03-05-2011, 10:20 AM
General Description
The PIR (Passive Infra-Red) Sensor is a pyroelectric device that detects motion by measuring changes in
the infrared levels emitted by surrounding objects. This motion can be detected by checking for a high
signal on a single I/O pin.
Features
Single bit output
Small size makes it easy to conceal
Compatible with all Parallax microcontrollers
3.3V & 5V operation with <100uA current draw
Application Ideas
Alarm Systems
Halloween Props
Quick Start Circuit
Note: The sensor is active high
when the jumper (shown in the
upper left) is in either position.
Theory of Operation
Pyroelectric devices, such as the PIR sensor, have elements made of a crystalline material that generates
an electric charge when exposed to infrared radiation. The changes in the amount of infrared striking the
element change the voltages generated, which are measured by an on-board amplifier. The device
contains a special filter called a Fresnel lens, which focuses the infrared signals onto the element. As the
ambient infrared signals change rapidly, the on-board amplifier trips the output to indicate motion.
Download full report
http://parallaxdl/docs/prod/audiovis/PIRSensor-V1.1.pdf
The PIR (Passive Infra-Red) Sensor is a pyroelectric device that detects motion by measuring changes in
the infrared levels emitted by surrounding objects. This motion can be detected by checking for a high
signal on a single I/O pin.
Features
Single bit output
Small size makes it easy to conceal
Compatible with all Parallax microcontrollers
3.3V & 5V operation with <100uA current draw
Application Ideas
Alarm Systems
Halloween Props
Quick Start Circuit
Note: The sensor is active high
when the jumper (shown in the
upper left) is in either position.
Theory of Operation
Pyroelectric devices, such as the PIR sensor, have elements made of a crystalline material that generates
an electric charge when exposed to infrared radiation. The changes in the amount of infrared striking the
element change the voltages generated, which are measured by an on-board amplifier. The device
contains a special filter called a Fresnel lens, which focuses the infrared signals onto the element. As the
ambient infrared signals change rapidly, the on-board amplifier trips the output to indicate motion.
Download full report
http://parallaxdl/docs/prod/audiovis/PIRSensor-V1.1.pdf
