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PIR Motion Sensor Module

img_pir

The PIR (Passive Infrared) sensor detects infrared radiation, enabling it to sense the presence of organisms that emit heat.

The sensor is divided into two slots connected to a differential amplifier. When a stationary object is in front of the sensor, both slots receive an equal amount of infrared radiation, resulting in zero output. However, when a moving object passes in front of the sensor, one slot detects more radiation than the other. This imbalance causes the output to fluctuate between high and low. These fluctuations in output voltage indicate motion detection.

img_PIR_working_principle

After the sensing module is wired, there is a one-minute initialization. During the initialization, module will output for 0~3 times at intervals. Then the module will be in the standby mode. Please keep the interference of light source and other sources away from the surface of the module so as to avoid the misoperation caused by the interfering signal. Even you’d better use the module without too much wind, because the wind can also interfere with the sensor.

img_pir_back

Distance Adjustment

Turning the knob of the distance adjustment potentiometer clockwise, the range of sensing distance increases, and the maximum sensing distance range is about 0-7 meters. If turn it anticlockwise, the range of sensing distance is reduced, and the minimum sensing distance range is about 0-3 meters.

Delay adjustment

Rotate the knob of the delay adjustment potentiometer clockwise, you can also see the sensing delay increasing. The maximum of the sensing delay can reach up to 300s. On the contrary, if rotate it anticlockwise, you can shorten the delay with a minimum of 5s.

Two Trigger Modes

Choosing different modes by using the jumper cap.

  • H: Repeatable trigger mode, after sensing the human body, the module outputs high level. During the subsequent delay period, if somebody enters the sensing range,the output will keep being the high level.

  • L: Non-repeatable trigger mode, outputs high level when it senses the human body. After the delay, the output will change from high level into low level automatically.

Example