About this project

 

This project shows how to use the BBC micro:bit radio to make a large display using multiple micro:bits.

 

What you'll need

 

4 x BBC micro:bit (or more if you have them)

1 x Micro USB

1 x Computer or tablet

8 x AAA Batteries & 4 x Battery Holders

 

Project walk through

 

  • The 5 x 5 LED display on the BBC micro:bit is great, but it sure takes a long time to scroll though a long message. Is there a way we could use a number of micro:bits to make a bigger display? Yes there is! We'll use the micro:bit radio to have four micro:bits work together to combine their LEDs.

 

 

  • From the 'Radio' section use a 'radio set group' block to setup the radio. Choose a group number that no-one else in the room is using, in this example we've chosen group 1.

 

make:code radio set group block

 

  • The way we're going to spread our message across the micro:bits is to start each micro:bit at a different letter. Create a 'letter' variable and set it to zero (i.e. the first letter of the message). Show the value on startup so we know what it is set to.

 

creating letter variable

 

  • We'll use button B to move to the next letter. Let's update the display each time the value changes.

 

changing letter variable

 

  • We'll use button A to send the message. You can send any message you like!

 

Send a radio message

 

  • Now for the receiver. When we receive a message we want to show the string starting at the letter we set in the 'letter' variable. From the 'Text' section find the 'substring of' block. This takes a string (the 'receivedString' variable in our case) and cuts it starting at a letter we've chosen (the 'letter' variable in our case) and finishing after a chosen number of letters (set to 100 here so we get all the remaining letters). This is the computer equivalent of cutting words out of a magazine.

 

show received message from letter start

 

  • The program is finished! Download it to all four micro:bits.

 

  • Connect all the micro:bits up to batteries and lay them out like this.

 

micro;bit display pre-setup

 

  • Press the B buttons on the top row until they are set to show letters 0, 1, and 2. If you make a mistake just reset the micro:bit (the button is on the back).

 

micro:bit display setup

 

  • Press the A button on the the bottom micro:bit - you should see the message scroll across the other three!

 

micro:bit display in motion

 

Next steps

 

  • Can you send different messages from the transmitting micro:bit? You could re-use the letter number variable to choose a message.
  • Can you make all four micro:bits show the scrolling message? This will require you to make the message show when the A button is pressed (as this micro:bit wont receive the radio message).
  • Can you think of other displays you could make out of micro:bits? If you have 10 (i.e. in a micro:bit Club pack) you could position them to have 15 x 15 LEDs to show a picture!