September 13, 2022


About 1,5 years ago I designed & 3D printed a very simple USB foot pedal that I use for PTT (Push To Talk) with virtual meetings. After heavy use I managed to break the USB port on the microcontroller I was using so it stopped working.

I could have just bought a new Adafruit Feather 32u4 but at $20 it’s in my opinion quite expensive for what you actually get these days. Since using that microprocessor, Raspberry Pi has launched their own microcontroller called RP2040 and their tinker board called Raspberry Pi Pico. Not only does this board cost $4 but has dual cores and the ability to act as an USB host. That’s not all, the fact that this board is open and a stable target makes it a great opportunity to rewrite the horrible C++ code in Rust. I’ve become a big fan of the language but never used it with microcontrollers so this was a great opportunity to try it.

I redesigned the sketch to fit a RPI PICO and wrote the code and posted it on github as usual. There is some fun jank as the chip expects the interrupts to be signaled to the controller by poking some register, hence why I used statics to ensure that the address wouldn’t be empty.

What surprises me about this is how good the Rust developer experience translates to working with microcontrollers. With the setup in the repo, all you have to do is run cargo run --target=thumbv6m-none-eabi --release and cargo will build, pack and program the RPI PICO without you having to install toolchains, programmers etc. It just works out of the box.



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MAY CONTAIN HACKERS 2022 MCH is a huge hacker camp in the Netherlands that runs every 4 years (with some timeline adjustments due to COVID). I attended the previous version