How to use the photon ds18b20

I am currently living in reunion island (between Madagascar and Mauritius) with my wife and a little rabbit! As the climate is tropical (very warm and humid) I wanted to be able to know my home’s temperature from my office using one of my Photon and a Dallas ds18b20 temperature sensor.

Requirements

First of all you need :

• A Photon
• A bread board
• A 4.7kOhm resistor (in my example I use two 10kOhm in parallel, so ~5kOhm)
• A Dallas ds18b20 temperature sensor
• Some jumper wires

Schematics

Firmware

// This #include statement was automatically added by the Particle IDE.
#include "application.h"
#include "OneWire/OneWire.h"
#include "spark-dallas-temperature/spark-dallas-temperature.h"

// ---------------------
// TEMPERATURE
// Init the tempC variable
// ---------------------
double tempC = 0;

// ---------------------
// ONEWIRE + DALLAS
// ---------------------
// Set the oneWire bus to pin 4
#define ONE_WIRE_BUS 4
// Setup a oneWire instance to communicate with any OneWire devices
OneWire oneWire(ONE_WIRE_BUS);
// Pass the oneWire reference to Dallas Temperature.
DallasTemperature sensors(&oneWire);

void setup() {
  // VARS
  // ---------------------
  // Init the tempC variable with the Particle method
  Particle.variable("tempC", &tempC, DOUBLE);

  // INIT Serial for terminal checking
  // ---------------------
  Serial.begin(9600);

  // INIT Sensors
  // ---------------------
  // Start up the library
  Serial.println("Dallas Temperature IC Control Library");
  sensors.begin();
}

void loop() {
  // ---------------------
  // TEMPERATURE
  // ---------------------
  // call sensors.requestTemperatures() to issue a global temperature
  // request to all devices on the bus
  Serial.println(" Requesting temperatures...");

  // Send the command to get temperatures
  sensors.requestTemperatures();
  Serial.println("DONE");

  Serial.println("Temperature for Device 1 is: ");
  tempC = sensors.getTempCByIndex(0);
  Serial.println(tempC);

  // Why "byIndex"?
  // You can have more than one IC on the same bus.
  // 0 refers to the first IC on the wire

  // ---------------------
  // DELAY
  // ---------------------
  delay(10000);
}

Reading the temperatures

You can now have access to your home’s temperature with the Particle cloud api :

http://api.particle.io/v1/devices/YOUR_PHOTON_ID/tempC?access_token=YOUR_ACCESS_TOKEN

Conclusion

I admit this setup is not doing much on its own, but I hope it will help some of you to getting started with your Photon and to have fun doing this.