Two Colour LED Module with Arduino
Gradually alternate between colours with the two colour led module and the Arduino!
Written By: Cherie Tan
![Dash icon](https://fast.littlebird.com.au/static/guides/dash.webp)
Difficulty
Easy
![Steps icon](https://fast.littlebird.com.au/static/guides/steps.webp)
Steps
7
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.
![](https://files.littlebird.com.au/guides/2382_img1.png)
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.
![](https://files.littlebird.com.au/guides/2383_img1.jpeg)
Insert the LED module into the breadboard as shown.
![](https://files.littlebird.com.au/guides/2384_img1.jpeg)
Next, insert the resistors so that one end of each are connected to the S pin and middle pin respectively.
![](https://files.littlebird.com.au/guides/2385_img1.jpeg)
Connect a jumper wire from the S pin to Digital Pin 10. Make sure you're using a resistor as shown.
![](https://files.littlebird.com.au/guides/2386_img1.jpeg)
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.
![](https://files.littlebird.com.au/guides/2387_img1.jpeg)
Finally, connect a jumper wire from the - Pin to GND on the Arduino. Any of the GND pins found on the Arduino will work.
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!