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About the Code-a-Key Backpack

What is Code-a-key

The Code-a-Key Backpack is an adapter board to connect the micro:bit to the Makey Makey and give the micro:bit access to the Makey Makey key and mouse pins on the back of the Makey Makey.

On the front of the Code-a-Key Backpack you will find first and foremost an edge connector for the micro:bit in the center of the board. The micro:bit is inserted into this connector with the LED array facing out as shown in the image below.

This connector provides power to the micro:bit from the Makey Makey and facilitates communication between the micro:bit and the different pins on the back of the Makey Makey as well as the row of pins just below the connector (more on those later!)

The backpack has four different LEDs on it. Two LEDs are power indicators; one for the Makey Makey 5 volt (5V) power supply and one for the 3.3 volt (3.3V) power supply for the micro:bit. Both of these LEDs should be on whenever your Makey Makey is powered via USB.

The other two LEDs which are green in color are indicator LEDs for Key and Mouse activity on the Makey Makey. Anytime a Key or Mouse input is used on the Makey Makey these LEDs will light up. As you use your Makey Makey these lights will light up and turn off. These lights will also do the same when your micro:bit is controlling the Makey Makey.

On the back of the backpack you will see a number of different electronic parts and pieces which take care of all of the magic to enable the micro:bit and Makey Makey to talk to one another. The main thing to focus on is the pin headers that plug into the back of the Makey Makey in three areas… Keyboard on the left, mouse control on the right and power at the top. When handling the backpack these pins can get bent if care isn’t taken when plugging-in and removing the backpack from the Makey Makey. If you do bend a pin, you should be able to carefully straighten it with a pair of needle nose pliers.

Back to the front... Just below the edge connector is a row of female pins where advanced users can attach external inputs and outputs to the backpack. Some example components could be LEDs, Servo Motors, simple analog sensors (light, temperature, etc). These pins correspond to the pin numbers on the micro:bit (0-20). We also provide a 3.3V supply pin as well as two Ground pins as well. If you are interested in using some of the more advanced options for the micro:bit and a breadboard, this header will be a gold mine for you!

Putting Everything Together

Now that you are familiar with the Code-a-Key Backpack, the Makey Makey and the micro:bit, let's jump in and put it all together!

We will start assembly by plugging the backpack into the back of your Makey Makey. Taking each board in-hand carefully align all of the pins on the backpack with the black pin headers on the Makey Makey and firmly press them together. Take a moment to double check that all of the pins made it into the headers and nothing is misaligned.

The next step is to insert your BBC micro:bit into the edge connector on the Code-a-Key Backpack. Holding the micro:bit with the LED array facing out (away from the backpack) insert the micro:bit bottom edge into the edge connector with a satisfying click. This connection should be firm and your micro:bit shouldn’t fall out if you turn everything upside down or move it around.

We will need both USB cables while working with the Code-a-Key Backpack. You will need the Makey Makey USB cable for the Makey Makey to work and use of your finished project. You will also need the micro:bit USB cable to upload code to the micro:bit.

Start by plugging the Makey Makey into your computer. This will power both your Makey Makey and the micro:bit. Both 5V and 3.3V LEDs will turn on and the micro:bit will start running whatever code was last uploaded to it. If your micro:bit is new, it will start going through a demo cycle showing LEDs and making noises!

Now, using the micro:bit USB cable plug the micro:bit into your computer! On your computer the micro:bit should show up as an external drive similar to a USB thumb drive. You are good to go!

NOTE: We know that your computer may have a limited number of USB ports and we are sorry for that inconvenience. If you do not have a USB port dongle, then you will need to swap which cable is plugged into your computer. If you are programming the micro:bit plug the micro:bit into USB and if you are testing your code / using your project plug the Makey Makey into your computer.


A First Code-a-Key Project

Now that you are familiar with all of the parts and have assembled your Code-a-Key controller it is now time to start using it! This first time use is usually called a "Hello World" project. We have a perfect one for you to get familiar with how to do the following...

  • Start a new project in Microsoft MakeCode for micro:bit
  • Install the Code-a-Key Extension for micro:bit
  • Program your first project using the Code-a-Key Backpack
  • Modify your first project for a different use!


Click here go to Project



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About the Code-a-Key Backpack