Lights belong to every Christmas tree. In my interation of the Christmas tree, I want to be able to control the lights myself. I want to turn each light on and off separately and have it change color. Moreover, I also want to program them with C++ and Arduino.

Physically, there are several types of light garlands. At first I thought of a normal light pendulum. So separate lights on a string. I did some research on individually addressable led lights. My best option: 12mm Diffused Thin Digital RGB LED Pixels (Strand of 25) - WS2801 (https://www.adafruit.com/product/322) via the distributor Adafruit. This was recommended to me by an employee of the store Gotron. The only disadvantage was the price: $39.95 (without shipping) for 25 lights. Especially if you know that I want at least 200 lights (the more lights, the sharper the text and graphics). I found cheaper options of the same type (WS 2811) on Amazon, but the delivery time for these was December 28 at the earliest...

I searched some more on Adafruit's website, here the delivery times were okay, it was a well-known distributor and in addition they had clear documentations about their LEDs. I ended up with their Neopixels led strips. So a led strip instead of individual led's. This could perhaps work even better, so the lights stay in place when text is displayed. They also had an updated version called the DotStars. These have some advantages over their predecessor that were interesting for their project: extremely fast data1 and PWM2 rates, suitable for persistence-of-vision displays, easier to interface to a broader range of devices, no strict signal timing requirements, don't have to worry about special pins, DMA requirements, interrupt management (e.g. Arduino Servo library or tone() function on the popular ATmega series).

After long consideration (because it is an investment after all) I chose to order 2x 5meter DotStar led strips of 30 leds each per meter. So in total I have 300 leds, spread over 10 meters, and no more money to eat a Buda Spaghetti.

With this, I couldn't do anything yet because my Arduino can't supply enough current to the LEDs. These leds require 1.8 amps for 1 meter (30 leds). So about 18 amps in total (depending on use). Also very important: the leds work on 5V. I bought a 5V & 10A power adapter , a capacitor to protect the strip and supply (Power Supply Smoothing) and a female DC Power adapter.

In a next blog post you will find a first test of the led lights