NODE MCU ESP12E V2 and 3x DS18B20 Sensors Send Data to HomeAssistant

ESP with DS18b20 data logger.

• NODE MCU ESP12-F (or something like that)
• DS18B20 sensors (how much do you need?, I have 3pcs.)
• resistor 4k7
• microUSB to USB cable, PC, USB 5V charger
• ArduinoIDE

...and a little patience and skill :)

• the resistor (4k7) is connected between red and yellow cables
• yellow data cable is connected to D2 (pin)
• red is for 3.3V
• black is GND

This is the code that is compiled according to the needs of my project. I drew from official sources but also from other similar projects. Please note, this may not be 100% suitable for everyone.

#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <OneWire.h>
#include <DallasTemperature.h>

#define ONE_WIRE_BUS 2
#define TEMPERATURE_PRECISION 9

#define wifi_ssid "your wifi"
#define wifi_password "youf wifi pass"

#define mqtt_server "IP MQTT server"
#define mqtt_user "MQTT user"
#define mqtt_password "MQTT pass"

#define temperature_topic1 "sensor/temperature1"
#define temperature_topic2 "sensor/temperature2"
#define temperature_topic3 "sensor/temperature3"

#define ONE_WIRE_BUS 2
#define TEMPERATURE_PRECISION 9

OneWire oneWire(ONE_WIRE_BUS);

DallasTemperature sensors(&oneWire);

//address to DS18B20 sensors
DeviceAddress Sensor1 = { 0x28, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
DeviceAddress Sensor2   = { 0x28, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
DeviceAddress Sensor3   = { 0x28, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };

WiFiClient espClient;
PubSubClient client(espClient);


void setup() {
  Serial.begin(115200);

  delay(10);
  
  sensors.begin();
  
  setup_wifi();
  client.setServer(mqtt_server, 1883);

  Serial.println();
  Serial.println();
  Serial.print("Locating DS18B20 sensors...");
  Serial.print("I found ");
  Serial.print(sensors.getDeviceCount(), DEC);
  Serial.println(" devices.");

  Serial.print("Parasite power is: ");
  if (sensors.isParasitePowerMode()) Serial.println("ON");
  else Serial.println("OFF");

  if (!sensors.getAddress(Sensor1, 0)) Serial.println("Unable to find Sensor 1");
  if (!sensors.getAddress(Sensor2, 1)) Serial.println("Unable to find Sensor 2");
  if (!sensors.getAddress(Sensor3, 2)) Serial.println("Unable to find Sensor 3");
  
  sensors.setResolution(Sensor1, TEMPERATURE_PRECISION);
  sensors.setResolution(Sensor2, TEMPERATURE_PRECISION);
  sensors.setResolution(Sensor3, TEMPERATURE_PRECISION);

  Serial.print("Sensor 1 Adress = ");
  printAddress(Sensor1);
  Serial.print(" read temperature: ");
  Serial.print(sensors.getTempC(Sensor1));
  Serial.print(" ºC, Resolution: ");
  Serial.print(sensors.getResolution(Sensor1), DEC);
  Serial.println();

  Serial.print("Sensor 2 Adress = ");
  printAddress(Sensor2);
  Serial.print(" read temperature: ");
  Serial.print(sensors.getTempC(Sensor2));
  Serial.print(" ºC, Resolution: ");
  Serial.print(sensors.getResolution(Sensor2), DEC);
  Serial.println();

  Serial.print("Sensor 3 Adress = ");
  printAddress(Sensor3);
  Serial.print(" read temperature: ");
  Serial.print(sensors.getTempC(Sensor3));
  Serial.print(" ºC, Resolution: ");
  Serial.print(sensors.getResolution(Sensor3), DEC);
  Serial.println();
}

void printAddress(DeviceAddress deviceAddress)
{
  for (uint8_t i = 0; i < 8; i++)
  {
    if (deviceAddress[i] < 16) Serial.print("0");
    Serial.print(deviceAddress[i], HEX);
  }
}

void printTemperature(DeviceAddress deviceAddress)
{
 float tempC = sensors.getTempC(deviceAddress);
 if(tempC == DEVICE_DISCONNECTED_C) 
  {
    Serial.println("!!! Sensor is not connected !!!");
    return;
  }
 Serial.print("Temp C: ");
 Serial.println(tempC);
}

void setup_wifi() {
  delay(10);
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(wifi_ssid);

  WiFi.begin(wifi_ssid, wifi_password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Establishing connection to MQTT server ...");
    if (client.connect("ESP8266Client", mqtt_user, mqtt_password)) {
      Serial.println("connected");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 60 seconds");
      delay(60000);
    }
  }
}

void printData(DeviceAddress deviceAddress)
{
  printTemperature(deviceAddress);
}

bool checkBound(float newValue, float prevValue, float maxDiff) {
  return !isnan(newValue) &&
         (newValue < prevValue - maxDiff || newValue > prevValue + maxDiff);
}

long lastMsg = 0;
float temp1 = 0.0;
float temp2 = 0.0;
float temp3 = 0.0;
float diff = 0.1;

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
  delay(60000);
  
  sensors.requestTemperatures();

  Serial.println("********************************************************");
  Serial.println("Scaned temperature Sensor1:");
  printData(Sensor1);
  Serial.println("Scaned temperature Sensor2:");
  printData(Sensor2);
  Serial.println("Scaned temperature Sensor3:");
  printData(Sensor3);
  Serial.println("********************************************************");
  
  long now = millis();
  if (now - lastMsg > 2000) {
    lastMsg = now;

  float newTemp1 = sensors.getTempC(Sensor1);
  float newTemp2 = sensors.getTempC(Sensor2);
  float newTemp3 = sensors.getTempC(Sensor3);

    if (checkBound(newTemp1, temp1, diff)) {
      temp1 = newTemp1;
      Serial.print("Send temperature Sensor1: ");
      Serial.println(String(temp1).c_str());
      client.publish(temperature_topic1, String(temp1).c_str(), true);
    }
    if (checkBound(newTemp2, temp2, diff)) {
      temp2 = newTemp2;
      Serial.print("Send temperature Sensor2: ");
      Serial.println(String(temp2).c_str());
      client.publish(temperature_topic2, String(temp2).c_str(), true);
    }
    if (checkBound(newTemp3, temp3, diff)) {
      temp3 = newTemp3;
      Serial.print("Send temperature Sensor3: ");
      Serial.println(String(temp3).c_str());
      client.publish(temperature_topic3, String(temp3).c_str(), true);
    }
  }
}

1. install MQTT broker for HA, for example https://learn.adafruit.com/set-up-home-assistant-...
2. configure MQTT broker, paste to config this for three sensors:

mqtt:
  broker: *ip address MQTT server"
  username: *user*
  password: *pass*

sensor 1:
  platform: mqtt
  name: "Temperature1"
  state_topic: "sensor/temperature1"
  qos: 0
  unit_of_measurement: "ºC"

sensor 2:
  platform: mqtt
  name: "Temperature2"
  state_topic: "sensor/temperature2"
  qos: 0
  unit_of_measurement: "ºC"
  
sensor 3:
  platform: mqtt
  name: "Temperature3"
  state_topic: "sensor/temperature3"
  qos: 0
  unit_of_measurement: "ºC"

Maybe you will:

• http://mqtt-explorer.com/
• https://datasheets.maximintegrated.com/en/ds/DS18B...
• in Arduino IDE is fine example to get HEX address DS18B20 sensor

good luck :)