Adafruit Mini Basic PIR Sensor - BL412

PIR sensors detect motion from pets and humanoids within approximately 5 meters, possibly extending even to zombies. This compact design is ideal for discreet projects. Equipped with a fully-contained setup, it requires only power, ground, and a resistor to set the delay time, making it breadboard and perfboard friendly.

Operating on 3.3V power, it’s essential to power it through a 3V regulator when interfacing with a 5V chip like Arduino. The digital signal output is 3.3V high/low, allowing customization of the signal duration via a resistor divider, from 2 seconds (0V) to an hour (3.3V). Consult the datasheet's 'on time' table for recommended resistor values.

Installation is straightforward: Refer to the datasheet's pin-out diagram on page 7. The snap-on lens is optimized to focus up to 5 meters away with a 120-degree spread but should detect motion from about 3 to 8 meters. While smaller and more cost-effective than larger models, these modules deliver satisfactory performance, albeit with a slightly narrower range and a slower triggering response.

The sensor window measures 5mm x 3.8mm. For a smaller sensing element, consider the BS412 PIR sensor. Find tutorials, CircuitPython, and Arduino code examples on our PIR sensor tutorial page.