Frank Zhao wrote in to show us about this deceptively simple looking modification he made to his car. He wanted to bring a bit of the future into his driving experience with a HUD (Heads Up Display). As you can see in the video above, the best example of these is the cockpit of a state-of-the-art fighter jet. There is additional data displayed directly in your field of view to allow you to keep your eyes on the target, or road.
This type of display is usually created by angling a piece of glass so that you can see through it, but also see the reflection of some lights or an instrument panel at the same time. Most cars have a windshield that is conveniently already tilted at an angle that works! Frank saw this and got to work.
His modification exists as an LED strip mounted to his dash in a custom 3D printed case. The case has walls to keep the LEDs themselves from being visible to Frank or other drivers. However, the top of the case is open, allowing Frank to see the reflection of the LED strip quite clearly on his windshield. He’s tapped into the OBDII port of his car to pull information, such as speed, and then written a bit of code to create a useful display from those LEDs.
It is programmed to have three different modes: voltmeter, tachometer, and speedometer. The mode switching is “context aware”: When the car is moving, the mode changes to speedometer. If I rev the engine without the car moving, the mode changes to tachometer. When the engine is off, the voltmeter shows me the car’s battery voltage. When transitioning between the modes, there’s a few preset transition animations that are randomized. When the car is off, the circuit goes into sleep mode.
Since this is mounted on his dash, he also has to take into account the amount of sunlight. Frank has added a photoresistor that can detect the amount of light and adjust the LED brightness on the fly. This is most important at night when the LEDs have the potential to actually obstruct his view and need to be dimmed considerably.
You can find more information about both using and building the system on Frank’s site. He’s giving away the plans and code as well!