# Use a Two Colour LED Module with micro:bit

## Make a Two Colour LED blink using the micro:bit

Written By: Cherie Tan

Difficulty
Easy
Steps
10

### Introduction

Want to make an LED light up and easily change their colours?

In this guide, we will learn to use a handy little LED module and make it blink using the micro:bit!

After completing this guide, you will understand how to use an LED and create a simple program using MakeCode.

If you're using the Micro:bit Advent Calendar, you'll need the contents of the bags labelled 1 and 25.

### Step 1   The Module

• Before we begin, let's take a closer look at the Two Colour LED module! There are three pins:

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.

• Voltage is the difference in electric potential between two points. As it is difficult to talk about voltage without a reference point, we need another point to compare it to.
• You might have noticed an 'R1' on the module, this stands for 'resistor'. However, the resistor here is actually a 0Ω resistor,  so we will need to use external resistors in the circuit!

### Step 3   Insert the Micro:bit into the Breakout board

• Make sure that the micro:bit is inserted in the right orientation, with the buttons facing inward as shown.
• Insert the micro:bit into the breakout board.

### Step 9   Make the LED flash red

```basic.forever(function () {
pins.digitalWritePin(DigitalPin.P0, 1)
basic.pause(250)
pins.digitalWritePin(DigitalPin.P0, 0)
basic.pause(250)
})
```
• The first program we will create will make the LED module flash red. So open up the Makecode Editor.
• Click on the Projects button
• Create a new document
• Copy and paste the Javascript code into the Javascript programming interface.
• Click on the 'blocks' interface button and you should now see the MakeCode blocks.

### Step 10   Upload the code to micro:bit

• First off, click the download button in the bottom left corner of the screen. This will download a hex file (computer program file)  which the micro:bit can read.
• Next, plug in your micro:bit, this will reveal a USB on your computer.
• Lastly copy across the downloaded file to the micro:bit by dragging and dropping it into the MICRO:BIT drive
• The micro:bit will flash as the code is being uploaded. Once done, unplug the micro:bit.
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