The DRV8323SRTA chip is used to control the speed of the motors. With the motor driver set to 1x PWM mode, the commutation is done based on the feedback of the motor's hall sensors. (see datasheet for specifics). To measure the current through the motor, a single 40m ohm resistor is used with the driver's internal amplifier to read out the current and send it to the microcontroller, using an analog signal. The motor drivers are connected to the topboard's microcontroller using 4 digital pins, to be able to set the direction of the motor, to enable/disable the motor braking, to set the speed(or rather torque, but the relation is not that clear) and a pin to notify the microcontroller if there are any faults present. There are also a shared SPI bus connecting all four motor drivers to the microcontroller, to be able to set the settings at bootup. This SPI could also be used to turn on/off the braking and change the motor direction, however it was easier to implement the code, with there being a dedicated pin for these actions. The SPI bus is also used at bootup, to detect whether the motor drivers are present and working correctly.