ESP32 - Read DHT11 Temperature and humidity and publish to MQTT Broker

ESP32 - Read DHT11 Temperature and humidity and publish to MQTT Broker

[TheKverbeeck]

Follow the guide below for the Raspberry pi Mosquitto set-up:

[TheKverbeeck]

ESP32 code: Adapt the "x" to match your set-up

// Include the necessary libraries
#include <DHT.h> // DHT11 sensor
#include <WiFi.h> // Wi-Fi Client
#include <ESP32Ping.h> // Ping Client for testing
#include <PubSubClient.h> // MQTT Client
#include <Wire.h> // I2C bus

/*
DHT11 Sensor (Temperature and Humidity)
*/
#define DHTPIN 26 // for ESP32
#define DHTTYPE DHT11 // DHT11 or DHT22

DHT dht(DHTPIN, DHTTYPE);

/*
MQTT client - ESP32
*/
const char* ssid = // Wi-Fi SSID
const char* password = // Wi-Fi password

//const char* dht11_topic = "home/RPi3B"; // MQTT Topic for Subscribing

const char* mqttServer = // MQTT Broker
const int mqttPort = 1883; // MQTT Port
const char* mqttUser = // Username Mosquitto
const char* mqttPassword = // Password Mosquitto
const char* clientID = // MQTT client ID

WiFiClient espClient;
PubSubClient client(espClient);

const IPAddress remote_ip(x, x, x, x); // IP address of MQTT Broker for ping

void setup_wifi() {
// Delay for 10ms
delay(10);
// Print an empty line
Serial.println();
// Print to which SSID ESP32 is trying to connect
Serial.print(F("Connecting to "));
Serial.println(ssid);

// Initialize Wi-Fi on ESP32 and connect to the configured WLAN
WiFi.begin(ssid, password);

// As long as ESP32 is not connected to the configured WLAN
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.println(F("Trying to Connect"));
}
Serial.print(F("\nConnected to the "));
Serial.print(ssid);
Serial.println(F(" Wi-Fi network\n"));
}

void RSSI_Info() {
// Request Wi-Fi Signal Strength 3 times
for (int i = 0; i < 3; i++) {
Serial.print(F("RSSI: "));
Serial.print(WiFi.RSSI());
Serial.println(F("dBm"));
delay(1000);
}
Serial.println();
}

void ping_MQTT_Broker() {
// Send 3 pings to the MQTT Broker
Serial.print(F("Pinging MQTT Broker 2 times: "));
Serial.println(remote_ip);
for (int i = 0; i < 2; i++) {
if (Ping.ping(remote_ip)) {
Serial.print(F("Success >> "));
// prints ping delay
Serial.println(F("ms"));
}
else {
Serial.println(F("No reply"));
}
}
Serial.println();
}

void DHCP_Info() {
// Print the ESP32 IP info received from DHCP
Serial.print(F("IP address: "));

Serial.print(F("Subnet Mask: "));

Serial.print(F("Default Gateway: "));

Serial.println();
}

//// Callback function when an MQTT message is received
//void callback(char* topic, byte* payload, unsigned int length) {
// Serial.print("Message arrived in topic: ");
// Serial.println(topic);
//
// //Serial.print("Message:");
// //for (int i = 0; i < length; i++) {
// //
// //}
//
//
//
// if ((char)payload[0] == '1') {
// digitalWrite(whiteLight, HIGH);
// }
// else {
// digitalWrite(whiteLight, LOW);
// }
//
// Serial.println();
//
//}



void setup() {

Serial.begin(115200);

/*
DHT11 Sensor (Temperature and Humidity)
*/
dht.begin();

/*
Initialize MQTT client - ESP32
*/
setup_wifi();
RSSI_Info();
DHCP_Info();
ping_MQTT_Broker();
client.setServer(mqttServer, mqttPort);

// // set a callback function for when data is received from broker
// client.setCallback(callback);

// connect to broker
while (!client.connected()) {
Serial.println("Connecting to MQTT...");
if (client.connect("ESP32Client", mqttUser, mqttPassword )) {
Serial.println("connected");
}
else {
/*
int state ()
Returns the current state of the client. If a connection attempt fails,
this can be used to get more information about the failure.

All of the values have corresponding constants defined in PubSubClient.h.

Returns:
-4 : MQTT_CONNECTION_TIMEOUT - the server didn't respond within the keepalive time
-3 : MQTT_CONNECTION_LOST - the network connection was broken
-2 : MQTT_CONNECT_FAILED - the network connection failed
-1 : MQTT_DISCONNECTED - the client is disconnected cleanly
0 : MQTT_CONNECTED - the client is connected
1 : MQTT_CONNECT_BAD_PROTOCOL - the server doesn't support the requested version of MQTT
2 : MQTT_CONNECT_BAD_CLIENT_ID - the server rejected the client identifier
3 : MQTT_CONNECT_UNAVAILABLE - the server was unable to accept the connection
4 : MQTT_CONNECT_BAD_CREDENTIALS - the username/password were rejected
5 : MQTT_CONNECT_UNAUTHORIZED - the client was not authorized to connect
*/
Serial.print("failed with state ");

delay(2000);
}
}
// // subscribe to topic
//
}

void loop() {

/*
MQTT client - ESP32
*/
client.loop();

/*
DHT11 Sensor (Temperature and Humidity)
*/
float humidity = dht.readHumidity();
float temperature = dht.readTemperature();

// check if returns are valid and print the sensor data
if (isnan(temperature) || isnan(humidity)) {
Serial.println("Failed to read from DHT");
}
else {
Serial.print("Temperature: ");
Serial.print(temperature - 2); // Temperature correction
Serial.println("°C");
Serial.print("Humidity: ");
Serial.print(humidity);
Serial.println("%");
}

// Convert float (temperature) to char array
// Must be at least 10 char for the float payload
// "home/esp32/dht11_temp"
char temp_array[10];
sprintf(temp_array, "%f", temperature - 2); // Temperature correction
// Convert float (humidity) to char array
// Must be at least 10 char for the float payload
// "home/esp32/dht11_humi"
char humi_array[10];
sprintf(humi_array, "%f", humidity);

// Only publish data if the sensor is sending actual data (connected)
if (not(isnan(temperature) || isnan(humidity))) {
client.publish("home/esp32/dht11_temp", temp_array);
client.publish("home/esp32/dht11_humi", humi_array);
}

// client.disconnect(); // disconnect from the MQTT broker
// Serial.println("Disconnecting from MQTT...");
delay(1000 * 2); // Wait for 2 seconds
}