Motion object detection during day or night with using PIR (Passive infrared sensor) and Ultrasound (Sonar) sensor on microcontroller – part I

I’d like to present my new project basing on raw microcontroller in object detection during day or night with using PIR (Infrared) and Ultrasound (Sonar) sensor. Additionally microcontroller calculates the distance to the detected object. System can be applied in many areas: to monitor house or like in my case to automatic open little door for my cats at night. Soon will be applied by me neural network on Atmel AVR controller. Source code is written in C language – and bases on Atmel AVR controller.

Operating principles:
1. After starting microcontroller – system is disarmed at the begining.
2. By clicking button user can armed / disarmed system.
3. After armed system green diode is switch-on. User has 5 seconds on leave monitored area (time can be changing).
After 5 second when system detects motion of object then red diode is switch-on and starts running sound alarm
When system is disarmed green diode is switch-off, system doesn’t monitoring object

  1. A. Detection based on echolocation

Sonar bases on echolocation technique. Bats use a variety of ultrasonic ranging (echolocation) techniques to detect their prey. They can detect frequencies beyond 100 kHz, possibly up to 200 kHz.

Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from “normal” (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is approximately 20 kilohertz (20,000 hertz) in healthy young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz.

Ultrasound is used in many different fields. Ultrasonic devices are used to detect objects and measure distances. Ultrasound imaging or sonography is often used in medicine. In the nondestructive testing of products and structures, ultrasound is used to detect invisible flaws. Industrially, ultrasound is used for cleaning, mixing, and accelerating chemical processes. Animals such as bats and porpoises use ultrasound for locating prey and obstacles.

B. Passive infrared sensor

A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors. PIR sensors are commonly used in security alarms and automatic lighting applications.

PIR sensors detect general movement, but do not give information on who or what moved. For that purpose, an active IR sensor is required.

PIR sensors are commonly called simply “PIR”, or sometimes “PID”, for “passive infrared detector”. The term passive refers to the fact that PIR devices do not radiate energy for detection purposes. They work entirely by detecting infrared radiation(radiant heat) emitted by or reflected from objects.


February 18th, 2020