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Testing & Debugging

Prerequisites:

  • Assembled prototypes
  • Inspection finished

Tools:

  • Bug-tracking software
  • Multimeter
  • External power supply
  • Oscilloscope, logic analyzer, device programmer

Next Step:

Once you’ve inspected and checked everything over you’re ready to move on to testing and debugging.

Your circuit, like all circuits, has a flow to it. There are things that happen, in order, that allow other things to begin happening. It could be as simple as a switch getting flipped, which powers a 12V to 3v3 power supply, which then powers a micro-controller. Debugging is all about understanding the flow of your circuit. Understanding the inputs and outputs to each phase of your circuit’s power up, right through its operation, will allow you to pinpoint the places where things have gone wrong and ultimately fix them.

Start at the beginning. What happens first? Where is the first sign that things are bad? Where is the last sign that things are good? Once you have the bookends of your problem you can start checking the points in-between them. The simplest way to do this is with a multimeter. Measure the voltage of a part and compare it back to your expectations. If it’s right then you can move forward, if it’s wrong then you need to go back. You should eventually find the exact spot where things go from good to bad, and will be able to dig into the cause of the bug, and hopefully fix it.

Once you’re done debugging, you’ve made the changes necessary to make your design work, and you’ve learned everything you can from the current revision you’re ready to spin another batch of prototypes and start the verification phase over again.

If you didn’t have any fixes with this batch, or fixes small enough to apply as ECOs (Engineering Change Orders) during production you’re ready to move on to qualification & environmental testing if necessary, or straight on to production.

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