USB pedals for a software modular synth would be a good project, too.

From https://news.ycombinator.com/item?id=44120903 :

> BespokeSynth is an open source "software modular synth" DAW that can host LV2 and VST3 plugins like Guitarix, which can also add signal transforms like guitar effects pedals. Tried searching for an apparently exotic 1A universal power supply. Apparently also exotic: A board of guitar pedals with IDK one USB-A and a USB-C adapter with OSC and MIDI support; USB MIDI trololo pedals

From "Python notebooks for fundamentals of music processing" https://news.ycombinator.com/item?id=40555387

> Additional Open Source Music and Sound Production tools:

Brandon's Semiconductor Simulator lists what all is not yet modeled. "Basic equations of semiconductor device physics [pdf]" https://news.ycombinator.com/item?id=44723304 :

> Notes re: "Brandon's circuit simulator", which doesn't claim to model vortices in superconductors or the Quantum Anomalous Hall Effect, for example; https://news.ycombinator.com/item?id=43942279#43948096

electronics.stackexchange has CircuitLab built-in; TinkerCAD has circuit assembly and Python on Arduino in a free WebUI, but it's not open source. Wokwi and Pybricks (MicroPython on LEGO smart hubs over web bluetooth) are open core.

LPub3D is an open source LDraw editor for LEGO style digital building instructions. LeoCAD works with the LDraw parts library.

"WebUSB Support for RP2040" https://news.ycombinator.com/item?id=38007967 :

> USB 2x20 pin (IDE cable) GPIO

FWIU Fuzix and picoRTOS will actually run on a RP2040/2350W. 2350W have both ARM-Cortex and RISC cores, but something like an STM can work for months on a few batteries.

Linus Learns Analog Circuits