Particle Photon and DHT11 - Publish temperature and humidity data

temp-humidity-broadcast.ino

// requires the DHT11 arduino library - https://playground.arduino.cc/Main/DHT11Lib
#include "dht11.h"
#include "Particle.h"

dht11 DHT11;

// pin 2 is used as the data pin to communicate with the DHT11 board
#define DHT11PIN 2

// how long between measurements
long delayTime = 1800000; // 1/2 hour delay
// variable to store the time at start of counting
unsigned long startMillis;

void setup() {
    // get starting time value
    startMillis = millis();
    // take initial reading
    takeReading();
}

void clearCounter() {
    startMillis = millis();
}

// function to take reading from DHT11
void takeReading() {
    // get initial reading to check status of board
    int chk = DHT11.read(DHT11PIN);
    // some debug outputs
    Particle.publish("DEBUG", "Read sensor: ");
    switch (chk)
    {
    case DHTLIB_OK: 
        Particle.publish("DEBUG", "OK");
    	break;
    case DHTLIB_ERROR_CHECKSUM: 
        Particle.publish("DEBUG", "Checksum error");
    	break;
    case DHTLIB_ERROR_TIMEOUT: 
    	Particle.publish("DEBUG", "Time out error");
    	break;
    default: 
    	Particle.publish("DEBUG", "Unknown error");
    	break;
    }
    
    // the board requires a short delay to fetch the data
    delay(1000);
    // take readings and publish the results to particle's server
    Particle.publish("TempHumidityReading", "Temperature: " + String(DHT11.temperature + 1) + "°C, Humidity: " + String(DHT11.humidity) + "%");
}


void loop() {
    // non-blocking timer loop
    // cant do a normal delay here as the Photon doesn't like it
    // when you block it from talking to the server for more than 10 seconds
    if (millis() - startMillis >= delayTime) {
        // if delayTime as elapsed, clear counter and take readings
        clearCounter();
        takeReading();
    }
    
    delay(1000);
}