Simulate Arduino, ESP32, and More with This Open Source Web Tool

Is your circuit design the problem? Or is it your code? Or is it your rat’s nest of jumper wires on the breadboard? Diagnosing issues in any field is always about isolating variables and David Montero Crespo's Velxio open source online web tool will let you do that by creating working simulations with virtual development boards that actually run code.

Velxio is the kind of tool that I’ve seen many, many people asking for. It lets you build out a circuit based on a development board, like an Arduino UNO Rev3 or a Raspberry Pi Pico, then run code right there in the simulator.

That’s great for proving a circuit design before you order parts, but I think it is particularly useful as a diagnostic tool. If your real-life LED isn’t blinking like you expect, simply rebuild the circuit in Velxio, paste your code, and run the simulation. If it doesn’t work there either, you know it is an issue with your code or circuit design. If it does work, you know it is an issue with your wiring. There are even a serial monitor and an oscilloscope, which should further aid in debugging and troubleshooting.

Though I should note that the oscilloscope function didn’t seem to work for me, so it might be buggy.

There are already many popular development boards to use in Velxio, including many Arduino models, ESP32 development boards, and the Raspberry Pi Pico / Pico W (though no Pico 2, yet).

You can even drop an entire Raspberry Pi 3B into the simulator and use it. That isn’t just GPIO, either. You actually get a virtual file system to use and can interact with the Raspberry Pi OS (Linux) through the terminal.

On the programming side for the development boards, you can code using C++ (like in the Arduino IDE) or Python. There are also libraries you can install and use, just like you would normally do.

Of course, a circuit isn’t complete without components and there are quite a few to use, but the catalog isn’t exactly comprehensive. There is, for example, a MPU650 gyroscope/accelerometer there, which is pretty neat. But there isn’t a diode.

So Velxio may not yet be ready for primetime, but it is far enough along that you should probably check it out. You can do that right away with the online editor, or go to GitHub if you want to find all of the files to play around with on your own machine.