# BBC micro:bit – RGB Gradient

In this challenge we will use the BBC micro:bit to control a RGB LED to create a gradient light effect where the LED will fade from red to purple, to blue, to purple and back to red.

To do so we will need:

• A BBC micro:bit
• A RGB LED
• 3 resistors (100 Ohms)
• 4 wires

#### RGB Colour Codes

Did you know that every colour on the screen can be represented using an RGB code (Red, Green, Blue) code. This code consists of three numbers between 0 and 255, indicating how much red, green and blue are used to recreate the colour.

For instance the RGB code for:

• Red is (255,0,0)
• Green is (0,255,0)
• Blue is (0,0,255)
• Yellow is (255,255,0)
• Orange is (255,165,0)

Check the following RGB Color picker to see how RGB codes work:

#### Electric Circuit

An RGB LED is a 3-in-1 LED. It consists of a RED LED, a Green LED and a Blue LED all within the same component. It has 3 cathodes (+ pins) that can take different amperages. It has 1 common anode (- pin).

This is how we will connect our RGB LED to our micro:bit.

The purpose of the resistors is to limit the amperage in the circuit and hence protect the LED from receiving a too strong current (which could damage the LED). The resistors we use here are 100 ohms (Brown Black Brown rings).

#### micro:bit Code

Here is the code needed in the micro:bit to implement the gradient fading effect:

Step 1: Initial RGB values
Step 2: Red to Blue Gradient
Step 3: Blue to Red Gradient

Tweak this code to create other gradient animations:

Gradient 3: Green, Yellow, Magenta, Cyan, Green

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###### One comment on “BBC micro:bit – RGB Gradient”
1. marie-anne says:

That’s a really cool and simple project! Thank you!

However the example code does not correspond to diagram. for the “analog write” command you need to have:

GreenPin -> P0
BluePin -> P1
RedPin ->P2

In order to match the drawing.