The PCA9629 is an I²C-bus controlled low-power CMOS device that provides all the logic and control required to drive a four phase stepper motor. The device is intended to be used with external high current drivers to drive the motor coils. The PCA9629 supports three stepper motor drive formats: one phase (wave drive) mode, two phase (full step drive) mode, and half-step (one-phase on and two-phase on) mode. In addition, the PCA9629 has four General Purpose Inputs/Outputs (GPIOs), which when used as inputs allow sensing of logic level from optical interrupter modules and generate an active-low interrupt signal on the INT pin of PCA9629. This is a useful feature in sensing home position of motor shaft or reference for step pulses. Upon interrupt, the PCA9629 can be programmed to automatically stop the motor or reverse the direction of rotation of motor. Also, any of the GPIO pins can be used as an output pin, for example, to drive an LED to indicate different statuses of the motor controller or the motor. The output wave train is programmed by writing via the I²C-bus to the control registers in the PCA9629. Features built into the PCA9629 provide highly flexible control of stepper motor, off-load bus master, and significantly reduce I²C-bus traffic. The features include control of step size, number of steps per single command, number of full rotations, and direction of rotation. A ramp-up on start and/or ramp-down on stop is also provided.