You Can Now Use Your Raspberry Pi Pico as a Synthesizer Module in Your EuroRack

EuroRack is a semi-formal standard for synthesizer stations. The standard is designed to be modular, so producers can slot in whatever synthesizer modules they like into their EuroRack. Both the racks themselves and the modules come in various sizes, but those sizes are standardized in a way similar to server racks so that you can be sure everything fits together properly. This also makes it easy to design your own modules that fit perfectly into a EuroRack. There are endless ways to build synthesizers and other electronic music hardware these days, but if you like the new Raspberry Pi Pico you should check out Rory Allen’s EuroPi module.

The new Raspberry Pi Pico is a microcontroller development board that is both powerful and affordable, with makes it perfect for use in an inexpensive EuroRack synthesizer module. Similar modules on the market today can easily cost hundreds of dollars, but a single EuroPi module can be made for less than $25. You also get the added advantage of being able to reprogram the Pico’s RP2040 microcontroller to suit your own needs. And because the Raspberry Pi Pico is very compact, the EuroPi module won’t take up much space on your rack. Finally, the EuroPi PCB is built entirely with through-hole components that anyone can easily solder.

While the Raspberry Pi Pico is an extremely capable development board, especially considering its low price, there is something it lacks: a DAC (Digital-to-Analog Converter). That means that it has no way to output a true analog signal. But it can simulate an analog signal with PWM (Pulse-Width Modulation). By itself, that will output a signal with a series of “steps” like line drawn without anti-aliasing. That is noticeable and will result in sort of “robotic” sound. To address that without resorting to using relatively expensive DAC chips, Allen designed the EuroPi PCB with RC (Resistor-Capacitor) circuits that smooth out the PWM output signals. You get four digital outputs, for analog outputs through those RC circuits, and two potentiometers for adjusting the outputs. How you choose to use those is completely up to you, because you’re free to program the Pico to behave however you like. If you’re looking for a small and affordable synth module for your EuroRack, this seems like a great choice.