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2.4 Colorful Light

In this lesson, we’ll explore how to create various colors using an RGB LED and the Raspberry Pi Pico 2 W. By adjusting the intensity of the red, green, and blue components, we can mix light to produce a wide range of colors. This concept is based on the additive method of color mixing.

What is Additive Color Mixing?

Additive color mixing involves combining different colors of light to produce new colors. When red, green, and blue light are combined in various intensities, they can create any color in the visible spectrum. For example:

• Red + Green = Yellow

• Red + Blue = Magenta

• Green + Blue = Cyan

• Red + Green + Blue = White

• RGB LED

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	PURCHASE LINK
Pico 2 W Starter Kit	450+	Pico 2 W Kit

You can also buy them separately from the links below.

SN	COMPONENT INTRODUCTION	QUANTITY	PURCHASE LINK
1	Getting to Know Pico 2 W	1
2	Micro USB Cable	1
3	Breadboard	1	BUY
4	Jumper Wires	Several	BUY
5	Resistor	3(1-330Ω, 2-220Ω)	BUY
6	RGB LED	1	BUY

Schematic

The PWM pins GP13, GP14 and GP15 control the Red, Green and Blue pins of the RGB LED respectively, and connect the common cathode pin to GND. This allows the RGB LED to display a specific color by superimposing light on these pins with different PWM values.

Wiring

The RGB LED has 4 pins: the long pin is the common cathode pin, which is usually connected to GND; the left pin next to the longest pin is Red; and the two pins on the right are Green and Blue.

We use a higher resistance for the red LED because it is typically brighter than the green and blue LEDs at the same current.

Writing the Code

Here, we can choose our favorite color in drawing software (such as paint) and display it with RGB LED.

Note

• You can open the file 2.4_colorful_light.ino under the path of pico-2w-kit-main/arduino/2.4_colorful_light.

• Or copy this code into Arduino IDE.

• Don’t forget to select the board(Raspberry Pi Pico) and the correct port before clicking the Upload button.

// Define the GPIO pins connected to the RGB LED
const int redPin = 13;   // Red pin
const int greenPin = 14; // Green pin
const int bluePin = 15;  // Blue pin

void setup() {
  // Initialize each RGB LED pin as an output
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);
}

// Function to set the color
void setColor(unsigned char red, unsigned char green, unsigned char blue) {
  analogWrite(redPin, red);
  analogWrite(greenPin, green);
  analogWrite(bluePin, blue);
}

void loop() {
  // Red color
  setColor(255, 0, 0);
  delay(1000);

  // Green color
  setColor(0, 255, 0);
  delay(1000);

  // Blue color
  setColor(0, 0, 255);
  delay(1000);

  // Yellow color (Red + Green)
  setColor(255, 255, 0);
  delay(1000);

  // Cyan color (Green + Blue)
  setColor(0, 255, 255);
  delay(1000);

  // Magenta color (Red + Blue)
  setColor(255, 0, 255);
  delay(1000);

  // White color (Red + Green + Blue)
  setColor(255, 255, 255);
  delay(1000);

  // Turn off
  setColor(0, 0, 0);
  delay(1000);
}

After uploading the code, the RGB LED should cycle through red, green, blue, yellow, cyan, magenta, white, and then turn off, with each color displayed for one second.

Understanding the Code

1. Defining the Pins:

   Assign the GPIO pins connected to the RGB LED components.

   const int redPin = 13;
   const int greenPin = 14;
   const int bluePin = 15;
   

2. Initializing the Pins:

   Set the RGB LED pins as outputs.

   void setup() {
     pinMode(redPin, OUTPUT);
     pinMode(greenPin, OUTPUT);
     pinMode(bluePin, OUTPUT);
   }
   

3. Setting the Color:

   The setColor function uses PWM (Pulse Width Modulation) to adjust the brightness of each color component.

   void setColor(unsigned char red, unsigned char green, unsigned char blue) {
     analogWrite(redPin, red);
     analogWrite(greenPin, green);
     analogWrite(bluePin, blue);
   }
   

4. Looping Through Colors:

   In the loop() function, we call setColor() with different values to display various colors, each followed by a 1-second delay.

   void loop() {
     // Red color
     setColor(255, 0, 0);
     delay(1000);
     ...
   
     // Turn off
     setColor(0, 0, 0);
     delay(1000);
   }
   

Experimenting with Colors

You can create your own colors by adjusting the values passed to setColor(). The values range from 0 (off) to 255 (full brightness). For example:

• Orange: setColor(255, 165, 0);

• Purple: setColor(128, 0, 128);

To find RGB values for specific colors, you can use a color picker tool or software like Paint.

Conclusion

In this lesson, you’ve learned how to control an RGB LED using the Raspberry Pi Pico and how to create various colors by mixing red, green, and blue light. This knowledge is fundamental for projects involving LED displays, mood lights, or any application requiring color control.