A method and system for waking up a primary microcontroller of a controller in response to a change in a control pilot signal generated by an external device coupled to the controller includes coupling the external device to an input port electrically connected to the controller. A control pilot signal generated by the external device is received by the input port and outputted to a monitoring device of the controller in low power mode. The monitoring device in low power mode polls the control pilot signal and upon detecting a valid change transitions to normal power mode to output a wakeup pulse to the primary microcontroller, which in a sleep state receives the wakeup pulse and wakes up to execute instructions stored on the primary microcontroller. In an example, the system controls recharging of a battery by a charging station which outputs a pulse width modulated control pilot signal.