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PIR Sensor (HC-SR501)
Introduction
Passive Infra-Red (PIR) sensors are used to detect motion based on the infrared heat in the surrounding area. This makes them a popular choice when building a system to detect potential intruders or people in general. These sensors can take for 10-60 seconds to warm up, so try to avoid motion during that time.
Parts
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Arduino PIR Sensor Wires
Schematic
Below is the schematic for using a PIR sensor. It is fairly simple.
Code
Adafruit has a really good tutorial for how these sensors are used and various projects for them. Below is the code for working with a PIR sensor. It should be noted that the PIR sensor does not respond immediately when motion stops. This has to do with the two potentiameters on the sensor.
Free Datasheet http://www.
HC-SR501 Datasheet
