Pico Makes Capable Logic Analyzer

A frequent adequate microcontroller venture is to create some sort of logic analyzer. In theory, it need to be very uncomplicated: seize some electronic inputs, keep them, and display screen them. But, of system, the satan is in the aspects. To start with, you want to grab info speedy, but you also want to look at the result in in serious time — really hard to do in program. You might also will need enter conditioning circuitry until you are glad with the microcontroller’s input qualities. Eventually, you require a way to dump the knowledge for examination. [Gusmanb] has tackled all of these complications with a basic analyzer crafted close to the Raspberry Pi Pico.

On the front and again finishes, there is an optional board that does rapid degree conversion. If you never thoughts measuring 3.3 V inputs, you can forego the board. On the output aspect, there is customized application for exhibiting the outcomes. What’s genuinely fascinating, although, is what is in in between.

The simple PCB is fully optional.

The Pico grabs 24 bits of knowledge at 100 MHz and offers edge and pattern triggers. This is outstanding simply because you need to have to look at the facts as you keep it and that eats up a couple instruction cycles if you consider to do it in software package, dropping your highest clock fee. So how does this venture regulate it?

It works by using the Pico’s PIO units are auxiliary devoted processors that are not very highly effective, but they are pretty rapidly and deterministic. Two PIO recommendations are adequate to cope with the function for very simple situations. Nevertheless, there are two PIOs and each has four independent condition machines. It nevertheless takes some perform, but it is simpler than hoping to run a CPU at a couple gigahertz to get the exact same influence. The fast trigger mode, in unique, abuses the PIO to get greatest speed and can even get the job done up to 200 MHz with some restrictions.

If you want to try out it, you can use practically nothing a lot more than a Pico and a jumper wire as very long as you never require the level conversion. The undertaking web page mentions that custom made software avoids applying OpenBench software, which we get, but we may well have gone for Sigrok drivers to avert owning to reinvent too several wheels. The creator mentions that it was less difficult to roll your personal code than conform to a driver protocol and we get that, way too. Nevertheless, the software program appears to be like awesome and even has an SPI protocol analyzer. It is all open up source, so if you want other protocols ahead of the writer receives to them, you could usually do it on your own.

If you do want a Pico and Sigrok, we’ve covered a project that does just that. Most of the logic analyzers we use these days we build into our FPGA layouts.