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Stereo Head Unit Replacement - RasPi OpenAuto

14K views 45 replies 7 participants last post by  JohnWR 
#1 · (Edited)
I have been wanting to add an after market head unit for a while to add Android Auto functionality and a backup camera to the Sky.

In wanting to make a project out of it and not wanting to spend $500 on just a head unit I decided to build my own using a Raspberry Pi and 7" touchscreen. As of this posting I have the entire setup bench tested and working as I wanted.

Key Features I wanted:
- Backup Camera
- Handsfree calling
- Android Auto USB and Wireless (No compatibility with Apple CarPlay sorry)
- Extended delayed shutdown (device goes to "sleep" for 1 hour after car is off, explained later)
- Direct phone mirroring
- Customizable and upgradeable UI/OS

Current features missing:
- Steering wheel controls (to be added later using Arduino)
- No CD player (no plans to add one)
- FM radio (may or may not add, this one is a little trickier to add, currently being researched by software developers)

I plan on outlining my setup if people are interested. Will also post some pictures. Plans are currently to start the actual car install hopefully next weekend or the following. Spent about a month on trial and error experimenting and the code to run some of the features.
 

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#38 ·
Well I learned something new today. I thought the Monsoon system was only paired with the 6 CD changer (which I knew I didn't have) but I did find a UQ3 on my glove box. I'm no audiophile but I would not have guessed I even had a sub in the car from the way the audio quality seems.

Once again, thanks John for the invaluable info and ideas. I'm mostly relieved that the problem is clear now. So, is the solution as simple as sending the battery's accessory power to the amp? Looking at the connector wiring diagram I see a "Radio On Signal" and "Remote Radio Control Signal". Pins 1&2 are also L/R audio signal + which I don't understand.

It's sad that I would have preferred to not have the Monsoon now haha.
 
#39 · (Edited)
The head units are generally considered to be pretty weak, and changing it generally is considered to be the biggest step-change in sound improvement.

I too am glad that the mystery has been solved, and I think that ultimately you will be happier with the Monsoon than without it. You will have to reduce your output to prevent over-driving the amp.

Pins 1 & 2 are L & R XM audio (+), with pin 9 as the (-) for both channels.

Pin 3 is the 12-volt signal from the head unit to turn on the amp. Any time there is 12 V on that wire the amp will be on, and it gets its power straight from the fuse block, so control it carefully to avoid a dead battery.

Pin 15 Remote Radio Control mutes the amp when it sees 12 V. I left it un-connected.
 
#43 ·
Mid step update:

It's been a little while since I last updated and there has been an interesting "lessons learned" experience. I ended up having a battery that was at the end of its life and when I went for a trial run I must have drained the battery too much because I attempted to start the car and nothing. Wouldn't even charge on the charger after that and replaced the battery. Side note issue is I ended up bricking the Raspberry Pi due to under voltage (won't show SD card activity anymore) also corrupted the SD card...

Anyway, replacement battery, Raspberry Pi and Micro SD card.... plus redeveloping some of the scripts I had put together because I built them on the Pi and didn't save them :cheers: and I'm back to where I was 2 weeks ago. Installed the setup in the car and.... it works!

Currently Remaining:

- Finalizing Mic position, I currently have it clipped to the left side of the center console near my right thigh but haven't settled on that yet. (I haven't went through the mic placement post I've seen on here yet)
- Have not started routing or mouting the backup camera
- Setting up the usb hub in the glove box cleanly which will possibly route to the "cigarette lighter" plug in a near future update for passenger phone connection

Below is a picture of the unit in place, the AC controls aren't full snapped back into place but you get the idea

***Anyone know why no matter what I do my picture attaches sideways?***
 

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#44 ·
Mid step update:...............

***Anyone know why no matter what I do my picture attaches sideways?***
Looking good. Sorry about the setbacks.

Is there an under-volt protection circuit in your future?

I think what you have to do is put the picture on your computer, correct the rotation, and save it with a different name.
For some reason just saving it doesn't correct the orientation.
 
#45 ·
Hmm, I never realised you could brick an RPi by under voltage. Very strange.

As for Mic position, I posted about this years ago... I tried a number of places when I was using a Parrot Bluetooth setup. The best place I found was in the top left corner of the windshield, right where the factory put theirs. Go figure :)

Lastly, how did you end up clipping the screen in place - did you use speaker grill clips?
 
#46 ·
Hmm, I never realised you could brick an RPi by under voltage. Very strange...........
Maybe it wasn't actually undervoltage. There could have been surges or spikes during the process of the battery dying, trying to start the car, being charged, and then being replaced. It could also have been the loss of power in the middle of an initialization, read, or write cycle.
 
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