[Alpha le ciel] is building this stepper motor module as the first of many Raspberry Pi hats meant to provide the Raspi with the hardware for robotics applications.

Rather than having the host Pi communicate directly with the stepper drivers, the 3+Pi features an onboard STM32F302CBT6 that handles the actual motor control.

PicoCNC, the Raspbrerry Pi Pico based CNC control board, has finally emerged from development by Phil Barrett of Brookwood Design, which has a web store on Tindie.