Carputer – 7″ Touch Screen Android

This is a 7″ Touch Screen Android Carputer with super accurate USB GPS, Bluetooth 4, 3.5MM Audio in/out, WiFi, and an adjustable magnetic screen.  A sketchup file is available for additional customization and resizing as needed at https://www.thingiverse.com/thing:2720349As an IT Field service tech of 28 years, I built this unit out of necessity to replace the smaller screen of the phone, and to provide more utility while on the road. There are pre-built units that you can certainly purchase to accomplish the same task, but I already had the ODROID-XU4 and Vu7 Screen from another project, so I opted to re-purpose them in something that would get more utilization.

Please be aware that some of the following apps/features are illegal to use while driving.  You cannot use apps that allow you to type while you operate a motor vehicle in most states. Check your local laws and do not violate them in your use of this device.  I am not responsible for improper use or application of this device in violation of the law.  This device release is for educational/tinkering only.  Pull over, stop safely, then use it. I am typically in a parking lot before or after a service call when using this device, or I stop and get safe, then do what I need to do.  Be smart in using this device, and don’t get yourself killed over what is essentially a nerd toy with some business applications.

This carputer project is an inexpensive way to modernize your vehicle
This carputer project is an inexpensive way to modernize your vehicle

GPS

The USB GPS Units are way more responsive and accurate than the ones in your phone. This is a huge time saver, as it allows me to better anticipate my turns and avoid waiting at extra lights and making U-turns. It also instantly locates satellites with no waiting.

RepairShopr dispatch portal

I use this calendar/portal to see my appointments in real time, and to pull up the customer’s address for quick-queue of GPS trips. Zero typing and zero talking to Google.  With a Bluetooth RII keyboard, I can also sit and make site notes in the privacy of my truck, while listening to my news or music.

Music streaming

I use Spotify, Pandora, and a multitude of other free music services to provide my truck with sound. These all integrate well into the setup and allow for controls from other programs, as well as the the hard buttons on the car stereo head-unit.

Command Center

The command center includes a digital speedometer (GPS), app wheel, date, time, weather, audio controls, and even an audio visualizer, which is all possible through Car Launcher Pro.

WAZE

WAZE is a speed-trap, cop, and accident finder with real time traffic information, alternative GPS to Google Maps, and much more. This even shows you the posted speed limits to a pretty good degree of accuracy, although it’s not always right, so keep an eye on the street signs.

Torque PRO

You can pair Torque PRO together with an ELM327 or similar Bluetooth OBD-II scanner and you end up with a real time engine information system. It features a full spectrum of digital gauges that are customizable into many different configurations. For cars with or without Turbo, there are boost and vacuum gauges, acceleration gauges, and it even reads engine codes for most OBD-II cars  and trucks. There are other apps out there that do this, but Torque Pro, which is a paid app, works perfectly for my needs. It is nice and stable on the ODROID-XU4 Android images.

WiFi boundary testing and ranging

WiFi testing a large property for wireless coverage, like an apartment complex or hotel, can be tedious if you have to walk it. WiFi Analyzer is a great utility that provides an audible ping for WiFi strength.  It allows you to drive a property and map the WiFi boundaries quickly onto the site plan, exposing coverage gaps with ease, all from the comfort of your AC, which is great when you are down here in sunny Florida.  This tool allows me to stay online 24 hours a day with something a lot more useful than a tiny phone screen. Whenever my phone is near, my hotspot connects up and I’m all set.

Additional Uses

  • Digital LED signage, using Neopixels and a decent battery setup to run them
  • Custom LED, neon, and other lighting controls for effects and show lighting
  • Custom fuel system Interface and No2 controls
  • Private investigator/Detective vehicle and GPS tracking interface for investigations
  • Backup camera or dash cam
  • Vehicle deployable FPV drone base station for site/building inspections and security
  • Rear headrest movies/video gaming system for entertainment of passengers and children
  • EV charge reporting and electric motor, AC, regenerative, and other controls

Components

Uses a combination of M2 and M3 hardware. I also had a few small coarse thread screws laying around from another project, similar in size to coarse thread M2. But you should be able to see what is needed from the hole sizes.

Upcoming features

Auto On/Off with vehicle ignition: Unfortunately, I have not had enough time nor the desire to work this circuit out and implement it into the design. Anyone who wants to can certainly customize one up and show us how it’s done!

Hard buttons / Joystick control: I was considering using a thumb stick with a push button for hard controls, but couldn’t decide where to place such a thing.

Double Din, fully independent version with built in 4-channel amp,and  line-in/out: Clamping system added, for easier mounting into the DIN pocket.  The combination of a wedge fit and screws at the moment makes taking in and out difficult.

Sound reactive lighting controls or HAT: This would really set this device off from the other stuff out there. No off-the-shelf Android head unit can currently do this without additional components. A HAT would allow the Xu4 to be a true custom car command center.

Printing

Use ABS or PETG for best results. Expect warping, working at the extreme edges of your print surface, and layer separation issues. A heated enclosure works well. Use cardboard, corkboard, tin foil, and a heat lamp or track lights; just watch for heat and don’t leave it unattended.

Carputer - Figure 1 - Case for screen
Carputer case for screen

Carputer - Figure 2 - Side view of computer enclosure
Side view of computer enclosure

Carputer - Figure 3 - Back view of computer enclosure
Back view of computer enclosure

Post-Printing Assembly

After printing the parts, install the eMMC into the ODROID and install your Android OS.  Do a dry run without installing the unit into your vehicle and make sure everything is working correctly.  I strongly recommend running the unit for several hours to ensure there are no heat issues with your power supply.

Carputer - Figure 4 - Screen fitted to computer enclosure
Screen fitted to computer enclosure

DROK supply for me was best when set to about 5.7v.  The VU7 is known to slightly flicker when the XU4 is working hard due to current drop across the 5v rail. The power gub tries to fix this, but you gotta turn up the juice a bit. 5.7 was my “sweet spot” for the least amount of flickering.

The setup works the CPUs very heavily!  Warm them all the way up and put the XU4 under as much load as possible. Benchmarking programs work well for this. You don’t want a fire in your dashboard.  If any components feel too hot to hold in your hand, they are running far too hot to put into an enclosed dashboard, which means you need to add ventilation fans.

Carputer - Figure 5 - Dashboard opening
Dashboard opening

Find spots for the USB hub and power that do not come into contact with a chassis ground, or you could have issues with shorts. Make sure all items are properly enclosed with enough venting to protect the electronics.  The Din body screws into the surround, or can be used with threaded set tabs and tightened into place that way.

Having a line out to an AUX or other source is still an issue on this project. I am still looking for a clean AUX out for the ODROID-XU4 while its connected to automotive 12 volts.  For the moment, the unit only provides clean audio via Bluetooth to your existing head unit in your vehicle.

Some have suggested to try the line-out 3.5mm jack on the Boombonnet, and just leaving the little speakers off of it entirely.  Being I2S, it may not suffer from as much noise. The power supply I used here injected 50% noise into the audio signal, making it totally unusable.

Carputer - Figure 6 - Carputer fitted into dashboard
Carputer fitted into dashboard

Noise and ground loop filters cut out bass frequencies and other frequencies, and distort the sound on any system using an amplifier and subwoofer. Trust me. I tried them all. None of them sounded good after being placed inline. The noise was gone, but so were 50% of my sound frequencies.

Additional considerations

Make sure to use care when using Neodymium magnets in any project. They are known for coming together and shattering, causing sharp metal to fly off at high speeds, possibly blinding the user, so be careful!  Make sure your magnets are faced the correct way before gluing them into final position, or you will be prying them out and likely shattering them in the process.

Every single attempt to print this in PLA ended in failure within a few days. It was becoming warped in the car due to being inside the hot dashboard.  Don’t bother trying it; it won’t work.

To print the components, and for further details, please visit the original article at https://www.thingiverse.com/thing:2720349.

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