A USB logic analyzer is a very useful tool for our electronics projects, which we can add for very little money to our collection of measuring instruments.
Unlike an oscilloscope, which allows us to visualize analog signals, a logic analyzer only detects logical levels. Therefore, it “only” allows us to visualize digital signals.
So, when 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 going on in there? Well, then you would have benefited from a logic analyzer.
With a logic analyzer, we can visualize the digital signals of an electronic circuit. In the case of communication systems such as UART, I2C, or SPI, which we frequently use in Arduino projects, it is even possible to decode the transmission data.
As usual, 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 model of logic analyzer allows you to visualize 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 HIGH to be anything above 2V. Therefore, it is compatible with 3V3 and 5V signals.
Given its price limitations, these specifications are sufficient for most home electronics projects. As we have already 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 to a computer via USB and use one of the different available software options.
One common option is Saleae Logic, which is frequently recommended on the seller’s page or in the device 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 you to visualize the different channels, record the signal, export it, and make measurements on it. Its use is very intuitive, and its interface is quite pleasant and easy to use.
In addition, PulseView adds different decoders that allow us to obtain the transmitted data in the recorded signal. The decoded data is conveniently displayed under the corresponding fragment of the signal, making it possible to visualize it comfortably.