The PCA9629A is an I²C-bus controlled low-power CMOS device that provides all the logic and control required to drive a four phase stepper motor. PCA9629A is intended to be used with external high current drivers to drive the motor coils. The PCA9629A supports three stepper motor drive formats: one-phase (wave drive), two-phase, and half-step. In addition, when used as inputs, four General Purpose Input/Outputs (GPIOs) allow sensing of logic level output from optical interrupter modules and generate active LOW interrupt signal on the INT pin of PCA9629A. This is a useful feature in sensing home position of motor shaft or reference for step pulses. Upon interrupt, the PCA9629A can be programmed to automatically stop the motor, re-start motor, enable extra steps or reverse the direction of rotation of motor. Output wave train is programmable using control registers. The control registers are programmed via the I²C-bus. Features built into the PCA9629A provide highly flexible control of stepper motor, off-load bus controller/micro and significantly reduce I²C-bus traffic. These include control of step size, number of steps per single command, number of actions from 1 to 255 or continuous rotations and direction of rotation. Re-start motor for new speed and operation without waiting for motor stop. A ramp-up on start and/or ramp-down on stop is also provided with re-enable ramp-up or ramp-down to change the ramp rate curve on the fly.