Mini Basic PIR Sensor - BL412

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, ground and a resistor to set the delay time - and breadboard or perfboard friendly.

Runs on 3.3V power - so make sure if you're interfacing with an Arduino or other 5V chip, you power it from the 3V regulator. Digital signal output is 3.3V high/low and you can change the length of time the signal pin stays high by connecting a resistor divider to the second pin, from 2 seconds (0V) up to one hour (3.3V) - see the datasheet 'on time' table for recommended resistor values.

To use, see datasheet page 7 pin-out diagram:

• Connect pin #1 to ground
• Connect pin #2 to ground (on time of 2 seconds)
• Connect pin #3 to 3.3V
• Check signal on pin #4

The snap-on lens is focused to 5 meters away with a 120 degree spread, but should work from about 3 to 8 meters.

For a PIR tutorial with CircuitPython and Arduino code examples and project ideas, check out our PIR sensor tutorial page!