There are plenty of aftermarket head units one can install, but where’s the fun in that? I’m also a big fan of tactile controls and those are getting harder and harder to find.
There are a few general problems to solve (so far):
- Clean Shutdowns: When using a Raspberry Pi, you can’t just kill the power to it – it must shutdown cleanly. Failure to do that means you might have to run some commands to repair the filesystem, and at worst – a corrupt file system completely. It’s too much of a risk for something that needs to be reliable.
- Raspberry Pi Complexities: As much as the Pi has onboard already, it’s not a slam dunk. SD Cards are unbearably slow and unreliable. The last thing we want is a dead card making our head unit useless! SSDs are the way to go here, but they take up a USB slot – not that we’ll have enough anyway – so we’ll need a hub to add on. Oh, and we’ll need a powered hub to boot, to keep things stable. We’ll also need a strong and stable 5V power source for it all.
- Audio Noise: This particular vehicle has an “upgraded” JBL Audio system, and uses a digital signal from the head unit. This means I can’t send audio easily to the amplifier, because I don’t know what the format is. I’ll probably upgrade the amplifier while I’m a it, so I’m not going to bother to find out. The problem is that the wires from the head unit to the amplifier were intended for digital signals, and become too electrically noisy to run audio over.
- Electrical System Noise: The nominal voltage of a typical car’s electrical system is 12 volts, but it can be as high as 14 volts (the charging voltage of your car battery), and starting the car can causes spikes of dozens of volts.
- AUX Input: It’d be nice to keep this if possible. I will use a hardware equalizer that has a switchable input, but it’s a manual switch. This problem will become even more complex when I add a HAM or CB radio.
- Offline Power: Wouldn’t it be nice to be able to run things without needing the car to be on? Case in point, we were on the ferry recently and it’s too risky to run down your battery.
- Aesthetics: I’m an engineer, not an artist. Things are going to get messy.
I don’t have solutions for everything yet, but I’ll try to add more as I go along.
System Diagram
Here’s how the system should look, if all goes well:
As with all projects, I’m sure things will evolve and change over time so this plan is likely to change!