Android Tablet as Car PC

An android tablet ia a logical choice for a car PC. The device offers additional features beyond regular car stereos. While many car stereos have GPS, the android device offers a more intelligent GPS. It has all of your google contacts addresses already in the GPS, it has your calendar with events and their locations, Chrome to phone can automatically send directions from your computer to your car. The device can store music, use internet radio, or play music using a cloud player such as Amazon cloud. These are features not available on even the most high end luxury cars.

I recommend choosing a tablet that already has a car dock. This dock can be easily modified to be permanently installed where a double din CD player would normally go. Also, with a car dock, the device will be easily removable so you can prevent theft and use the tablet elsewhere.

Tools:
Wire Strippers/Crimpers
Soldering Iron (Recommended)
Screw Drivers
Drill
Dremel with Cutting Blades

Equipment:
Tablet with Car Dock ( I chose Samsung Galaxy Tab 7+)
1/4" Sheet Lexan (Approx 10"x6")
Paint
1-1/4" Hole Saw
3/8" Drill Bit
Amplifier
Car Audio Adapter
Spade Plugs
Wire - Heavy Gauge to Power Amp
Wire - Medium Gauge for Speaker Signals
Grommets
Electrical Tape
Scotch Tape

Step 1: The Audio

Replacing the stock stereo unit with a android tablet requires an external amplifier for the sound to play through the speakers. I choose a 4 channel amplifier. Four channel because my car has four speakers. I have the amplifier mounted under my passengers side seat, but the amp could be mounted just about anywhere.  I chose just about the cheapest amp I could find.  I don't listen to much music, mostly audio books and podcasts, so I was not too concerned with sound quality.  I do listen to music using this amp and it sounds good enough for my ears.

Comments

[Sassah122]

This is good for people who have a lot of time and money on their hands. I did a very simple thing.
1. Get iPhone of android windscreen mount.

2. Use a standard audio cable to transfer audio signals from phone to car. I used aux port but you could also use a special cassette tape that provides a 3.5 mm jack.

3. Connect the phone's usb car charger to my 12 volt output.

4. Download apps and enjoy!

[primo7]

Great idea but has one flaw. There is no android software. In my car I have carpc with software Centrafuse. Centrafuse have handsfree phone option when I make the call or recive the call the music mute
and when I use integrate navigation (Garmin) that when spoken instructions the music mute. It would be great if it would be possible in Android phones and tablets.

[assman66]

Nice write up. Working on my own because i came across this one. One question, how are you using the 4 channels out if the amp has 4 channel inputs? from the looks of it you have 2 channels going in(the 2 rca) to 4 channels out(4 speakers). I have installed amps before but am i missing something here, don't you need 4 channels in to get the 4 channels out?

thanks in advance

[hamsammy]

Great write up! I'm running into the same issue with a build of mine for an ipod cable which goes from dock 30 pin to USB for charging and 1/8" for audio. The audio sounds great until I plug the power portion in and then, NOISE! I haven't been able to figure it out but suspect it's just poor quality shielding within the cable since it's getting clean power from a computer PSU. Did you ever figure yours out?

[willyam111]

I would try adding a ground loop isolator into the circuit.

[lkatrencik]

if you don't have enought room for dock connector you can make your own http://forum.xda-developers.com/showpost.php?p=20710266&postcount=14

(samsung)

[amarshall9]

I never thought about using a tablet for a radio. I rather listen to my android tablet then listen to the radio because the radio plays garbage repeatably.   Does it work wireless like some obd II systems.

[leonthedruid]

Now if only there where an app that let you use an Android tablet as a speaker phone unit for a Bluetooth enabled cell phone.

[orbit1212]

Hey you should definitely make a series of videos on this this is amazing and i will be doing it in my car.../// i want to also integrate some engine stuff such as speed, rpms, if the tablet can read it i want to see if it can google maps integration as well just some ideas

[willyam111]

The Tekzilla recently did a show segment on a cheap bluetooth obdii reader that can transmit to a tablet running Torque to give you those engine parameters. Here is the bluetooth module. I personally have never used it so I can't speak to how well it works but they seemed to like it.

http://www.amazon.com/Soliport-Bluetooth-OBDII-Diagnostic-Scanner/dp/B004KL0I9I/ref=pd_sxp_grid_pt_0_0

[BigMaxee]

Hi Guys, I am very new to this forum and find all this discussion very interesting. I have a 7" Android device which has outlived its usefullness to my children apparently and so I thought it might be fun to rig it up in the car for playing tunes and using as a gps and reversing camera. I noticed that JFarmer had quoted some regulations including the following "(2)In this regulation “television receiving apparatus” means any cathode ray tube carried on a vehicle and on which there can be displayed an image derived from a television broadcast, a recording or a camera or computer." Now correct me if I'm wrong but I am pretty certain none of the devices any of us have or are talking about has a "cathode ray tube". Does this mean that the laws quoted by Mr JFarmer are nul and void perhaps?
Just a thought... many have gotten by on a technicality before. :)

[lordvellos]

Just out of curiosity, but since android is an "open" platform, are there in the market apps or hack that it could trully be converted to the central of the car, attaching it to different sensors to get temperatures, rpm and all other kind of stuff?

[fairwinds88]

Yes you can, and it is a shame that the author did not delve into a vehicle data interface (OBD II). The android market has a host of apps that read in important vehicle data from an OBD-II interface.

You see, all cars from 1996 and later have a standard port underneath the driver's dash that allows for auto shops to run diagnostics on cars and to even set some variables. One of these variables is the state of the "engine light", which is how shops tun it off when their work is complete. Other information available ranges from fuel consumption to o2 sensor readings, practically all of the data that the car's computer has on hand, including those that you mentioned. Sadly, one of thee ones commonly missing is oil pressure.

Anyways, this port can be connected to by an aftermarket reader that uses a decoding chip (one of the most popular is called "ELM 327"). This reader may be connected to your android, ios, or other device, granted that it has the software to read the incoming data. There are many bits of software out there for reading OBD data, my favorite is "Torque" on the android market.

As for connectivity, you could use tethered or wireless. Wireless would be in the form of a wifi hotspot connection or a bluetooth connection. I curently use a wifi OBD-II adapter in my own car with the Torque application. This adapter only cost $25 on Amazon and seems to work perfectly for me (though there seem to be many cheap brand versions that do not work well). I believe that Android supports all communication formats, while iOS devices do not support the data transfer channels in a bluetooth connection.

There's a lot of info that I have not put in here, but I hope this answers your questions. On a side note, my car did not come with an mpg calculator, but Torque works wonderfully at calculating instantaneous, average, and trip mpg.

[Fichtenelch]

And don't forget to install a fuse within the first 30cm of wire from the battery! This is very important to protect the wire and the car.

[bdore]

You could add the 12v power socket with an inline fuse to the remote (power antenna) wire from the wiring harness you bought. That would make things simpler and would not require cutting any stock wires.

[johnvillar]

Didn't know about this ground loop isolator... now i know why i get a lot of static on my rig. Thanks pal.

[skrubol]

Static or alternator whine? Usually in cars it's a whine that changes pitch with the speed of the engine.

[johnvillar]

Definitively whine (mistook the sound for plain static)... its pitch gets louder as i accelerate, so i guess it's because of the alternator spinning more rapidly...

[Trashtermind]

Check your grounds, and check for a fried channel on your amp, happened to my first amp thanks to me dropping it to like 1ohm before I even knew what ohms were, lol.

[WolfTohsaka]

Great instructable !

Just one thingie... when replacing the car stereo, you use a harness to connect to the speakers... why not use a harness to get the (fused) stereo's 12v to power the amp and tablet ?

Kevin

[willyam111]

jdonor got it right. The amp draws a lot of current and you need very thick gauge wire to power it. Connecting to the battery is the best way to do this. Don't forget the inline fuse holder when powering the amp. And be sure to read the instruction manual that came with you amplifier or get it professionally installed if this part scares you.

[lloydrmc]

The harness adapter should power the Tab, and you are right about the amp.

[jdonor]

Having done some car audio mods before, I can tell you that's a bad idea. The problem is the available current due to the wire gauge. The wiring in the car is going to be around 22 gauge, whereas an amp needs something around 8 (at least the ones I've seen). As a cautionary tale: I got a cheap kit to wire my first amp that came with 12 gauge wire for the power, and my amp was fried in a day. I mean: toast. Talked to the experts and they said I needed a bigger gauge. Moved to 8 gauge with the replacement amp and I haven't had a problem since. So you'll definitely want to read the manual for your amplifier, find out what gauge wire you need and power it straight from the battery. Hope that clears it up!

[WolfTohsaka]

If you replace a stock head unit with something like 4x25RMS AB class, you need a 4x25RMS AB class amp to use "dashboard gauge". Anything above stock will require power from battery... granted. BUT, you need a relay using the after-contact from your car stereo if you don't want to let the amp powered when the car has shut down.

[baldmosher]

If by 'noise' you mean electrical interference, have you tried a ferrite loop in the cable to see if that helps? (It might not)

[lloydrmc]

Good idea.

[Kiteman]

This is a cool project, but readers ought to be aware that it is probably illegal in the UK, since it is not a dedicated satnav or music player.

You can get round it by wiring it in so that it cannot function whilst the engine is running.

[lloydrmc]

Figures.

[jfarmer3]

Great project - although there are plenty of bluetooth enabled after market systems available - which could make the audio linking aspect a bit easier.

Saw this regarding legaility in the UK...
http://www.in-carpc.co.uk/legislation.htm
"
Ensuring that the driver is not distracted

Section 109 of the Road Traffic Construction and Use Regulations clearly states what information can legally be displayed on a screen that is within the driver’s field of vision in a moving vehicle. All our fully installed systems apart from the Basic and Lite packages include the Centrafuse software interface, which provides a touchscreen friendly user interface. Centrafuse comprises many modules that perform different functions, examples of which are the navigation module, the hands-free phone module and the DVD player. When the vehicle starts moving, any modules that could cause distracting or illegal information to be displayed on the driver’s screen are automatically disabled. Using the examples above, the DVD module would be disabled but the navigation and hands-free modules would not, as these are both legitimate uses of a driver-visible display.

In addition, Centrafuse is automatically activated whenever the vehicle starts moving, so that it completely blocks the Windows desktop and any other running programs, and can only be minimised again when the vehicle is stationary.

For fully installed systems that do not include Centrafuse we can use other means to ensure that the system remains completely legal.

"

So it looks like centrafuse could be your friend here ... see http://www.centrafuse.com ... and they have a bunch of apps already available to look at car diagnostics etc

This is the law
"
109.—(1) No person shall drive, or cause or permit to be driven, a motor vehicle on a road, if the driver is in such a position as to be able to see, whether directly or by reflection, a television receiving apparatus or other cinematographic apparatus used to display anything other than information—

(a)
about the state of the vehicle or its equipment;

(b)
about the location of the vehicle and the road on which it is located;

(c)
to assist the driver to see the road adjacent to the vehicle; or

(d)
to assist the driver to reach his destination.

(2) In this regulation “television receiving apparatus” means any cathode ray tube carried on a vehicle and on which there can be displayed an image derived from a television broadcast, a recording or a camera or computer.
"

Which means that you could not use it to change your music selection while driving ... but you can use it for a sat nav and to show images from a rear view camera

[beehard44]

Have you tried using a capacitor connected parallel to the + and - of the tablet's 5v in? a 1000uF capacitor should do the trick, the value isn't critical
also you could do the same to the amp but use a higher value capacitor, like 5000uF? Again, it's not critical
also, use shielded wire for any audio signals

[willyam111]

What are you recommending these capacitors for? To reduce noise? The ground loop isolator works well to reduce any noise problems except when I tried that cable in the last step. However, that cable had the power and audio cables running right next to each other with very thin gauge wire. It was the only cable for my tablet I could find like that and was not made by Samsung. If you are saying that the capacitors will reduce the noise with that cable I could give it a try.

[lloydrmc]

If you want to reduce the noise, the value of the cap IS critical. There are small circuits that you put in line with the power that consist of one or more capacitors and one or more chokes e.g. http://www.ebay.com/itm/PAC-CSS-12-CAR-AUDIP-STEREO-12-AMP-ALTERNATOR-IGNITION-NOISE-FILTER-CHOKE-/130668860196?pt=LH_DefaultDomain_0&hash=item1e6c789324

I can see how the ground loop isolator could help, and my search for "car stereo noise filter" yielded some of those, too.

The noise could be - at least in part - due to noise being picked up because of poor shielding on the signal (not power) wiring. It might actually be worth getting a higher-quality interconnect, such as one from Monster. One at least hopes these would be better shielded, and less noise prone.

Don't put any caps on your signal cable - it will serve only to distort the sound.

[CyberBlade]

Concerning the whine:
I used to connect my PocketPC's power adapter to a small filter-like device, which was between the car battery and the power adapter. This device came along with my old Car CD Player.

Worked great. Whine without it, and noise free with it :)

[BSWill]

Okay, this project is exactly where everyone is going to go to, either by performing this project now or by purchasing their transportation with this capability already made stock by the manufacturer sometime in the near future.
The thing that is mentally twisting me up right now is the upcoming availability of the "New IPAD" (IPAD 3). Short of finding a comparable car dock for the thing, the New IPAD appears to have incredible advantages over the upcoming Samsung, (at least when using it outside of the vehicle), but the fact that it is an IOS system and not Android is concerning - especially when considering linking to my 2000 F350 SD, (7.3L Diesel) OBDII vehicle's computer diagnostic system.

1. Will I have trouble finding a system comparable to the kiwi (http://www.plxkiwi.com/kiwibluetooth/buynow_torque.html) introduced below, which appeals greatly to me as I see it here?  Other alternatives?

2. Are there other drawbacks to Apple's IOS rather than Android for this application?

What are all of your thoughts as the New IPAD really appeals to me and purchasing both tablets is just ridiculous?

[willyam111]

1. I don't think you should. I have seen lots of OBD2 bluetooth transmitters. The transmitter you show just sumbits the OBD2 data over bluetooth. After a quick glance at Google there seem to be quite a few apps to display OBD2 data that is transmitted during bluetooth. I don't have a bluetooth ODB2 adapter or a modern iOs device so I can't confirm any of this but somebody else may be able to comment on this.

2. Android has Google Navigation integrated into the os. When an address is in an email, contact , or calendar event it can be clicked and brought up in Google Navigation. This is very nice and quick. The other ability of Android is background apps. I can listen to a podcast, audiobook, or music with Google Navigation in the foreground. When the app wants to tell me to turn it mutes the background audio. I can also do this with the audio app in the foreground and the GPS will still mute the music. I don't know how well this works on iOs.

There is virtually no support for Android tablets. Samsung releases new tablets faster than they can support them. The tablet I have shuts off randomly, I can't write to the SD card without rooting it, and the wifi won't work with my router. The tablet I have is riddled with problems and Samsung's solution is to release more tablets. Honeycomb is a mess. Google knows it and that is why they won't release the source code. Android developers have given up and are waiting on ICS. Android tablets are not yet ready for prime time. Because a tablet's input and options are so simplified, it is imperative tablets work right all the time. That is what an iPad is good at. However, the Samsung is the right size, has Google Navigation, and Samsung makes a car dock; the software for it is just buggy and not yet ready. It is really up to what you value more.

[Beergnome]

Another thing that could add extra functionality and general Awesomeness to this project would be include something like this:
http://www.plxkiwi.com/kiwibluetooth/buynow_torque.html to the over all project so you could also monitor the vehicle's performance itself rather than it just being for navigation and Mulit-media playback

[willyam111]

I definitely agree. The other option I am looking into is a android app that can start the car via bluetooth. I know there is an instructable on doing this. This way I could have a passcode to unlock the tablet and then press a button to start the car. Very reminiscent of the movie The Transporter.

[noel0leon]

Hi, Could you charge the tablet via the power cable for the stereo which has been replaced?

[willyam111]

You could probably splice that female cigarette outlet into just about any power cable. However, the best way to do it is to add your own fused circuit. For one, you aren't cutting any factory wiring which is nice. You also know exactly what is being powered and can choose a fuse accordingly. You need to wire in the female 12 vdc socket however. Don't splice the power cord directly. This can fry the tablet.

[Shadow351]

You could also try a ground loop isolator.

http://www.amazon.com/Stinger-SGN20-Ground-Loop-Isolator/dp/B002ZRQ3PW/ref=sr_1_2?ie=UTF8&qid=1330990473&sr=8-2