micro:bit Breakout Board Hookup Guide

Contributors: Shawn Hymel
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The micro:bit, by itself, offers a vast array of possibilities and potential projects, considering it includes an onboard temperature sensor, accelerometer, compass, LED array, Bluetooth radio, and more. However, when you’re ready to branch out beyond those initial capabilities, like connecting to an SD card for logging, you’ll need to break out some of the pins on the micro:bit’s card edge connector. For that, we’ve got you covered with the micro:bit Breakout Board.

SparkFun micro:bit Breakout (with Headers)

SparkFun micro:bit Breakout (with Headers)


There’s also a version without headers, if you care to solder your own or use wires instead.

Required Materials

To follow along with this project tutorial, you will need the following materials:

Suggested Reading

If you have not yet used the micro:bit, check out this guide first.

Getting Started with the micro:bit

March 21, 2017

The BBC micro:bit is a compact, powerful programming tool that requires no software installation. Read on to learn how to use it YOUR way!

If you aren’t familiar with the following concepts, we recommend checking out these tutorials before continuing.

How to Solder: Through-Hole Soldering

This tutorial covers everything you need to know about through-hole soldering.

How to Use a Breadboard

Welcome to the wonderful world of breadboards. Here we will learn what a breadboard is and how to use one to build your very first circuit.


A tutorial on all things resistors. What is a resistor, how do they behave in parallel/series, decoding the resistor color codes, and resistor applications.

Light-Emitting Diodes (LEDs)

Learn the basics about LEDs as well as some more advanced topics to help you calculate requirements for projects containing many LEDs.

Hardware Overview

The micro:bit Breakout board allows you to utilize all of the pins on the micro:bit and opens up some previously inaccessible communication ports, like I2C and SPI.

micro:Bit breakout

Top-down diagram of the micro:bit breakout board


Most of the micro:bit’s pins can be configured for one or more functions.

Pin Function 1 Function 2 Description
GND Ground
GND Ground
3V3 3.3V
0 Analog In Connected to large pin 0
1 Analog In Connected to large pin 1
2 Analog In Connected to large pin 2
3 Analog In LED Column 1 Controls part of LED array
4 Analog In LED Column 2 Controls part of LED array
5 Button A Connected to Button A on micro:bit
6 LED Column 9 Controls part of LED array
7 LED Column 8 Controls part of LED array
8 Open GPIO pin
9 LED Column 7 Controls part of LED array
10 Analog In LED Column 3 Controls part of LED array
11 Button B Connected to Button B on micro:bit
12 Open GPIO pin
13 SCK GPIO or SPI clock
16 Open GPIO pin
19 SCL GPIO or I2 clock
20 SDA GPIO or I2 data

Power Pin

The pin listed as 3V3 can be used as an input (regulated 3.3V, do not exceed 3.6V!) or an output if you plug a battery pack or USB into the micro:bit.

LCn Pins

The pins labeled with LCn (e.g. LC1, LC8) refer to pins that are used to control the LED array on the front of the micro:bit. You can use them as GPIO, but you’ll often get weird patterns to show up on the LEDs, or when you write to the LED array, you may see unexpected behavior. If you use them as GPIO, we recommend disabling the LED display.

Hardware Assembly

Attach Headers

If you have the version of the breakout board without headers, solder some breakaway headers to the board. You can also solder wire directly to the breakout.

Solder headers to the micro:bit Breakout board

Build Example Circuit

Note: The micro:bit must be facing up in order to make electrical connections to the pins.

To begin, let’s light up an RGB LED. Attach the micro:bit to the breakout board, place the breakout board onto a breadboard, and connect an RGB LED through 330 Ω resistors. Use the image below to aid you in wire up the circuit.

Remember, LEDs are polarized parts and can only work properly in one orientation. The longest leg of the LED goes where the black GND wire is in the circuit.

micro:bit breakout board hookup Fritzing

Having a hard time seeing the circuit? Click on the wiring diagram for a closer look.

Example: Cycling Colors on an RGB LED

You can download the code from the emulator, or check out the project’s page here:

Copy the .hex file to your micro:bit drive, and you should see a fancy array of colors appear on your LED!

micro:bit cycling colors

Resources and Going Further

With the micro:bit breakout board, you can start introducing more sensors, lights, and motors into your project! For more information, check out these resources:

Need some inspiration for your next project? Check out some of these related tutorials:

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Here are a few tips in using the PicoBoard with Scratch v1.4. The PicoBoard allows us to write Scratch programs that interact with a variety of sensors on the PicoBoard. These sensors include: sound, light, a slider, a push button, and 4 external sensors (A, B, C, and D).

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