13. Case 09: Invading Detection Device#

13.1. Introduction#

This is an intrusion detection device. When the ultrasonic sensor detects that someone is approaching, it will automatically turn on a red light and alarm through the buzzer on the micro:bit. If the ultrasonic sensor does not detect anyone, it will automatically turn on green light.


13.2. Quick Start#

Materials Required#

Nezha expansion board × 1

micro:bit × 1

LED-green × 1

LED-red × 1

Sonar:bit × 1

RJ11 wires × 3

Tips: You may need to purchase Nezha Inventor’s Kit if you want all the above compoents.

Connection Diagram#

Connect the sonar:bit to J1, red LED to J2 and green LED to J3 on the Nezha expansion board as the picture shows.


Assembly Video#

Video Reference: https://youtu.be/jw9_wlNIiHw

Assembly Steps#










13.3. MakeCode Programming#

Step 1#

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


For programming, we need to add a package: click “Extensions” at the bottom of the MakeCode drawer and search with “PlanetX” in the dialogue box to download it.


Notice: If you met a tip indicating that some codebases would be deleted due to incompatibility, you may continue as the tips say or create a new project in the menu.

Step 2#

Code as below:#




You may also download it directly below:


While the sonar:bit detects the object, the red LED lights up and the buzzer alarms.