Arduino based Blaupunkt CD Changer emulator

This Arduino Micro emulates a CD changer (CDC-A08) to enable the Aux input on the radio (a Blaupunkt Travelpilot DX-R52). The circuitry is just for inverting the TTL signal coming from and going to the radio. I want to use the next and previous track commands to control playback on my Android phone via Bluetooth. The protocol was reverse engineered using a Scanalogic 2 Pro analyzer from IKALogic.