October - December 2014
I have installed an Android tablet computer into my car center console. Tablet is connected to a car audio system through car's stock stereo system. Car diagnostic informations are available through OBDII interface.
7" tablet fits perfectly into a double DIN car radio space. My car, Peugeot 307, has non-standard front center console stereo opening so an enclosure is needed. I got one of eBay for $17. Two buttons are installed on enclosure, power button for car stereo and the power button for the tablet. Buttons are glued from the inside of the enclosure. Backside case of tablet is removed, and tablet is glued and fixed with screws into an enclosure. As audio output connector is on the side of the tablet, audio cable would stick out on the enclosure, so an extra audio output connector is soldered onto a tablet pcb, facing to the the back of tablet. Same thing is with the power connector, so an USB cable is soldered to it. Power button from enclosure is soldered to a power button on a tablet pcb.
Stereo is integrated into a car and it doesn't have its own display. Instead all informations are displayed on a car center screen, which suits me great, because the stereo can stay in car to provide FM radio and audio amplification. Stereo front panel is removed so stereo can be fitted deeper into a center console, behind the tablet. Also a CD player mechanism is removed from stereo. All needed car stereo controls are available on the steering wheel, except the power button. So a power button is wired to one of the buttons on the enclosure. Stereo doesn't have an auxilary audio input, so I made one by soldering audio connector directly onto the audio amplifier. Instructions for the particular stereo can be found here. When the car is running, amplifier is powered at all times, even when the stereo is off, so tablet has an audio output at all times. Humming and noise was present, caused by the ground loop between car stereo and tablet, so an audio insulator was added. Ground loop occurs when two devices have different ground potential, causing an equalizing current to flow between them through, in this case, an audio connection. A 12 to 5V USB car adapter is soldered to stereo power supply. It provides power to the tablet and the external bluetooth GPS module.
Tablet doesn't have a GPS receiver, so a external bluetooth GPS receiver is used. It is a Royaltek BT GPS receiver. And for car diagnostic information, ELM327 bluetooth OBDII adapter is used. Car stereo is pushed a few centimeters inside center console to make room for the tablet, and tablet with enclosure is mounted into a console.
In the following showcase video car diagnostic informations are available using application called Torque Pro (OBD 2 & Car). Navigation application is OsmAnd Maps & Navigation. For navigation app to be able to use external GPS bluetooth receiver, Bluetooth GPS application is needed. The music player application is MortPlayer Music.
I have also planned to install an USB web camera as a rear view camera, but I dropped that idea for the time being. I couldn't find an android application that would show the video from the web camera that I had. Maybe I'll try it again some day.
Feel free to comment the project, and have a nice day.