How to control a RGB LED Strip Light with a Raspberry Pi Zero W

In this guide, you'll learn how to wire a 12 V RGB LED strip light to your Raspberry Pi Zero W and then control each color channel both from the command line and with Python.

What you'll need

• Raspberry Pi Zero W (any other Pi model will work, too)
• 12 V RGB LED strip light (e.g. SMD5050)
• 3x TIP120 Darlington transistors
• 12 V power supply capable of supplying enough current for your strip (check its specs for amperage per meter)
• Jumper wires for all connections

What you are going to build

Wiring schematic showing the connections between power supply, Raspberry Pi, TIP120 transistors, and RGB LED strip light

1. Identify the LED strip light's wires

At one end of the LED strip light you'll see four leads or pads, typically labeled:

12V  G   R   B

• 12V (or +) goes directly to the positive terminal of your 12V supply.
• G, R, and B each feed one color channel.

2. Wire the TIP120 transistors

For each color channel:

• Collector (middle pin) → strip's G, R, or B wire
• Emitter (one outer pin) → common ground (tie back to your 12 V supply's negative)
• Base (the other outer pin) → Raspberry Pi GPIO pin

Tip: insert a ~1 kΩ resistor between each GPIO pin and its transistor base. The base resistor protects both your Pi and the transistor, while still allowing enough current to switch the LED strip light fully on.

3. Tie all grounds together

Connect the Raspberry Pi's GND pin and the 12 V supply's negative terminal to the same ground rail. That way, the TIP120 emitters and the Raspberry Pi share a common reference.

4. Assign GPIO pins

Raspberry Pi Zero GPIO Pinout

On the Pi Zero's 40-pin header, pick three GPIOs for your colors. I'm using the following GPIO pin mapping:

• GPIO 27 → red
• GPIO 17 → green
• GPIO 22 → blue

And use any GND pin to complete the common ground.

5. Power up and test

1. Power your 12 V supply (which now feeds +12 V to the strip and ground to the TIP120s).
2. Boot the Raspberry Pi normally.
3. First you will need to start the pigpiod daemon which is required for GPIO control:

   sudo pigpiod

4. Now that everything is wired up, you can control the LED strip using the pigs command (from the pigpio library), which allows PWM control of GPIO pins.
5. PWM value range:
   • 255 = full brightness
   • 0 = off
   • Values in between dim the color
6. Example: Set strip to orange (RGB 255, 165, 0):

   pigs p 27 255   # Red to full
   pigs p 17 165   # Green to medium
   pigs p 22 0     # Blue off

   This will mix red and green to produce orange.

6. Python code

The python code for controlling the LED strip light is available in the GitHub repository https://github.com/janrothen/ledstriplight.