Two Colour LED Module with Arduino

Gradually alternate between colours with the two colour led module and the Arduino!

Written By: Cherie Tan

Difficulty

Easy

Steps

Gradually alternate between two colours with this LED module! In this guide, learn to create a fading effect with this two colour LED module and the Arduino. After completing this guide, you will understand how to fade an LED using a simple program with the Arduino IDE.

Step 1 The Two Colour LED module

Let's take a closer look at the Two Colour LED module! This is a KY-011 LED module which provides a red and green LED connected with a common cathode. Since the operating voltage is 2.0V-2.5V, you'll need a current limiting resistor to avoid burnout when connected up to the Arduino. There are three pins starting with the one on the furthest left. Signal: This pin is a signal pin, and can be used to emit a green light. Middle Pin : This pin is another signal pin, and can be used to emit a red light. GND: Though it is labelled '-' on the module, this is the ground pin also known as 'GND'. What is 'GND'? In electronics, we define a point in a circuit to be a kind of zero volts or 0V reference point, on which to base all other voltage measurements. This point is called ground or GND.

Step 2 Connect Two Colour LED Module to Breadboard

Insert the LED module into the breadboard as shown.

Step 3 Connect resistors to breadboard

Next, insert the resistors so that one end of each are connected to the S pin and middle pin respectively.

Step 4 Connect S Pin to Digital Pin 10

Connect a jumper wire from the S pin to Digital Pin 10. Make sure you're using a resistor as shown.

Step 5 Connect Middle Pin to Digital Pin 9

Next, connect a jumper wire from the middle pin to Digital Pin 9. Notice how both Digital Pins used have a ~ symbol next to them? On Arduino Uno, the PWM pins are labelled with a ~ sign. You can see these are Pins 3, 5, 6, 9, 10 and 11.

Step 6 Connect - Pin to GND

Finally, connect a jumper wire from the - Pin to GND on the Arduino. Any of the GND pins found on the Arduino will work.

Step 7 Sketch to Alternate Between Green and Red

int redpin = 9; // pin for red signal
int greenpin = 10; // pin for green signal
int val;

void setup() {
  pinMode(redpin, OUTPUT);
  pinMode(greenpin, OUTPUT);
}

void loop() {
  for(val = 255; val > 0; val--) { 
    analogWrite(redpin, val); //dim red
    analogWrite(greenpin, 255 - val); // brighten green
    delay(15);
  }
  for(val = 0; val < 255; val++) { 
    analogWrite(redpin, val); //brighten red
    analogWrite(greenpin, 255 - val); //dim green
    delay(15);
  }
}

You can adjust the amount of each colour using pulse-width modulation (PWM). Within the Arduino IDE is a built-in function called analogWrite(). This function can be used to generate a PWM signal. Using this function, we can give a value of 0-255. analogWrite(0) means a signal of 0% duty cycle. analogWrite(127) means a signal of 50% duty cycle. analogWrite(255) means a signal of 100% duty cycle. Now go ahead and copy and paste this code into the Arduino IDE. Make sure the right board and port is selected; These should mention (Arduino Uno). Watch how the LED gradually alternates between green and red!