PIR sensors are used to detect motion from pets/humanoids from about 5 meters away (possibly works on zombies, not guaranteed). This sensor is much smaller than most PIR modules, which makes it great for unobtrusive projects. It's also fully-contained - only needs power and ground, and it's breadboard or perfboard friendly.
Usage is super simple: You can power it from 3 to 12V DC, there's an onboard regulator. Digital signal output is 3.3V high/low. The signal goes high when motion is detected, and stays high for another 2 seconds, so you have plenty of time to read the value.
- Connect pin #1 to ground (there's a tiny minus - sign next to the pin)
- Connect pin #2 to output signal (there's a tiny O next to this pin that goes high and low)
- Connect pin #3 to power (there's a tiny plus + sign next to the pin)
The attached 13.8mm diameter lens is focused to 2 to 5 meters away with a 100-degree spread. These are smaller and less expensive than our PIR modules, and you'll find the performance is OK but not as great as the larger modules, for example not having as wide of a range and taking longer to trigger.
PIR sensors and the Raspberry Pi sometimes don't get along - if you're having false trigger reports, make sure the PIR Sensor is far away from the Pi