After the successful installation of the raspberry pi 3 based rear entertainment system in my Odyssey I decided to expand the idea and test the flexibility of the hardware mix I'd put together as part 2 of my mobile entertainment trilogy.
Here are the specs and planned features for the install:
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Mirrored audio and video via two aftermarket LCD headrests where audio and video are handled at each monitor independent of the car's stereo system. Additionally the aftermarket headrests support IR headphones as a future option.
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An intelligent power supply that can survive the hazards of the automotive electrical system. Namely one that can resist load dump conditions and keep supplying power to the pi during temporary power cuts / brownouts (I.E., cranking car). Additionally it needs to be able to start the Pi when the key is switched to ACC/ON and shutdown the Pi gracefully when the car is shut off.
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An easy to use front end that can be remote controlled via a RF remote OR Android / IOS devices via wifi. The idea being that small children can't operate a standard remote, therefore the parents will have the option to control movies from the front of the vehicle.
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Local storage support
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Resuming options for automatically restarting video from the last time the car was shut off.
Wiring Diagram:
Only meant to paint the broad strokes of the installation so understand that it is not completely comprehensive. For example the chassis grounds and the AV grounds aren't shown for the sake of simplicity.
Note: The Raspberry Pi's composite Video Out is handled with a 3.5mm to AV RCA cable and only the video is used. The audio output from the SYBA sound card uses a seperate 3.5mm to audio RCA. Both are combined to form a complete signal set which is spit out to each of the headrest monitors. The reason the Raspbery Pi's built-in audio isn't used is because the SYBA output is much cleaner and isn't PWM based, therefore it can be amplified in Kodi to make up for the losses in the barely active headrest monitors.
BOM:
Here's what I used to build the system:
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A SSD (preferably) 2.5" Hard Drive. The only important thing to consider is choosing a hard drive with a low current draw since power hogs will trip the Raspberry Pi which serves as its power supply. Aim for < 0.4A draw.
Software, Installation, and Configuration
See instructions above for my Odyssey build. The Sentra was identical in this regard.
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Hardware Assembly and Installation
Using the diagram above, the assembly is pretty straight forward. For the details of the LiFePO4wered/Pi3 installation and its related enclosure, see their respective manuals. The wiring is a simple or as complicated as you make it usually rooted in how neat you want your installation. Some important notes specific to the Sentra:
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Add-a-fuse may seem like a sloppy solution here, but it works well in this particular instance. The Sentra's J/B fuseblock in the kickpanel has multiple strong constant and switched supplies coming to it as well as multiple unallocated output slots for fuses. On the output legs of each unoccupied of the fuse holders there is no wiring, so using an add-a-fuse effectively pulls from the larger supply to the entire fuse block All it takes is a meter to determine what's constant and switched 12V and you can plug the add-a-fuse into whatever works best.
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The Drok DC to DC convertor is adjustable. Its very much a double edged sword because you can't just plug it up and go. You absolutely have to adjust it with output feedback (multimeter) to make sure it's outputting 5VDC while your car is running before you get it anywhere near the Pi. Then and only then can you use it to supply power to the LiFePO4wered/Pi3.
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Pictures Coming Soon
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Final Results - Coming Soon
Similar to the Odyssey install this setup has survived toddler abuse for 3+ months now without a hitch.
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