhaps for your little project you could do this or a smaller subset of this to help diagnose the problem.

did you account of the unused legs for pullups? the test would be to unsolder the chip and put it back in the bread board and see if it still works there? there must be some other inputs you mite be over looking also, for example it could depend on how your code it written when it comes to reading a input, you may need to pull up or down all other inputs or something ? floating inputs are not good.

Next time, solder onto an IC socket, and then *gently* place the PIC in that.

This technique helped my dad and me *a lot* when we were playing with

Michael

could be, of possibly your soldering iron or the socket it's plugged into isn't correctly earthed.

what you describe could also be a faulty power connection to the chip (either +5V or 0V

get yourself a low-voltage continuity tester

also

IC sockets are cheap and can make firmware upgrades less painfull. in addition to helping prevent electrostatic and thermal damage.

Bye. Jasen

It did turn out to be the PCB traces, good idea Chris! Thanks for everyone elses' replies too. I'm using a 30 watt iron now, I want to get a smaller one when I get the chance. There was just a short between traces that I couldn't see with my naked eye. My solution was simply to leave more space between them on the new board. I use the laser printer and etching solution way to make the board.

That idea about using a socket is a good one also. This is just a stupid little project to learn about pics, but if I do anything where I'm going to want to be changing code then I will do that.

I'm always glad to see how helpful people in this group are. Trying to get into electronics has been stressful at times and the advise that I get from people here helps me keep at it, which is nice because it is starting to get really fun :-).

Brick

Hang in there, it gets better.

In the interim, the convention is to bottom-post; it follows the natural flow of conversation.

Cheers! Rich