For the Zyklochron, I replaced the simple Darlington drivers with a TMC2208. Initially I ran the module in legacy mode. One motor alone ran absolutely silently, but as soon as both motors were running, a kind of whistling noise was heard. Possibly some kind of resonance. So I wanted to address the TMC2208 via the UART interface to solve the problem by fine tuning the parameters. Therefore I wrote this simple library to be able to address the TMC2208 with an ESP32.
You can find a detailed description on my website