5. Case 04: Farmlands Protection Device

5.1. Introduction

  • In order to protect the farmlands from people to get in, we can set a farmland protection device.

5.2. Function

  • Detect if there is any people approaching with the PIR sensor and Sonar:bit, if yes, program to remind people of not coming by lighting on the rainbow LED.

5.4. Picture


5.5. Hardware Connection

Connect the Sonar:bit to P1, the PIR sensor to P2 and the rainbow LED to P9 on IoT:bit.


5.6. Software Programming

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 “iot-environment-kit” 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.

5.7. Program

Drag the on start block from the drawer, initialize the strip connecting to P9 with 1 led.


Set to connect the sonar:bit to P1 with unit “cm” and the PIR sensor to P2, save the returned values as the variable “ultrasonic_distance” and the variable “IR” accordingly.


Judge if the variable “ultrasonic_distance” is in the threshold, if yes, judge if the variable “IR” is 1, if yes, set the strip to show red and the buzzer to alarm; or turn the lights off.


If the variable “ultrasonic_distance” is not in the threshold, program to turn off it light.


Link: https://makecode.microbit.org/_gDhV67AceFJw

5.8. Result

  • If the device detects any people coming to the farmlands, the red light turns on and the buzzer alarms.