also referred as mic power mode wherein the microphone 350 is operated to collect audio signal and transfer the collected audio signal to the electronic device 200 in certain embodiments the mic operation mode activates the mic switch 328 and connects the mic conductor 314 to the microphone 350 the 1 wire control 322 is in a sleep state to operatively disconnect the mic connector to the external i o port 326 through the i o interface 324 the accessory 300 may set the mic line at high impedance that indicates its readiness for mic communication mode or load the mic line to indicate its readiness for exiting communication the electronic device 200 may control the mic supply with proper impedance by setting desired bias mic line voltage for each operation mode and start or end the mic communication mode if the predetermined mic line condition for entering or leaving the mic communication mode is met one skilled in the art will recognize that the above described 1 wire communication mode is only one communication example in another embodiment a modulation ac operated above audible frequency may be adopted to superimpose the data line over the power line for mic line data communication in another embodiment the accessory control ic 320 is configured to have the mic switch to disconnect from the mic signal coming from the microphone 350 such that the mic data communication could use any frequency signal even in an audible frequency fig7 illustrates a block diagram when the accessory is in an accessory.