My family has always been into Christmas lights and creating custom decorations, so when I read this blog post on how to hack GE Color Effects Christmas lights, I knew I needed to try it out myself. I decided to use an XBee Programmable so that I could control the lights wirelessly and try out the new built-in Freescale co-processor.
For this project I'm sending RGBA (Red Green Blue Alpha) values for each LED over a ZigBee network to the FreeScale co-processor built into the XBee Programmable. The code on the co-processor uses a PWM to send the RGB values on a data line to the LEDs in the strand. Each LED on the strand has an 8051 microprocessor in it that decodes the signal and sets the LED color and brightness. Voila, wireless control of 50 tri-color LEDs. The strands themselves support a refresh rate of up to ~24Hz when setting all 50 LEDs (faster if you are setting fewer LEDs). Using a compact over the air representation for the LED values (removing the brightness or ALPHA portion), I can get ~10Hz refresh rates in real time over the wireless network.