"Tap-tap, is this thing on?" I'm catching up on things that have already happened. Once I'm sure I'm posting in the right place I'll be adding updates over the next few weeks.

These will be reposts of my original notes on our website https://forum.makeit.zone/t/element-14-micro-bit-summer-of-code-club-challenge-2019.


We were very lucky to be selected as winners of Element14's Micro:Bit Summer Code Club Challenge!


To help us bring coding to our community we received:


- a micro:bit Club Pack

- 5 x Kitronik Inventor kits


The challenges I set myself for this code club were:


  • any age, including adults
  • scalable in both number of participants, and complexity
  • fun!


The final idea: An electronic puzzle/escape room device.


System Outline


Lock Box

There will be a central "lock box" to which the "lock-master" micro:bit will be connected.

The lock box will be any container that can be secured in such a way that a servo can be used to "unlock". The box will contain some sort of reward or prize for participants.


It will be programmed to listen on a known radio group.


There will be an admin mode that allows the mentor running the session to adjust the number of puzzle bits being used.


The lock-master awaits messages from the puzzle-bits that indicate they have been solved.


When all puzzle bits are solved, the servo is activated and the lock-box unlocked.


Things to Consider

Cheating. The initial code will probably just wait for 5 "unlocked" messages.


This can be enhanced:

  • check the serial number sent from each micro:bit
  • an initial "setup" stage that records the serials of the "allowed" puzzle-bits


Suggestion: leave it open, have a discussion about hacking, let participants try to hack, secure, and hack again


Puzzle Bits

These are the micro:bits that participants will work with.


They will be provided with a template that includes the steps needed to send the "puzzle solved" message to the lock-master.


Participants then create a puzzle (as simple or as complicated as they like) for a user to solve.


Session Outline

Minimum session time: 2 hours.

  • welcome
  • brief description of micro:bit
  • show maker:code
  • download basic "press button->message" example
    • verify download is working with known good code
  • go over basic loops and logic
    • practice
  • go over displaying messages
    • practice
  • introduce the sensors
    • practice. Potentially limit sensors covered if time is short.
    • Challenge: Come up with a puzzle for a person to solve on your micro:bit
  • introduce template code that sends "solved" message to master
  • Wrap up:
    • swap puzzle-bits with other participants, see if group can unlock the lock box and earn the reward!



  • movement based puzzles (accelerometer, compass)
  • physical inputs (switches, LDR, etc)
  • other sensors
  • connecting to more advanced computers (eg puzzle on Raspberry Pi, BrainPad Arcade, ...)



  • location of a cooler full of ice blocks, etc
  • discount coupons to an escape room (working on that for Courtenay.)


Next blog post will feature the CAD files for the lock box.