(1) drv8801/8833/8871 https://electronics.stackexchange.com/questions/531470/how-to-troubleshoot-a-drv8833-motor-driver-module-problem (2) btn7970/7971B (2.1) https://electronics.stackexchange.com/questions/510755/how-to-use-motor-drivers-with-h-bridge-and-pwm-input-to-control-direction-and-s (2.2) https://electronics.stackexchange.com/questions/582623/sensing-voltage-drop-across-the-load-in-the-h-bridge/582626#582626 (3) tmc2130/2160/2208/2209 (3.1) https://raspberrypi.stackexchange.com/questions/135191/rpi-pico-micropythpn-controlling-tmc2208-tmc2209-stepper-motor-driver-problem/135194#135194 (3.2) https://electronics.stackexchange.com/search?tab=newest&q=tmc2130 (3.3) chat.stackexchange.com/rooms/133206/discussion-between-john-and-tlfong01