DIY In Dash Android Tablet: A Worthy Quest

That's my fault for throwing the phone confusion in. Sorry about that.

The convertors/sound processing in headunits can be on the basic end most times this is true. The signal will eventually become some form of analog in order for it to be sent to an amplifier via rcas. I personally dislike using high level (speaker wire) inputs to an amplifier because you are essentially sending an amplified signal to be amplified again and the high level outputs from most headunits will distort or clip at a lower volume versus rcas. So it's kind of a toss up really because unless you have an amplifier with a direct optical input as well as all other equipment in-line (dsp, eq etc.) accepting and passing an optical signal, for most scenarios it would still end up analog to the amplifier.

 

While it's true that signal will end up analog at some point prior to entering the amp, there are still differences in purity. Like you said, high level inputs (while not terrible) aren't top of my list. The tablet will give you the ability to run a REALLY high quality DAC. The one I'll be using does 96Khz/24bit audio decoding. So HD FLAC files are now playable in the car!

One thing that was mentioned that I don't agree with is the need for the tablet to be taken with you. The Nexus 7 is SO cheap that it's permanent home will be the dash of the truck. I won't need to take it out for any other purpose aside from general maintenance. The idea of personal info being stored on the tablet is indeed a concern and I'll admit, not one I really thought about too much till now. The amount of personal info I'll be storing on there isn't much but access to my email is what worries me. I'm one of those people who believes that your email password is THE most important password you have. If you don't agree, think about it for a while and get back to me.

A simple lock screen could be used for security and I'm wondering if you could use Tasker to create some sort of unlock task based on RFID or even bluetooth. It's definitely something I'll need to look into and I appreciate you raising the issue.

 

PS: There was a LOT of progress made last week and I'll be posting some updates in the near future.

 

Any personal info should be safe guarded. However, your personal info and what you choose to secure is really up to you. Not trying to sway you away or even say you are wrong. Just saying that you are the only one who can decide what personal info you choose to secure. On the tablet being removed I was basing my statement on my personal preference of being able to remove for information security reasons mainly. I'm sure there are many tablet installs that permanently live in the vehicle and there is nothing wrong with that either. In the end it really is your money and what you want. I was only offering some kind of friendly observances and whatever I said can always be taken with a grain of salt. Above all I would like to see your finished project as I won't deny that tablet installs can be versatile...just not for me currently.

 

Don't get me wrong, I 100% agree it's something I need to address. Though I'm going to do so with a specific security protocol that I'm going to whip up. Like I said, build something such that when X bluetooth is present unlock the device. Or maybe just something simple like a pattern screen lock. I believe I'd be able to wipe the device remotely in the event it got stolen anyway. So essentially all I need is the device to be secure enough for me to realize it was stolen and then hit the wipe/kill switch from my side.

 

I'm sure tasker can accomplish this task easily. I paid for tasker many years ago so I don't really use any other device wipe apps that may exist. Bluetooth near or even GPS location could be used if you aren't worried about power consumption. RFID tags could be used too. I'm thinking you could use tasker to program an "arm" and "disarm" widget along with RFID tags so that when "armed" and it no longer senses the RFID tag nearby it will automatically lock itself completely and/or wipe personal information. It could send GPS coordinates via email but then that would require a working email account with personal information. When disarmed it can be removed without the device wipe. Pressing a button might not be what you want so might want to try finding a way to program it when the vehicle is on/off. Just my thinking out loud.

 

All of those are good ideas. Also, I'm wondering if I could use the steering wheel controls (emulated by a Joycon adapter I have yet to figure out) as a way to put in a password after the tablet wakes up. Making it easy to input the password with hands on the steering wheel. Then, if the incorrect password is put in X number of times, it wipes itself. Lot of possibilities to consider!

Update on the Build
There's definitely a lot of things that need consideration with this build and I'm realizing that now. The Dragonfly V2 USB DAC sounds GREAT! However, I can't seem to get enough output from it and that might be a deal breaker. Even with the Audison Bit1 master volume all the way up and the Nexus 7 volume all the way up I can't quite get enough volume. I'm going to poke around with it a bit more before I totally axe the idea but I'm not sure there's much more I can do.

But I did order a USB to Optical DAC which could really be a nice addition. Although the Bit1 doesn't have quite as high a sample rate as the Dragonfly, running optical into the processor means there will be ZERO noise coming from the RCA runs from the dash. The output issue should be solved too....at least I hope.

 

The optical DAC (which technically shouldn't be called a DAC for obvious reasons came in yesterday. One day shipping from Amazon is a beautiful thing. I popped it in and got the processor setup very easily. Plenty of output now. I didn't have much time so I just threw crossover protection and a bit of level matching on the system but really didn't get time to make it sound good.

NEED HELP
Has anyone tapped into the steering wheel control wires in the main harness? I recall seeing a wiring diagram a looooong time ago but it's been forever and I can't find it. I'm trying to use a Joycon adapter to emulate the steering wheel controls but I don't know if I'm using the right wires. Any help would be MAJORLY appreciated!

 

Well....I think I got most of it figured out. Let me know what you think!
https://www.youtube.com/watch?v=iW165hO7Okw

 

nice

 

Steven that is simply winning!!

 

Looks good. Did you mod the dash kit heavily or managed to keep it minimal?

 

Honestly, it wasn't that bad. A little less than an hour with the dremel and it was good to go. Wiring wasn't that bad either. I have a USB hub behind the dash with 4 ports on it that allows me to plug in various devices including the steering wheel control adapter. Power comes from a cigarette lighter/USB charger that I've wired into a standard Tacoma wiring harness adapter. Really just need power, switched power, and ground. I used a relay though I don't know if it was necessary.

 

Got more pics from along the way?

 

There's really not too much else to show. The tablet is a somewhat simple solution as long as you have a separate amplifier and processor. Behind the dash i have the USB hub I mentioned, the charger, and a flash drive. In addition to that, I have a USB dac that sends an optical signal to my processor. That's pretty much it. I can give y'all links to thing I bought to make it work if you want. A parts list sort of thing.

 

A parts list and software list would be great. I am not a great fan of the entune system in my 2015. I have been debating on installing my old system from my 2010 truck but as you stated in your first post the times are much different from 5+ years ago.

One thing is that I am a bit of an XM radio junkie and I would prefer to not use data to stream that service over an app. Have you run across any solutions for this in your research?

 

You could use an aftermarket radio behind the tablet to mediate extra sources like AM/FM/XM/CD/etc...

Also, his system is a fully amplified stereo. If you're not planning on adding amplifiers and beefing up the rest of your system, you'll need something like an aftermarket radio to provide power for the speakers.

 

^Man speaks the truth. You'll need amplification of some sort for sure. Whether it's the headunit or some separate amp. Having a headunit hidden inside the dash is a pretty good idea and I've seen it done a few times. It certainly helps with the handoff for bluetooth calls.

 

Here's a parts list that I used....
Microphone:

$11 VideoSecu High Sensitive Audio Pickup Device External Amplified Microphone Sound Voice Collecting with Bonus Warning Decal WD6

http://www.amazon.com/gp/product/B0053V5Z9W?psc=1&redirect=true&ref_=oh_aui_detailpage_o04_s00
Power adapter for Mic: http://www.amazon.com/gp/product/B00MBIYYJW?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00
USB OTG Cable *ONLY BUY THIS ONE*:

$6 JIUWU Micro USB Male to USB Female Host OTG Cable + USB Power Cable Y Splitter

http://www.amazon.com/gp/product/B00NSBVNCM?psc=1&redirect=true&ref_=oh_aui_detailpage_o06_s00
USB DAC:

$29 Behringer U-Control UCA202 USB Audio Interface

http://www.amazon.com/gp/product/B000KW2YEI?psc=1&redirect=true&ref_=oh_aui_detailpage_o08_s00
Scosche Tacoma Dash Kit:

$35 Scosche TA2053S9B Compatible with 2009-11 Toyota Tacoma ISO Double DIN Dash Kit, Light Metallic Silver

http://www.amazon.com/gp/product/B002GOFYLS?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00
Joycon EXR Steering Wheel Control:

Joycon EXR Steering Wheel Control PC Interface

http://www.amazon.com/gp/product/B00CHXAV1Q?psc=1&redirect=true&ref_=oh_aui_detailpage_o04_s02
4 Port USB Hub: http://www.amazon.com/gp/product/B00GLJH7V4?psc=1&redirect=true&ref_=oh_aui_detailpage_o04_s02

Not shown are the Cigarette lighter/USB charger converter. Find something at least 2.5A for charging. The tablet, on it's own, needs 1500ma to charge when you're using GPS and the screen is bright. But consider you'll be running a few accessories via USB and they need power too. I opted for a 3A charger to be safe.

The most important piece of this entire puzzle is the custom kernel that Timur developed for the Nexus 7. This is what yields the deep sleep, USB auto-mount, fast charge, and other important capabilities inside the tablet. None of those features come with the device stock and you'll need to root your tablet and flash his kernel first. I think he charges something like $40 for the software. It's worth every penny in my opinion. https://timur.mobi/timurs-kernel-n7-2013/