debubbing procedure-help

The only "general procedure" for testing something is to see if it works, to the best of my knowledge.

There are as many ways of interfacing to a PC as there are designers. Try the other side of google - they have a fantastic web search facility.

Good Luck! Rich

Hi, Prad. Debugging a PCB is a bit of an art form. You have to take into account the cost of failure (what you could smoke if it doesn't work), as well as how much time (and possibly money) you want to spend to ensure it's OK.

I kind of wish you'd been more specific about how you're connecting your circuit to the computer. At one extreme, if you're connecting via serial port, just let 'er rip -- as long as you're not going to apply more than +/-25V, it's pretty much indestructible. On the other side, connecting a card to the bus can lead to big problems and easily smoke the motherboard or power supply.

As far as the PCB itself goes, start by visual inspection of the bare board with a magnifying glass -- you at least have a chance of catching whisker shorts and continuity before you do anything else. Ohm out the power traces to look for dead shorts, as well as any lines that are right next to each other.

For most circuits, you should be able to do a DC power check without connecting the board to the computer. Install components (socketed if possible on the prototype) and give that a try. If you're connecting to a bus, you might want to buy/beg/borrow/scrounge a socket and cobble together a DC test fixture, with power from a PC and appropriate pullups/pulldowns to ensure solid logic states.

Where you go from there kind of depends on what computer connection you're making. I'd suggest that you might want to scrounge older PCs, so you can have one ready to sacrifice for occasions like this. Also, external printer port/serial port/network cards can be helpful here, if you can find ones for your PC. It's always better to smoke a card than a motherboard.

Good luck Chris