CarHUD Update, Now only 5 Months after the last one

Where have I been?  I got sidetracked with the CHIP I got from Kickstarter.  That little computer is a lot of fun.

But I have made progress on the CarHUD.  Quite a lot in fact.

As I last wrote, I gave up on the LCD projector idea and moved over to a dual 4 digit 7 segment LED array from Adafruit.

I also acquired 2 Pi Zero's since I last updated the blog.

You can probably see where this is going.

I decided to swap out the Model B Rev1 with the new Pi Zero.  This was done in an effort to make everything more compact.  I also didn't like how I had soldered the OBD-II board to my prototyping PCB.

First I did some testing.

These 3 were done to try and figure out how to get the data to project to the windscreen of the car. (done with the old Model B Rev1 and a breadboard setup).

Then I desoldered a bunch of stuff and re-soldered everything back into a new setup for the Pi Zero.

Then I did some more testing.

This is a bench test of the Pi Zero setup without the GPIO buttons for mode and brightness changing.

 This is a full up, in car test, getting data from the OBD-II port.

Now you're probably saying to yourself, what about the OS?  When I thought about using the Pi Zero in the CarHUD setup, it was about 2 months ago.  I tried running my Yocto build of CarHUD OS on it, and it failed miserably.  So I tried building it with my checkout of Poky's Dora branch.  Still didn't work.

Fast forward a month and I search again for Yocto on the Pi Zero.  This time, I'm successful.  I come across this link: http://www.jumpnowtek.com/rpi/Raspberry-Pi-Systems-with-Yocto.html.

Basically it's the normal guide, but updated with awesomeness.  So what do I do?  I fork his meta-rpi branch into something I customized for the CarHUD.  It's here: https://github.com/xtacocorex/meta-rpi.

pycarhud and pyelm327 are still alive and well on BitBucket.  I pushed commits to pycarhud today as I got more stuff working.  meta-carhud is probably going the way of the ghost.

I'll end with a couple of links to the system working:
https://www.youtube.com/watch?v=LmRZrQ55Ob8
and
https://www.youtube.com/watch?v=eOhZsKN1oYw

Things Never Go As Planned

Since I last posted, I've been working on the LCD projector for the CarHUD system.  And then I stopped.

Here is the story of what happened.

In a first test of the LCD in the Car, I hooked it up to the Raspberry Pi and just had sunlight be the backlight of the LCD.

The display was nicely powered from the CarHUD system, the sun was working as a backlight, but there was one issue: the display text was not green, it shifted to black.  Figuring it was an EMI (electromagnetic interference) issue, I decided to do some research to see if there was any information on unprotected LCD panels.  I didn't find any, but my search wasn't that exhaustive.

In an effort to possibly prevent any EMI, I decided to solder a grounding wire between the control board and the metal frame of the LCD.

This is the test setup: CarHUD with Debug build powered by a bench power supply.  The backlight is the car LED fog light I got off of eBay.

I was excited to find out that the LED was powerful enough to be a backlight for the projector and that the display was in color!  Unfortunately, the color only lasted for 30 seconds and then switched to black.  This also happened over multiple power cycles, so I determined that anything emitting a bunch of electrical noise was going to cause this.

The bootup!

The Running!

Am I a little disappointed? Totally.  I was putting a lot of thought into this projector and it isn't working the way I wanted.  Maybe it is an issue because it's an older LCD panel.

Am I giving up?  On the LCD front, yes, but the project is continuing.

How am I going to make this work?  In my search for HUDs in cars, I came across the blog of Bill Wong.  I like his idea of 7 segment LEDs as a means of displaying the data.  In my case, my projection isn't that great of a distance, so they should work.  I have the parts on order from Adafruit and they should get here soon.  The nice thing about these LED's is that they are controlled similarly to the 64 LED matrices I was going to use as a backlight, so I can do brightness changes.

More to come!