Another technique is to use a speed/direction control scheme where ENABLE is connected to a GPIO output and the PHASE is pulse-width modulated. In this case, both direction and speed are controlled with a single signal. ENABLE is only used to disable the motor and stop all current flow.
When pulse-width modulating PHASE, a 50% duty cycle will stop the motor. Duty cycles above 50% will have the motor moving on the clockwise direction with proportional control; 100% duty cycle represents full speed.
Duty cycles below 50% will have the motor rotating with a counter clockwise direction; 0% duty cycle represents full speed.