(Reference) PIR

PIR - Passive Infrared Sensor

Wiring

Open PIR (Sparkfun)	Photon 2
VCC	3.3v
GND	GND
OUT	Any digital pin
A	(Optional) Any analog pin

Note: The wire color and pin order is specific to the Sparkfun PIR sensor and not all PIR sensors

Wiring Guide

Operation (Sparkfun PIR)

• Requires 1-2 sec delay in setup() to get initial reading from room
• Digital output from AL pin
• HIGH when no movement detected
• LOW when movement detected
• Signal remains active low for about 3 sec after movement (documentation says 15 sec but that doesn’t seem accurate)

Code

This is a basic example where any movement triggers alarm. More sophisticated use can include millis()

const int MOTION_PIN = D2;  // Pin connected to motion detector

void setup() {
    Serial.begin(9600);
    pinMode(MOTION_PIN, INPUT);
    delay(10000);  // wait to read the room
}

void loop() {
    int proximity = digitalRead(MOTION_PIN);
    if (proximity == LOW)  // If the sensor's output goes low, motion is detected
    {
        Serial.println("Motion detected!");
    } else {
        Serial.println("Motion stopped!");
    }
}

Credit

• Sparkfun
• Diagrams created with Frizting