Responsive Lighting: Bluetooth NeoPixels

Why buy an $80 commercial smart light strip when you can build a customizable one for $15? The Bluetooth WS2812B Controller project fuses parsing Serial commands with the FastLED library to create gorgeous, responsive room lighting.

The FastLED Library Magic

WS2812B strips (NeoPixels) only have 3 wires: 5V, GND, and a single Data line.

• They are "Addressable." You can tell LED #5 to be Red while LED #60 is Blue.
• The FastLED.h library handles the excruciatingly complex timing required for the Data line.
• leds[0] = CRGB::Red; FastLED.show();

Parsing RGB Strings from Bluetooth

The true challenge is getting the exact color from your phone.

1. You use an Android App (like Bluetooth Electronics) to dial in a custom purple color on a color wheel.
2. The app sends a string to the HC-05 Receiver: R:150,G:0,B:200\n.
3. The Arduino reads the string. It uses C++ String.indexOf() to find the commas, and String.substring().toInt() to pull out the exact 150 and 200 integers.
4. It dynamically feeds those parsed numbers directly into fill_solid(leds, NUM_LEDS, CRGB(r, g, b));.

The Power Warning

• Arduino Uno/Nano: The command logic.
• HC-05 Bluetooth Module.
• An Arduino pin can supply 500mA maximum. A 1-meter strip of 60 NeoPixels running full white draws 3.6 Amps! You must power the LED strip via an external 5V/5A power supply. If you plug the strip directly into the Arduino's 5V pin, you will instantly burn out the voltage regulator.