A USB logic analyzer is a very useful tool for our electronics projects, which we can add to our collection of measurement instruments for very little money.
Unlike an oscilloscope, which allows us to visualize analog signals, a logic analyzer only detects logic levels. Therefore, it “only” allows us to visualize digital signals.
So, in what circumstances is it useful? Have you ever had, for example, a setup that wasn’t working or an I2C device that wasn’t communicating, and you would have liked to “see” what was happening in between? Well, then a logic analyzer would have come in handy.
With a logic analyzer, we can visualize the digital signals of an electronic circuit. In the case of communication systems like UART, I2C, or SPI, which we frequently use in Arduino projects, it is even possible to decode the transmitted data.
As often happens, until not long ago, a logic analyzer was a fairly expensive device. But, for a few years now, cheap USB logic analyzers like the one in the photo have become popular, which we can find for 5-6€ on AliExpress or eBay.
This logic analyzer model allows visualizing up to 8 signals on the computer, with a maximum frequency of 24MHz. The voltages it can measure range from 0V to 5.25V, considering anything above 2V as HIGH. Therefore, it is compatible with 3.3V and 5V signals.
Given its price limitations, these specifications are sufficient for most home electronics projects. As mentioned, it is also sufficient for decoding UART, I2C, and SPI signals.
Part of the reason for its low price is the lack of a screen; it only has the electronics to record the signals. To visualize the signals, it is necessary to connect it via USB to a computer and use one of the various available software programs.
One common one is Saleae Logic, which is often recommended on the seller’s page or in the device’s documentation, available at https://www.saleae.com/downloads/. Although it is designed for the brand’s analyzers, it also works with these cheap devices.
However, the most recommended software is Sigrok PulseView. PulseView is an Open Source project available at https://sigrok.org/wiki/PulseView.
It is compatible with a wide variety of digital analyzers. It allows visualizing the different channels, recording the signal, exporting it, and performing measurements on it. Its use is very intuitive, and its interface is quite pleasant and comfortable to use.
Furthermore, PulseView adds various decoders that allow us to obtain the data transmitted in the recorded signal. The decoded data is conveniently displayed below the corresponding signal fragment, making it easy to visualize.
In short, a logic analyzer is a useful, inexpensive, and simple measurement instrument that, thanks to PulseView, we can get the most out of. It should undoubtedly be part of our list of favorite tools.
