Can I run Android Auto on a tablet via the Line-in on my car headunit?

[Android Central Question]

I'm wondering if I can run Android auto on a 7" tablet (I'm thinking a samsung) in my car and simply connect it to my existing headunit via the line in.
The car I'm getting in a few weeks has glare issues due to console design and I figured rather than buy a headunit I won't be able to see, why not just connect a tablet. The only headunits that wont glare are £750+ and I'm just not going to pay that, but I want all the voice controls and satnav that comes with Android auto (I have it in my other car).
My Questions are:
1) Can I run Android Auto on the tablet natively so it looks like the car headunit screen?
2) Can I just use my phone as a hotspot for the tablet to have it all work or do I still need to connect the phone via a cable to the tablet?
3) The only mics I seem to be able to find need to be wired to the device via the headphone jack, how do I get around this as I only have one jack on the tablet? I figured there would be loads of bluetooth devices on the market, but they seem to be headsets or inappropriate for car usage.
4) Anything problems I've not thought about ?

 

[bblhed]

Ugh, this is a yes and no type of thing. yes you can but no the UI will not be exactly the same there are some minor differences in layout and your phone or tablet may have more features than a head unit like the ability to report things, like speed traps and break downs, in Google maps.

First off if you have a decent size phone you might want to just run Android Auto on that and skip the extra step of using the tablet. If you go this route you can get a Bluetooth to FM converter (Amazon) that you can hook to your car so that when you start the car the Bluetooth goes on and automatically starts Android Auto for you, this is what I do, and my phone microphone works fine.

If you go the way you want to then you are probably going to be stuck with the microphone on your tablet. There is also the added security problem of a tablet in the car, the logistics of mounting, connecting, pairing, moving, and storing it. I tried this for about two days and gave up because for me a larger screen wasn't worth the hassle and I wear bifocals so if I'm saying that there might be something to it.

I drive a few different cars and only one of them has an Android Auto head unit. Aside from the head unit being rigidly fixed in the car and switching to night mode when I turn on the headlights there is nothing that makes the larger screen better than my 5.5 inch Pixel 3a screen. Unless you are at a very complex intersection most of your interaction with Android Auto is audio interaction not visual. I highly recommend using Waze for navigation instead of Google Maps, and use it for everything even if you are just driving 2 miles to the local store, the alerts can be worth it.

Good luck, I hope this helped.

 

[Cheenis22]

Thanks for the response bblhed, much appreciated. Did you use a particular ROM for the Android Auto or just go for the standard one?
I found a video which was much more indepth than I wanted as they were sticking everything in the double din space and making their own dash bits, but I think I now have a plan.
To answer your points:
1) I've got a pretty small phone so I'm after the larger screen
2) The plan is to have the tablet in a removable state, so security isn't any more of an issue than it was before.

I've detailed what I'm thinking of doing below, but first some questions.

Questions:
A) If I am using a USB DAC to output sound, will the mic still work in the headphone socket, or will android/ the device shut down the headphone socket (as it is overridden by the DAC)?
B) If the headphone socket is overridden, can I put a 3.5mm jack splitter in after the DAC so the Mic can be connected, or are those output only?

My plan is to find spaces for most of the bits as they are generally just wires. The wires will then escape from the trim so I can connect the tablet and mic. I've found that you can get an OTG charger cable which gives me a USB plug and also charges through a normal micro USB point. I'll add a 12v charger with a high amp socket to ensure it can charge the device.
The OTG cable gives me 3* USB + 1* mini usb to charge so I can have all the bits I need connected.
I'm planning the following:
1) A USB DAC
2) Standard in car mic (connected via the headphone jack; i.e., this cable will be visible on the dash)
3) My phone if I need to have it wired to the tablet for it to work
4) Option of a USB stick with music/ films.

Costing this up I'm at:
£3.25 - OTG cable and splitter
£6 mic
£8 high amp 12v charger
£75 USB DAC
£95 7" Galaxy Tab A

The USB DAC is a total extravagance, but I'm hoping I'll hear the difference in sound quality.

The bonus of this set up is not only that it saves me a stack against a replacement headunit, but it also means I can use the tab to watch films in my camper when I'm not driving. The only thing I'm finding a bit unnerving is that this doesn't appear to be common... nobody seems to know much about it and I'm wondering why given that it seems so logical and easy to me.

 

[Cheenis22]

Sorry, I've just answered my own questions. The DAC takes over the soundcard function, thus it deactivates the headphone jack. It then only acts as 1 way so I can't put a splitter on the other side. Looks like I might have to forgo the DAC and just get a splitter for use either through the USB or through the headphone jack... unless I could find a nice bluetooth or NFC based microphone. Just bluetooth and something to charge it, no 3.5mm jack to connect it. Does anybody know of one?

 

[Cheenis22]

Will Android auto/ google assistant work with a bluetooth microphone such as: https://www.amazon.co.uk/Nolan-Live...ag=hawk-future-21&ascsubtag=UUacUvbUpU6565765 If this doesn't come up it's the Alead Nolan LiveMIC2 Bluetooth Wireless Microphone.

If the soundcard of an android tablet is overridden (in this case by the USB DAC) can I still use the USB port to run a microphone in, or is the microphone only possible to use via the tablet's inbuilt sound card?

Sorry for the flurry of questions!

 

[bblhed]

In answer to your question about what ROM I am using, I just use the one from the US play store. I would love to get my hands on the next generation build to see how I like the new layout and color scheme but I am not that advanced.

As for splitting your headphone jack, here I do know a bit but probably only enough to be dangerous. Lets call the audio jack in the device the audio jack, not the headphone jack because it does both input and output. In my experience once you plug into the audio jack Bluetooth input and output for audio is disabled, your experience may differ. You might want to get your hands on an audio cable, one you don't mind ruining, that has the jack on the end for speakers and microphone and experiment with it. Rig a splitter so you can send audio out to the stereo, and audio in (microphone/mic) to the android device from a mic. remember the ground for the mic and audio out is common, and once hooked to the car it will also be common with the car, do not add an extra ground connection from the car frame to the microphone in an effort to save wire, that will cause a ground loop and a "dirty" audio signal. Microphone ground must come from the connection with the android device to avoid ground loops.

Something I can not stress enough is this, please whenever possible do not irreversibly alter the vehicle or its wiring including but not limited to cutting any wires to access a signal or function of that wire. The number one regret of almost everyone that has ever done a modification of a car of any kind is cutting things to install a stereo, followed closely by loud exhaust. Always alter the audio equipment to connect it to the car, not the car to hook it to the audio equipment, that is advice you will pass on some day after you did not follow it or had to deal with someones mess because they didn't follow that advice. There is a huge aftermarket that sells harnesses to hook an aftermarket stereo into your car's wiring harness without altering the cars wiring, and you can also get mounting kits to install a stereo, please use them, you won't regret it.