Reaction Time Tester

Test yourself with this Python-based mini-game for the micro:bit and OLED! Written by Jensen from Raffles Institution.


  • Assemble a reaction time tester.
  • Try not to break it when testing yourself!


  • 1 x Brain
  • 1 x You

Step 1 – Input/Output

  • Attach the MicroBit to the Breakout Board.
  • Connect the LED to pin 12, which is a digital pin.
  • Connect the light detector to pin 8, another digital pin.
  • Brown to G (ground), red to V (voltage) and orange to S (signal).
  • These tell us if light is on or off.
  • Connect the OLED display to the I^2C pins. Any one set will do.
  • Connect your micro:bit to the computer, and download the Mu Editor.

Step 2 – File Transfer

  • We need to download some modules to be used in the project.
  • From This link, download the module as a zip file.
  • Write the code (first screenshot)  in Mu Editor to import the files.
  • Be sure to have the files in the same folder as the project.
  • Transfer a few of the files from your computer to the microbit.
  • On Windows, be sure to put the files in a folder under users/”Username”/mu-code for them to be detected my mu-editor
  • These files are the modules that are not originally present on the micro:bit for you to import.

 Step 3 – Loading Screens

  • This step isn’t really necessary , but it adds a little flair into your project.
  • We display this loading on the OLED module
  • Using the module “add_text”, we can display text and other characters onto the display
  • We show the animation using the function “loading_screen()”
  • If you want more variations of the loading screen, head down to the bottom of the post.

Step 4 – Code the Game

  • Here’s the actual test itself.
  • First, we have to have a time to wait before showing the indicator for the player to press the button
  • We randomly generate the number and parse it into milliseconds by adding “000” to the end of the number after turning the original number into a string.
  • The variables time1 and time2 refer to 2 arbitrary points in time before the “#” ( the indicator to the player) symbol is shown.
  • One quirk about micropython and the MicroBit to note is that the time module is replaced by the utime module, and utime has to be imported instead of time.

Step 5 – A Little More Logic

  • This is the step where we calculate and display the player’s reaction time.
  • This is done by calculating the time between when the indicator is displayed and when the player presses the button.
  • Then, we display the player’s reaction time to the OLED display.


Bonus loading effects:

  • This one utilizes the light sensor and the LED to start the game.
  • It detects light and once the light is covered, the game will start.

This next animation is simple: display the characters “3”, “2” , and “1”, as a countdown before starting the game. The code is pretty self explanatory.