BBC micro:bit – Stopwatch

stopwatch-micro-bitIn this challenge we are going to create a Stopwatch (Countdown timer) using the BBC micro:bit.

You do no need a micro:bit to complete this challenge as you can use the online block editor and emulator ( to code and test your program.

Our program will use both input buttons A and B and the LEDs for as an output:

  • Button A will be used to initialised the stopwatch. Per default the stopwatch will be set at 3 seconds. By pressing button A, the user should be able to increment this value by 1 second at a time.
  • Button B will be used to start the count down. Once this button is pressed the stopwatch should automatically decrement by 1 every second and it should stop when it reaches the value 0 (zero).
  • The LEDs should be used to display the countdown value.


Step by Step Solution

Watch this step by step video tutorial to complete the code of your stopwatch.

Extension Task

Option 1:
Can you update this code further so that when both buttons A and B are pressed at the same time, the timer is paused.

Option 2:
Can you update this code so that when the timer reaches zero (0), it displays the text “Happy New Year!”.

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