Someone kindly sent me some LPD8806 strip to create a version of my Digital Light Wand with LCD + SD reader light painting tool.
You can select a bitmap image on the SD card using the LCD display, and then send it to the strip.
I’ve now added the Gamma Lookup Table that I came across in one of the LPD8806 examples, which seems to do a better job of converting 8bit RGB values to 7bit RGB due to the way our eyes work!
Previously I was just bit shifting, but the Gamma lookup helps produce an image that looks more comparable to the input image.
These LED strips are fun and glowy. There are 32 RGB LEDs per meter, and you can control each LED individually! Yes, that’s right, this is the digitally-addressable type of LED strip. You can set the color of each LED’s red, green and blue component with 7-bit PWM precision (so 21-bit color per pixel). The LEDs are controlled by shift-registers that are chained up down the strip so you can shorten or lengthen the strip. Only 2 digital output pins are required to send data down. The PWM is built into each chip so once you set the color you can stop talking to the strip and it will continue to PWM all the LEDs for you.