How to Use LED RGB: Examples, Pinouts, and Specs

An RGB LED is a Light-Emitting Diode that combines Red, Green, and Blue light sources in a single package. By adjusting the intensity of each color, it can produce a wide spectrum of colors, making it a versatile component for color mixing and decorative lighting. Common applications include mood lighting, display panels, and DIY electronics projects with microcontrollers like the Arduino UNO.

• Forward Voltage (Typical): Red: 2.0-2.2V, Green: 3.0-3.2V, Blue: 3.0-3.2V
• Forward Current: 20mA (per channel)
• Luminous Intensity: Varies by color and manufacturer
• Viewing Angle: Typically 120 degrees

Note: The common pin may be either anode or cathode, depending on the type of RGB LED (common anode or common cathode).

1. Identify the Type: Determine if your RGB LED is common anode or common cathode.
2. Connect the Pins: Connect the common pin to either VCC (for common anode) or GND (for common cathode).
3. Resistors: Connect a current-limiting resistor (typically 220-330 ohms) in series with each of the color anode/cathode pins.
4. Control: Use a microcontroller to adjust the voltage (PWM - Pulse Width Modulation) on each color pin to mix colors.

• Current Limiting: Always use current-limiting resistors to prevent damage to the LED.
• PWM Control: Use PWM to control the brightness of each color for color mixing.
• Heat Dissipation: Ensure proper heat dissipation if driving the LED at high brightness levels.

// Define the RGB LED pins
const int RED_PIN = 11;
const int GREEN_PIN = 10;
const int BLUE_PIN = 9;

void setup() {
  // Set the LED pins as output
  pinMode(RED_PIN, OUTPUT);
  pinMode(GREEN_PIN, OUTPUT);
  pinMode(BLUE_PIN, OUTPUT);
}

void loop() {
  // Set the color to purple (Red + Blue)
  analogWrite(RED_PIN, 255);   // Red at full intensity
  analogWrite(GREEN_PIN, 0);   // Green off
  analogWrite(BLUE_PIN, 255);  // Blue at full intensity

  delay(1000); // Wait for 1 second

  // Set the color to aqua (Green + Blue)
  analogWrite(RED_PIN, 0);     // Red off
  analogWrite(GREEN_PIN, 255); // Green at full intensity
  analogWrite(BLUE_PIN, 255);  // Blue at full intensity

  delay(1000); // Wait for 1 second
}

Note: The above example assumes a common anode RGB LED. For a common cathode, invert the PWM values (use 255 - value).

• LED Not Lighting Up: Check the polarity of the LED and ensure the common pin is correctly connected.
• Incorrect Colors: Verify that the pins are connected to the correct color channels.
• Dim or Flickering Light: Ensure that the current-limiting resistors are of the correct value and that the power supply is stable.

• Polarity Check: Use a multimeter to confirm the common pin and individual color pins.
• Resistor Values: Recalculate the resistor values if you are using a different supply voltage.
• PWM Frequency: If the LED is flickering, adjust the PWM frequency in your microcontroller code.

Q: Can I connect an RGB LED directly to an Arduino without resistors? A: No, you should always use current-limiting resistors to prevent damage to both the LED and the Arduino.

Q: How do I make white light with an RGB LED? A: To create white light, you need to mix red, green, and blue at full brightness. However, the resulting white may not be perfectly balanced due to differences in LED color intensity.

Q: Can I use a single PWM pin to control all three colors? A: No, you need individual PWM control for each color to mix colors effectively.