A logic analyzer is an excellent tool for capturing many digital signals at once and displaying their timing relationships. It is particularly useful in verifying and debugging digital circuits. This tutorial is intended to provide a quick overview of a logic analyzer tool and its uses in analyzing and decoding data flowing on multiple signal lines or bus in a digital system. The logic analyzer tool is extremely helpful in troubleshooting problems arising from timing violations and transients on buses. In this article, I am going to use the SCANALOGIC-2 educational kit from IKALOGIC to illustrate very basic features of a logic analyzer.
Several types of electronic measurement tools are used to test and verify digital circuits. A digital oscilloscope is one of the most commonly used tools in an electronics lab. The oscilloscope is used for general-purpose signal viewing and it allows to make accurate measurements of various attributes of the signal such as rise- and fall-times, peak amplitude, frequency, the elapsed time between edges, etc. Typical digital oscilloscopes have up to four signal inputs, which means you can simultaneously observe four signals and their attributes. However, the oscilloscope cannot help you when you need to measure digital signals on a 32-bit microcprocessor bus simultaneously because it doesn’t have that many channels. A logic analyzer tool can serve this purpose. Although it grew out of an oscilloscope, the logic analyzer have different capabilities, and it measures and analyzes signals differently than an oscilloscope. Instead of measuring analog details, the logic analyzer only detects the logic state of a signal. Logic analyzers can have over 100 channels (some sophisticated ones have over thousand channels). Because they can capture and display logic states of many signal lines at once, logic analyzers are very helpful for verifying time relationship between the signals. They can also decode information sent over the microprocessor bus and present them in a meaningful form.