Circuit 06 - RGB LED

Background

You know what’s even more fun than a blinking LED? A multi-coloured one. RGB, or red-green-blue, LEDs have three different colour-emitting diodes that can be combined to create all sorts of colours. In this circuit, you’ll learn how to use an RGB LED to create unique colour combinations. Depending on how bright each diode is, nearly any colour is possible!

Parts List

	Name	Quantity
	LED (RGB)	1
	330Ω Resistor (Orange-Orange-Brown)	3
	Jumper Wire (Any colour)	9
	Potentiometer (POT)	1

Circuit Diagram

Breadboard Diagram

Load the code in example ADKL3_06A and see what happens.

What You Should See

You should see your LED turn on, but this time in new, crazy colours! If it isn't, make sure you have assembled the circuit correctly and verified and uploaded the code to your board or see the troubleshooting tips below.

Troubleshooting

LED Remains Dark or Shows Incorrect Colour

With the four pins of the LED so close together, it’s sometimes easy to misplace one. Double check each pin is where it should be

Circuit 06B - Colour Mixer

A LED blinking different colours is awesome but just the LED blinking by itself is not awesome enough. Let’s take it one step further and use the potentiometer to control the colour of the LED. Load the code ADKL3_06B.

What You Should See

You should see your LED turn on, but this time in new, crazy colours! If it isn't, make sure you have assembled the circuit correctly and verified and uploaded the code to your board or see the troubleshooting tips below.

Troubleshooting

Seeing Red?

The red diode within the RGB LED may be a bit brighter than the other two. To make your colours more balanced, use a higher ohm resistor. Or adjust in code:

analogWrite(RED_PIN, redIntensity); to analogWrite(RED_PIN, redIntensity/3);

The Code Explained

The idea behind the code is to divide the input from the potentiometer into three zone. One zone with the colour blue absent, one with red absent, and one with green absent. The other two colours will be calculated from the input.

Code	Explanation
(long)767 / (long)1023;	Type casting is a way to force a variable into another type. In our code, the number 767 and 1023 is treated as integer normally. By putting (long) in front of the number, the program will now treat them as long integer

Can you create all the colours in the colour wheel?

Real World Application

Many electronics such as videogame consoles use RGB LEDs to have the versatility to show different colours in the same area. Often times the different colours represent different states of working condition.

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Circuit 05 - Multiple LEDs	Circuit 07 – Temperature Sensor