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Car computer/car stereo

Mon Oct 20, 2014 3:09 pm

Hello, this is my first post on this forum. I haven't used or bought a Raspberry Pi, but I am familiar with the possibilities and I've already had some experience with Arduino from some of my University's classes.

Project Introduction

I've seen some projects on the Internet about car media systems using a Raspberry Pi and I was thinking: I could make something like that for my own car. My idea is to let the Pi take over the function of the car stereo (including some additional features), while using/maintaining the space a standard car stereo uses. So I am not thinking about most of the “car computer” projects I've seen so far, as they are an addition to the car stereo.

The “additional features” I am talking about:
  • GPS navigation
  • Digital storage of all of my music
  • Possibility to play music from smart phone (probably via Blue-tooth)
  • Eventually I would like to see some of the OBD-information (On Board Diagnostics) on the screen, although that has a lower priority.
  • And maybe more.
The reasons/motivations for this project:
  • The current car stereo doesn't allow me to play music from my phone as it has no Blue-tooth or 3.5mm audio-jack connection.
  • The current car stereo doesn't have a navigation system. Although it isn't a problem to use a separate navigation system, it would be less hassle and safer to have an in-build navigation. Less hassle because there are no separate parts to forget or break, and safer because the separate navigation system is always attached to the inside of the windscreen, taking a fair amount of visibility away.
  • Buying a new stereo for my car will cost a lot more money than “building your own” and apart from that there aren't many car stereo's that fit most of my requirements, while still maintaining to the single din layout that fits my car. Unless you talk about those retractable flip-up screens, but those take away the possibility to reach about half the buttons on the center-console, including the hazard-light button.
  • I hate to have most of my cd-collection lying in the car and being exposed to high/low temperatures, sunlight, robbery, etc.
  • As an Automotive Engineering student I am interested in my vehicles information, and it would be extremely awesome to see live OBD-information while driving (without having my enormous 17” gaming-laptop on the passenger seat).
So in conclusion I am thinking of building a car stereo with navigation, a music library, bluetooth connection, live OBD and maybe more, which will be inserted in the original stereo's single din space.

There are some questions I have, that maybe somebody here can help answering/figuring out. They are marked in red.

Thanks in advance for any help/interest in the project.


1. Raspberry Pi
First of all of course there is the RPi, I thought it would be best to just start with an RPi B+.

2. Touchscreen

As this project is based on a single din radio, the largest screen possible is probably a 3.5” screen. As a keyboard/mouse in the car is not really what I want, I am looking into touchscreens. I've seen numerous 3.5” touchscreens. Can somebody tell me the probability (and difficulty) of getting these setups to work:


(as I couldn't copy a table into the text here, I made a screenshot. the links below are in the same order as the table)

1. PiTFT
2. Neosec Display
3. Arduino-based Display
4.1 Display with Touch Panel
4.2 Touch Panel Driver

Note: the price of the PiTFT is different than the added link, because I would order that via Adafruit's distibutor in the Netherlands, instead of via Adafruit itself.

The PiTFT (setup 1) and the Neosec (setup 2) both are probably easier/faster in getting working than the other setups. But the higher prices concern me, is it worth the price difference?

Is it possible/complicated to get setup 3 (with an PCB adapter for Arduino) working on a Raspberry instead of an Arduino?

I've seen this thread on this forum, setup 4 is based on the setup/idea used in that thread. With the difference that the display I listed is connected in an other way than the display in the thread. Again the question if it is possible/complicated to get this setup working on a Raspberry?

Are there any interesting alternatives that I haven't heard of?

3. GPS Navigation
For the navigation a GPS signal is needed, which my car doesn't have. I've found a GPS-module with antenna, which should take care of that. But I haven't found anything about the use of this GPS-module with a RPi. Can somebody say anything about using this module with a RPi? Apart from that I am wondering if the antenna could be placed inside the stereo space (and still maintain a good GPS connection), or that the antenna should be placed somewhere else for a better GPS connection.

4. Media player
I am thinking about playing music in all of the following ways:
  • FLAC files from an in-built USB-stick
  • The standard radio (FM) signal
  • Music from my mobile phone (via Bluetooth)
In this case I think a 512GB USB-stick will have enough space to store all of my CD's, as I understand that FLAC-files usually use about half of the space a CD uses. So around 350Mb of FLAC-files per CD, which roughly means about 1400 CD's on a 512GB USB-stick. I don't come near that number of CD's, probably around 100-200. But as I was thinking of using the USB-stick as an in-built memory for other things (like the maps the navigation software uses), I am sure 512GB will be enough.

For the FM-signal I was thinking about using a FM-module and just connect it to the existing car antenna, as I've seen more people implement those FM-modules.

And for the music from my mobile phone I was thinking of using a bluetooth dongle.

The sound quality of the analog output of the RPi is said to be not great. I don't know much about sound, amplifiers, etc. and I am not an audiophile, but I would like to at least have the same sound quality as the standard car stereo now has. Would using an amplifier with the 3.5mm sound output of the RPi give me the sound I want or should I be better of looking at other sound output possibilities like a Behringer UCA? I've seen multiple tips on the internet about using those Behringer UCA's as RPi sound outputs, are they really worth the extra money compared to just using the RPi's analog sound output?

And regarding the amplifier: the standard stereo has a 4x45W amplifier. I thought I had found a nice amplifier that also had 4x45W output, but that one is powered by 12V AC, while a car battery puts out 12V DC. So it is probably easier to look for another amplifier. As I don't really know what to look for, are there any tips on what amplifiers I could/should use? Could I for example use a 4x25W amplifier (as I see some standard car stereo's use them as well) or amplifiers with any other output, or could that give any problems/poorer sound? Is there a minimum required sound output? And are there other factors to think about?

5. OBDII data
For the OBD data I was thinking of using a bluetooth OBDII scanner, as they use less space than scanners with USB-connection, I am already planning on using a bluetooth dongle (for the connection with my mobile phone) and a bluetooth version makes sure there is no need to place a USB cable between the OBDII-connection and the RPi.

6. Casing

As the idea is to replace the standard car stereo with the RPi, I am planning on placing the RPi and all of the hardware components in the same space a standard single din stereo uses. I am thinking of getting an old car stereo with the standardized connection in the back and just take out all the hardware inside and place the RPi and new hardware inside. The standard car stereo connection will be used to connect the power to the components, the sound to the speakers, the antenna th the FM-module, etc. The screen, an “external” USB connection and probably some buttons to navigate quickly through the different software (GPS, Mediaplayer, OBD, etc.) will be placed together with a self designed front on that old stereo casing. So when the project is finished it should be a real plug and play car stereo.As almost all components are very little and don't use much space, there will probably be no problem there. But can I expect problems or should I take precautions regarding the heat that comes of the RPi or some of the components?

7. Power Supply
For powering the RPi I am planning on using a standard USB car charger, and stripping it of its casing to use it inside the stereo casing. The power will then be going from the power pin on the casing connector to the USB charger, delivering 5V, 2.1A via USB to the RPi. Because I am planning on using a number of different components together with the RPi, if necessary I will use two USB chargers, to power other components without cutting to much of the RPi's power.

There is only one problem with the power supply: As you turn off a cars ignition, it immediately cuts power to the stereo. As that is probably not a good idea for a RPi, the RPi needs to get enough time to properly shut down. I've seen a solution for that problem, but they are sold out and rather expensive (as they push the total cost of the project up with roughly 10 to 20%). Are there any cheap alternatives (possibly DIY)?


As I don't have an RPi at this moment, I can't say much about the software/OS and I haven't looked deep into this. I don't have many requirements for the software/OS, except that it supports the different applications I want to use and it can cycle between them. Are there any interesting programs or operating systems that I should be aware of?

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Re: Car computer/car stereo

Mon Oct 20, 2014 3:19 pm

I roughed out a solution to the power problem here: http://www.soronlin.org.uk/power-switch It would require a bit of reworking to apply to the car ignition rather than a switch but that would be straightforward. Also there are probably no such things as relays that work on 5mA, so you'd need to either replace R2 with a FET or use a darlington driver. The latter is probably simpler.

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Re: Car computer/car stereo

Fri Oct 31, 2014 6:39 pm

Media Player - Output: Wolfson Audio Card
http://www.element14.com/community/comm ... wolfson_pi

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Re: Car computer/car stereo

Fri Oct 31, 2014 8:15 pm

HuPro wrote:Media Player - Output: Wolfson Audio Card
http://www.element14.com/community/comm ... wolfson_pi
That may not be suitable, the Wolfson card only works with a Raspberry Pi model B. It won't fit a B+.
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Re: Car computer/car stereo

Sat Sep 12, 2015 8:06 pm

Did you ever find a solution for this? I am currently trying to do something similar, and I've only found instructions online for using the pi in conjunction with your car stereo instead of completely replacing it.

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Re: Car computer/car stereo

Sun Sep 13, 2015 9:25 pm

Unfortunately not. As a student with a lot of hobbies, I'm on a tight budget and I haven't had the spare money to even buy a RPi. So I since then didn't look further into the subject. I still want to try this project, but I have other priorities right now.

Good luck with your project, I am very interested.

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Re: Car computer/car stereo

Mon Oct 19, 2015 8:48 pm

Hi guys!

Happy to see i'm not the only one with that kind of idea!

I'm thinking about creating the same kind of device you thought about, but with a 7inches touch screen display that would fold into the single din spot to be able to hide everything when not in use..

Hope we'll be able to figure out something together! :)


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Re: Car computer/car stereo

Mon Oct 26, 2015 9:35 pm

Hi guys,

I have almost the same project ...

and of course I have almost the same problems...to me, the most problematic topics are:

*start-up/shutdown connected with the car ignition - I did some research and there's this mausberry project and the guys sales the board for around 20-25$ each, but the one I ordered one month ago, I haven't received yet, so I doubt that the project is still active.

*OS based on Android or Ubuntu Touch - that's a pain in the neck cos I don't want an OS which is windows based... for the car, I prefer a phone/tablet OS which can be easily controlled by a touchscreen. The only straight-forward Android installation installs Android 4.X.X and it boots extremely slow. I tried to build my own android (after a few days I succeeded) but the bloody fastboot mode was a problem. I can't set empty raspberry pi into fastboot mode. Ubuntu Touch is quite similar, because it is based on Android system image.

*GPS receiver - I found one module from this website https://www.kiwi-electronics.nl/raspberry-pi and seems to be quite promising, but I haven't bought it yet

P.S. I was initially planning to build the whole infotainment system, but I realized that my VW Golf 6 has decent audio system, the radio is fine, therefore I decided to save some money and use the AUX to connect the audio signal from the Pi to the amp of the car.

If you have some good ideas about the topics I mentioned before, I would be grateful if you share it.

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Re: Car computer/car stereo

Sun Aug 07, 2016 5:24 pm


I'm looking into doing a similar project myself.. Did anyone ever get anywhere with this?

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Re: Car computer/car stereo

Mon Aug 08, 2016 8:40 am

gkgeorgiev wrote:start-up/shutdown connected with the car ignition - I did some research and there's this mausberry project and the guys sales the board for around 20-25$ each, but the one I ordered one month ago, I haven't received yet, so I doubt that the project is still active.
In a car you've got an advantage over most similar projects because you can always have power. The only non-trivial part is switching it off.

So get yourself a 12V relay and a small Pi relay board.

It works like this: The main power to the Pi comes un-switched from the battery. There are then two relays that can power the Pi from it, wired in parallel. The first is controlled from the switched battery power, so it's only on when the ignition is on. The second is controlled by the Pi via a GPIO pin. Then the switched battery power also switches a signal into another GPIO pin (using a second set of contacts on the same relay.)

It's a bad idea to feed the battery power through a voltage divider into the PI because, if the battery terminals are loose, there can be up to 300V spikes on those wires. Switch the Pi's own 3.3V instead.

When the ignition is switched on, the Pi gets power through the first relay. One of the first things it does is to switch on the second relay. Now when ignition is off the Pi is still being powered through the second relay. A background process is monitoring the state of the ignition via the second GPIO pin and when that goes away it does a graceful shutdown and switches off the second relay.

It may also be necessary to run the power directly from the battery on a dedicated pair of wires. Otherwise the voltage may drop too low when the starter motor is running.

Liam Antony
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Re: Car computer/car stereo

Sun Feb 26, 2017 7:45 pm

If you want to have great car stereo , I strongly advice Kenwood . Kenwood is one of the leading manufacturers of car audio equipment and they have earned a great reputation for making reliable and very good functioning car touch screen stereo systems. I have KENWOOD DDX770 and it has great functions . The quality in this product starts with the big 7 inch crystal clear touch screen display it features. This is larger than most of the units. It also acts as an am/fm Bluetooth receiver and it can receive CD’s and DVD’s too.
it came with a backup camera that automatically turned on and displayed when you put your vehicle in reverse. That was a very nice touch. Another very good feature is the display off button. If you hold the mute button down it will turn off the lights on the display yet leave everything working. http://www.caroutfitter.com/best-touch- ... o-reviews/ has great and informational reviews about car audio systems

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Re: Car computer/car stereo

Tue Feb 28, 2017 2:29 pm

Hi guys I realized the same project last year, I'm using raspberry pi as bluetooth reciver for car stereo as navigation sistem and also as a media player with KODI. I connect raspberry pi to cigarette lighter for the power supply and to a small LCD monitor to visualize the raspberry pi (my car is a bit old and I didn't have any computer on board). I resolve all my problem and now my car have bluetooth, navigation system and a full media player to do everything that I want. If you are interessed visit my page at http://projectrspi.weebly.com/hcp.html I write all that I did and in a few week I will pubblish the .iso file with all configuration and all repository and program installed.
I made a site with a raspi projects' collection, my idea is sharing my projects with other person.
My web site is https://raspiproject.altervista.org/ I hope you like it and you want work with me

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