CNC HAT Drives 3 stepper motors. It uses TI DRV8825 drivers with 1:32 microsteps. Onboard Arduino compatible ATmega328 microcontroller interprets GCODE commands come from Raspberry Pi's UART port. CNC HAT comes with GRBL preflashed, which can be modified via ICSP pins. 6 Endstop connectors, 3 function connectors + buttons and a head connector with spindle pwm, dir and probe pin is connected to the microcontroller. The I2C port is directly connected to Raspberry Pi's I2C1 line, so you can add displays, sensors and servo drivers to the board easily.