MKS SERVO42B is 3d printer closed loop stepper motor NEMA17 MKS SERVO42 developed by Makerbase that prevents losing steps. CPU is STM32F103C8T6 ARM 32-bit Cortex™-M3 CPU Core,72 MHz. Magnetic encoder is Allegro's A1333LLETR-T Contactless 0° to 360° angle sensor IC ,12bit .This Project open source hardware and code,support platformio build and upload firmware...
https://github.com/makerbase-mks/MKS-SERVO42B/wiki/MKS-SERVO42B-User-Manual
the very first link is to http:://github.com/Misfittech/nano_stepper (two colons at the start). oops!