[Android Head-Units] jeffc83:
Awesome; glad the process worked for you too man! I truly thought we were screwed but for some reason, I thought your issue was more hardware related. We're still not sure as to why we all have a different MCU version but I suspect it might have something to do more with our cars such as the MY and model. I would like to know how they integrated it and if it can be modified.

Many uses for the MCU include but are not limited to:

Aside from the obvious aesthetic challenges of making it look right, there is other advantages these units offer that Android itself and the hardware it's made to run on does not natively handle:

Sound Controls: Balance, Fader, Audio levels, pre-amp out levels, and hardware controlled tones, mixing and switching of audio inputs etc. All these are (in any modern car stereo unit) controlled by a Analog Audio Processor, for example in the case of the AN-21 U, the Sound Processors with built-in 3-band Equalizers - BD37534FV is the Audio processor chip.

Video controls: Video input and output switching and video overlays/OSD. These units provide Aux input, rearview camera with separate switching, DVD etc. as well as Aux video out all these inputs and outputs (android being just one of them, more on this later) are controlled by a separate chip, again in the case of the AN-21 U the FMS6502 − 8 Input, 6 Output Video Switch Matrix

DVD/CD playback: Android currently has no real provision to handle DVD/CD drives for movies and music playback. A dvd unit much like a cheap home dvd player with it's own firmware is included in most of these units and it's video and audio outputs routed through the processors described above.

Bluetooth: This frustrates many, as these unit provide bluetooth out of the box but do not support any of the "simple" things any android device supports if it has bluetooth. The main complaint is lack of support for BT ODBII readers, but also, bluetooth keyboard, bluetooth filesharing and many others.

The key here lays in the Bluetooth Profiles supported. While android supports many profiles natively, these units bluetooth is a separate board not even visible to android, that supports the few android doesn't, notably the Hands-Free Profile (HFP) and Advanced Audio Distribution Profile (A2DP) AS CLIENT. Researching the subject of using an android tablet as a headphone will return many thread like this one. To date I have not found a solution that doesn't involve external or additional hardware. Hence, the separate bluetooth hardware to handle that, of course as anything else, with it's audio routing through the audio processor described above.

Steering wheel controls (SWC) and Canbus interface

Front face buttons/knobs and illumination

I-pod interfacing

Radio and TV tuners. While some Android devices do support some tuners, those are usually specific to manufacturer specific hardware.

Power state and switching such as provision to turn the unit off when ignition is off, video input switching when in reverse, antenna and amplifier switching and Video playback block for laws Compliance.

Video player and music player. While android definitely can handle those tasks on it's own, these radios supply built in players separate from it. Mainly because they already had that functionality before adding an android board to the equation