HC-SR501 passive infrared sensor

Posted: May 3, 2013 in Robotics, Sensors, Tips and tricks
Tags: , ,

I recently purchased a passive infrared sensor module through e-bay for around 1.7$. I went through few blogs and figured out how it is working. It is pretty straight forward. So this is just a quick guide to anyone who wishes to use the module for the first time.

How it looks…

DSC04711  DSC04713



Delay time:

This is a variable resistor. The minimum delay time is somewhere around 3 seconds. What this means is that there will be 3 seconds time interval in-between two motion detections.


You can turn this variable resistor and change the sensor range. According to the datasheets it is between 3m and 7m.

Continuous trigger:

When the jumper is connected to the continuous trigger position the output will be high as long as the object is moving near the sensor. Once it leaves the sensors detecting area it will transfer from high to low.

Single trigger:

This will make the output high when there is a movement in the detection zone and will drive output low after around 2.5 seconds. Then it will start the process all over again. The sensor will not continuously track the motion in this mode.


Supple 5Vdc to this pin.


Connect the ground to this pin.


This pin will be 3.3V when a motion is detected and it will be ‘0’ when there is no motion.

Test setup…

Note that when the device is first powered up it needs around 1 minute to warm up before starting the sensing process.


After connecting the above simple setup in a bread board you can easily observe that when you move your hand in-front of the sensor the LED will lit up. Change the position of the jumper and the variable resistors and observe there effect on the output in order to get a better understanding of the operation.

Thank you.


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