Designing Embedded Hardware

Tools for Debugging

For the systems described in this book, the minimum debugging tools you will need are a multimeter and an oscilloscope. Logic analyzers are very expensive tools that allow you to monitor and diagnose digital signals. They are essential for developing high-speed and complex systems (especially those with buses), but you should be able to get by without them for the designs in this book. Certainly, for a self-contained microcontroller, a logic analyzer is of no use at all.

A multimeter allows you to measure current and voltage, but more importantly, it also allows you to do a continuity test between two points (and verify that there is a physical, and therefore electrical, connection). However, do not do continuity tests if there are sensitive components in your system. The continuity test may damage them.

Warning

Don’t assume that just because a signal is present at one end of a trace it is present at all points along the trace. Check everywhere with an oscilloscope probe, and use your multimeter to confirm that signal paths are connected properly.

The oscilloscope allows you to view waveforms within your system, and as such, it is your principle debugging tool. Oscilloscopes range from the crude and ancient to the expensive and sophisticated. While you don’t need to spend $100k on an oscilloscope, you will need an oscilloscope that can accurately view waveforms. That rules out the $20 antique you picked up from Mr. Gorsky’s garage sale down the road.

You will ...