6. Case 04: Farmlands Protection Device

6.1. Introduction

---

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

6.2. 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.

6.3. Products Link

---

• 1 x microbit Smart Agriculture Kit

6.4. Picture

---

6.5. Hardware Connection

---

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

6.6. 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.

6.7. 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

6.8. Result

---

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