This pedal it’s a C++ DSP FX unit made with a Raspberry PI. It’s been originally built and made by Electrosmash
It takes the input signal from a guitar (bass it’s also supported if you swap one of the capacitor so it can process lower frequencies), samples it in realtime and feeds it to a C++ script, which outputs a modified signal (the outcome is based on the script)
It has a limited processing power/sampling rate (the PI is limited to 40KHz) so it’s mainly a tool used to understand how to write and apply DSP techniques to a realtime audio signal
Here’s the code for base clean effect (clean.c) – a sample script that just copies the signal from the input to the output buffer
Using the clean effect as a base, it’s possible to create complex effects and audio processing.