Connecting an ESP8266-12 to a DS1820 Thermometer and Do a HTTP Post Data to the Internet

Pre-requisites!

I'll be using these components:

• A standard ESP8266-12 on a breakout-board such as the one shown
• Three 4.7k resistors
• A 3v battery (I use a CR123a) for powering the ESP826612
• A DS1820 (I use the DO-92 packaged version below)

The following requirements should be met:

• All connections, including those on the The ESP 8266-12 on the breakout-board, are solid and conduct power as they should.
• The battery holds at least 2.8v of power.
• The ESP8266-12 has been programmed with the following sketch:

  #include OneWire.h
  #include DallasTemperature.h
  #include ESP8266WiFi.h
  #include ESP8266WiFiMulti.h
  #include ESP8266HTTPClient.h
  
  #define ONEWIRE_PIN 13
  
  OneWire oneWire(ONEWIRE_PIN);
  DallasTemperature sensors(&oneWire);
  
  boolean TempSensorAvailable = false;
  DeviceAddress TempSensor;
  float tempCtry1;
  float tempCtry2;
  
  //AP definitions
  #define AP_SSID "your wifi-network name here<your-wifi-network-name-here>"
  #define AP_PASSWORD "wifi password here<your-wifi-network-password-here>"
  
  void setup() {
  
  //enable this to test from the arduino serial monitor
  Serial.begin(74880);
  
  sensors.begin();
  
  Serial.print("Found ");
  Serial.print(sensors.getDeviceCount(), DEC);
  Serial.println(" OneWire device(s).");
  
  // report parasite power requirements
  Serial.print("Parasite power: ");
  if (sensors.isParasitePowerMode()) Serial.println("ON");
  else Serial.println("OFF");
  
  if (!sensors.getAddress(TempSensor, 0)) {
  Serial.println("No OneWire Device Found");
  } else {
  TempSensorAvailable = true;
  Serial.println("OneWire Device Found");
  sensors.setResolution(TempSensor, 12);
  }
  }
  
  void loop() {
  
  wifiConnect();
  postTemperature();
  <onewire .h=""><dallastemperature 
  .h=""><esp8266wifi .h=""><esp8266wifimulti 
  .h=""><esp8266httpclient 
  .h=""><your-wifi-network-name-here><your-wifi-network-password-here>
  <onewire .h=""><dallastemperature 
  .h=""><esp8266wifi .h=""><esp8266wifimulti 
  .h=""><esp8266httpclient 
  .h=""><your-wifi-network-name-here>
  <your-wifi-network-password-here>delay(60 * 1000);
  }
  
  void postTemperature()
  {
  sensors.requestTemperatures();            // Get temprature
  tempCtry1 = sensors.getTempC(TempSensor); // save temperature
  sensors.requestTemperatures();            // Get temprature
  tempCtry2 = sensors.getTempC(TempSensor); // save temprature
  
  HTTPClient http;
  http.begin("http://<your-http-post-endpoint-here>");
  http.addHeader("Content-Type", "application/json");
  String postMessagePart1 = String("{ 'sensorId' : 
  'L15-Out1', 'temperature' : '");
  String postMessagePart2 = String("', 'postAttempts' : '");
  String postMessagePart3 = String("', 'batteryVoltage' : '");
  String postMessagePart4 = String("' }");
  String postMessage = postMessagePart1 + ((tempCtry1+tempCtry2)/2) + 
  postMessagePart2 + retries + postMessagePart3 + vdd + postMessagePart4 ;
  int httpCode = http.POST(postMessage);
  Serial.print("http result:");
  Serial.println(httpCode);
  
  http.writeToStream(&Serial);
  http.end();
  
  if ( httpCode != 200 && httpCode != 201)
  {
  delay(1000);
  postTemperature();
  }
  }
  
  void wifiConnect()
  {
  Serial.print("Connecting to AP");
  WiFi.begin(AP_SSID, AP_PASSWORD);
  while (WiFi.status() != WL_CONNECTED) {
  delay(1000);
  Serial.print(".");
  }
  
  Serial.println("");
  Serial.println("WiFi connected");
  }

Don't forget to import the libraries into the Arduino IDE environment.

Given the above is in order, go ahead and connect the components as per the following picture:

• The RESET and GPIO16 pins should be connected - this enables the ESP 8266-12 to wake up from deep sleep mode.
• The GPIO0 and GPIO2 should be connected to VCC with a 4.7k resistor in the middle. This is to prevent a so-called 'zombie-mode', in which the ESP8266-12 has trouble waking up from deep sleep.
• The data-line and the VCC line of the DS1820 should be joined by a 4.7k resistor, or the temperature will not be read.
• The data-line of the DS1820 should be connected to the GPIO13-pin of the stand-alone ESP8266-12, as this corresponds with the "#define ONEWIRE_PIN 13" statement of the code.

With the ESP connected like so, my ESP8266-12 happily does an HTTP post to my web-service every 60 seconds, before repeating the cycle.

You should put the ESP8266-12 into deep sleep mode if you power your thermometer via battery.