An electronic device may operate in standby and active modes. A headset may be coupled to the electronic device. The electronic device may have audio codec circuitry. The audio codec circuitry may use general purpose input-output circuitry in handling button and headset activity during active mode. Processing circuitry may be used to reconfigure the audio codec in real time. When the electronic device is in the standby mode and activity is detected, the codec may be configured to provide an interrupt signal to a power management unit that wakes the device. When the electronic device is in active mode and no user inputs are received within a given period of time, the central processor in the electronic device may place the device in standby mode.