Older 1999-2007 model year Ford vehicles don’t come with an aux input audio option and they have a cd changer under the seat instead. I made an Arduino shield that emulates the CD changer and injects my iPhone’s audio pretending to be a CD.
The shield also handles intercepting the car headunit’s playback commands when you press the physical radio buttons on your car so it does a second emulation of a earphone clicker and passes headunit playback commands back to control the phone over the aux cable.
In short I can control my phone’s audio playback using my retro radio headunit using only a wired connection and no Bluetooth.
My schematic and source code are available at https://github.com/ansonl/FordACP-AUX
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