18. Case 17: Alarm Device

18.1. Introduction

Build an alarm device with the micro:bit.


18.2. Quick to Start


Nezha expansion board × 1

micro:bit × 1

LED-red × 1

RJ11 wires × 1

Bricks × n


Bricks details


Connection Diagram

  • Connect the red LED to the J1 port on Nezha expansion board.


Bricks Build-up

  • Build a device as the pictures indicate:




Video link:https://youtu.be/bYN6-6PskHQ

18.3. MakeCode Programming

Step 1

Click “Advanced” in the MakeCode drawer to see more choices.


We need to add a package for programming. Click “Extensions” in the bottom of the drawer and search with “PlanetX” in the dialogue box to download it.


Note: If you met a tip indicating that the codebase will be deleted due to incompatibility, you may continue as the tips say or build a new project in the menu.

Step 2

Programme as the picture shows:



  • Press button A to alarm and the red LED flashes; press it again to stop the alarming and the LED turns off.