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!
