Here's what I've done.
1. Added MPG calculation to my ELM327 and CarHUD code
2. Broke the flex cable on the 3.5in LCD monitor
The MPG calculation is pretty awesome, I've been able to test it out in the Subaru and it works well. I like this feature since the car doesn't display this information for me.
The LCD flex cable breaking was slightly annoying, but it was a cheap display I got off of eBay. I spent a while thinking of what display to get, 3.5in was always a little too big for what I really wanted. Adafruit sells a 1.5in display, but it's over $50 and that's way more than I want to spend.
Then I remembered little portable LCD TV's from when I was younger.
These things won't work anymore because the US switched to digital broadcast, so the all analog portable TV's should be cheap on eBay. Turns out, I was partly right. Found a Casio EV-500 that has an AV input port, since I'll need that to connect the Raspberry PI to the display.
It didn't come with the AV cable, so I bought one of those on eBay yesterday and not more than 20 minutes after buying it, I found a similar cable in my stash of random crap. Doesn't hurt to have an extra. Tested the TV on batteries connected to the CarHUD system running debug code so it doesn't have to be attached to the car and the AV input works. The display isn't showing the right color, but I can hopefully remedy that.
The TV runs at 6V, so I do have to modify the power supply a bit for the CarHUD system, but that's simple.
This morning I decided to disassemble the TV and figure out how much of a pain it is going to be to strip out the LCD backlight. Much to my surprise, the backlight is a completely separate component! This is super exciting as I don't have to carefully disassemble the LCD and backlight system.
