I'm about to build a circuit (on breadboard), which should do the following: A PC and a smartphone should be connected by audio cable (audio out from pc goes to smartphone's mic in , audio out from smartphone goes to PC's mic in). Moreover, when receiving a message via usb, an arduino board ("between" PC and smartphone) should simulate pressing the play/pause-button of a wired headset's audio controls (used to trigger a specific event in a smartphone app). According to http://dl3jin.de/galaxy-data/headset_scm.jpg , basically two lines of the audio cable need to be short-circuited. I'm a electronics noob (only basic, theoretical knowledge), so I don't know how to realize the circuit. A colleague told me that this could be achived by using a MOSFET which is controlled by one of arduino's I/O-ports.
Is there an easier way to do this? Which components are needed/would you recommend? (Which arduino board, which additional components?) Is it necessary to protect the PC against the short-circuit? (how?)
Thanks in Advance, Cheers, Martin