// the find
torvalds/GuitarPedal
Linus learns analog circuits
Linus Torvalds' personal guitar pedal project — an RP2354-based effects unit with a 128x128 OLED, rotary encoders, and a TI TAC5112 audio codec. This is a hobbyist embedded C project, not a production framework. It's interesting primarily because the author knows what he's doing at the hardware/firmware level, and the commit history reflects genuine iteration on a real device.
The modular PCB design is genuinely thoughtful — separating the MCU board from the codec board lets you swap layouts without re-spinning everything. The pitch shifter implementation is technically honest: it's delay-based, not FFT-based, and the README says so plainly including the tradeoffs. The DSP primitives (biquad, envelope follower, LFO, PIO-based I2S) are self-contained header files that are easy to read and adapt. The 10-band EQ using precomputed coefficient tables (generated by the Python scripts in Software/scripts/) avoids floating-point trig at runtime on the RP2354.
Documentation directory is described as 'very optimistic' by the author himself — there's one file in it. The USB audio interface is explicitly marked work-in-progress and unreliable, which is a real gap if you want to use this as an audio interface alongside a DAW. The 0.35mm-pitch HiRose BM28 connectors are not hobby-friendly — you will need a stencil and reflow oven, not a soldering iron. All DSP is single-precision float with no mention of latency measurements or tested performance headroom on the RP2354's dual M33 cores, so you'd have to characterize that yourself before adding effects.