motion-detection.ino

/*
A Photon sketch for detecting motion. 

This sketch will fire an event when motion is detected, and when it is lost.
The motion timeout is done by the PIR sensor.
*/
const int LED = D7;
const int PIR1 = D4;
const int PIR2 = D5;

const int TTL = 60; // this doesn't actually do anything, but is required.

// The minimum interval between consectutive events of the same type
const int PUBLISH_EVENT_MIN_INTERVAL = 30; // seconds

const int MOTION_DETECTED = 2;
const int MOTION_TIMEOUT = 1;

int lastPirReading = -1;

int lastPublishedAt = 0;
int lastPublishedEventType = 0;

void setup() {
    pinMode(LED, OUTPUT);
    pinMode(PIR1, INPUT);
    pinMode(PIR2, INPUT);
}

void loop() {
    int reading = pirReading();
    if (reading != lastPirReading) {
        if (reading == HIGH) {
            motionDetected();
        } else {
            motionTimeout();
        }
        lastPirReading = reading;
    }
}

int pirReading() {
    int pir1Reading = digitalRead(PIR1);
    int pir2Reading = digitalRead(PIR2);
    
    if (pir1Reading == HIGH || pir2Reading == HIGH) {
        return HIGH;
    } else {
        return LOW;
    }
}

void motionDetected() {
    digitalWrite(LED, HIGH);
    
    publish(MOTION_DETECTED);
}

void motionTimeout() {
    digitalWrite(LED, LOW);
    
    publish(MOTION_TIMEOUT);
}

bool canPublish(int eventType) {
    if (eventType != lastPublishedEventType) {
        return true;
    } else {
        int currentTime = Time.now();
        return (currentTime - lastPublishedAt) > PUBLISH_EVENT_MIN_INTERVAL;
    }
}

bool publish(int eventType) {
    if (canPublish(eventType)) {
        String name = eventName(eventType);
        
        bool success = Particle.publish(name, NULL, TTL, PRIVATE);
        if (success) {
            lastPublishedAt = Time.now();
            lastPublishedEventType = eventType;
        }
        return success;
    }
    return false;
}

String eventName(int eventType) {
    String name = "error";
    switch (eventType) {
        case MOTION_TIMEOUT:
            name = "motion-timeout";
            break;
        case MOTION_DETECTED:
            name = "motion-detected";
            break;
    }
    return name;
}