ESP32 Starter Kit
5. Test Result
After connecting the wiring and uploading code, press blue button to add time, green to reduce and red to reset. Press
yellow button for counting down. When it is over, the bomb explodes.
9.2.20 Project 17: Invasion Alarm
1. Description
This invasion alarm system is able to detect invaders in houses or small offices and warn the host to take measures in
time.
In this project, the sensor monitors a certain area. Some device on Arduino board will trigger LED to light up and
buzzer to beep for caution if a movement is detected in that zone. What’s more, its sensibility is adjustable for a more
accurate detection.
Virtually, this module features practicability, easy installation and low costs. With the exception of home and office, it
also applies to factories, warehouses and markets, which, to a large extent, protects property security.
2. Working Principle
Human body(37°C) always emits infrared ray with a wavelength of 10m, which approximates to that of the sensor
detected. On this account, this module is able to detects human beings movement. If there is, PIR sensor outputs a
high level about 3s and, it outputs a low level.
256 Chapter 9. Scratch Tutorial
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