Description
Passive Infra-Red (PIR) sensor is a motion detector sensor by measures changes in the infrared levels emitted by surrounding objects. It gives a HIGH signal at the I/O pin when motion is detected. Usually used as a security device in a monitored area (such as a room or hall) to detect the appearance of a human being.
Features:
- Passive infrared sensor (PIR sensor)
- Operating voltage: DC 4.5V ~ 5V
- Quiescent Current: <65uA
- Output: High level 3.3 V; Low level 0V
- Delay time: 5-200S(adjustable)
- Trigger mode setting: L=Not repeated(default); H=Repeated
- Block time 2.5S(default)
- Board Dimensions 32mm x 24mm
- Sensing Angle: < 120° cone angle
- Operation Temp. -15 ~ +70 degrees
How the PIR Sensor Work
- The PIR sensor itself has two slots in it, each slot is made of a special material that is sensitive to IR.
- When the sensor is idle, both slots detect the same amount of IR, the ambient amount radiated from the room or walls or outdoors.
- When a warm body like a human or animal passes by, it first intercepts one half of the PIR sensor, which causes a positive differential change between the two halves. When the warm body leaves the sensing area, the reverse happens, whereby the sensor generates a negative differential change. These change pulses are what is detected
- The IR sensor itself is housed in a hermetically sealed metal can to improve noise immunity.
There is a window made of IR-transmissive material (typically coated silicon since that is very easy to come by) that protects the sensing element. Behind the window are the two balanced sensors
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