Arduino Project: Custom Interior Lighting for Car (#1)

Описание: I've had a decent ambient lighting setup in my car for a few months (   • 2011 Ford Escape Custom Ambient Lighting  ). And while it looks cool, I knew I could do better. So I set out to design the ultimate lighting setup. Using an Arduino to drive the LEDs would give me ultimate flexibility, since I would be the one writing the code. If I come up with a new idea for a cool animation, I just have to write the animation and upload the new code.

In this video I walk through some of the pieces I've been working on. I'll also add some more information here that I either left out or was too boring to include in the video.

Arduino Mega. Not much to say other than it has lots more pins than the Uno and lots more memory. Both useful characteristics for me.

Display. The display is an OLED character display from Newhaven Displays (NHD‐0216KZW‐AB5). Similar displays have a reputation for being quite buggy when being integrated with the Arduino. What I have found is that every person who reports this tries using the display in 4-bit mode. If you hook it up with 8 data pins instead of 4, the default LiquidCrystal library works flawlessly. Once I did this, all the weird behavior was totally gone.

Rotary Encoder (http://www.adafruit.com/products/377). The rotary encoder is a simple device that reads rotation. For each click of the rotary encoder, it reports which direction it was turned. This makes it very handy for navigating a menu. This particular encoder also has an integrated button that I use as a Select function. There are numerous cars and other devices that use this in a similar fashion.

The LED strips are generic 12V RGB strips (http://www.adafruit.com/products/285 or http://www.adafruit.com/products/346). The Arduino only outputs 5V, however, so it cannot power these directly. Instead, the Arduino drives a set of transistors that uses the 5V from the Arduino to switch 12V to the LEDs. At this point, I have each channel (red, green, and blue) hooked to their own individual pins and use analogWrite() on those. Later on, I will likely add shift registers to expand the number of PWM outputs so I can use more channels.

Each "LED" in the strip is actually composed of three smaller LEDs: red, green, blue. By varying the amount of each color, you can vary the overall color of the strip. For example, pure red and pure blue will yield a purple color. Adding green to this mix will make the purple whiter.

As I mention in the video, humans don't think in RGB. In this video, I briefly describe the HSL color space that is a more natural mapping to describe colors. For the animations, I expect to use a mixture of both color spaces, since some effects will be easier to implement in one instead of the other.

Parallel processing / Threading. The Arduino, like any single-core machine, is only capable of doing one thing at a time. I found a library called mthread that lets you fake it. As I mentioned, this will become extremely important because I want to be able to control each strip seemingly independently of the rest.

If you have any other questions, please ask!