Introduction: ESP32 + DHT11 Weather Monitor for V-VAC Dashboard

By V-VAC IoT Platform
About: Supercharged No-Code IIoT Platform Create, connect, and scale IoT applications in days, not months. V-VAC delivers real time monitoring, device management, and data visualization from one browser window. Wheth…

Want to build your own tiny weather station?

In this DIY guide, we’ll use an ESP32 and a DHT11 sensor to send temperature and humidity straight to the V-VAC IoT dashboard using MQTT.

It’s super simple, beginner-friendly, and a great way to get started with real cloud-connected projects.

Let’s build it!

Supplies

  1. ESP32 Dev Board
  2. DHT11 Temperature/Humidity Sensor module
  3. Jumper wires
  4. Breadboard
  5. A Wi-Fi connection
  6. Your V-VAC MQTT topic (given by V-VAC)

Step 1: Wiring the DHT11

Connect the Esp32 and Sensor according to the connection Diagram.

Step 2: Installing Libraries

  1. WiFi by Arduino // This library is usually built-in, but verify that it is installed.
  2. DHT SENSOR LIBRARY by Adafruit
  3. PubSubClient by Nick O'Leary

Step 3: VVAC Cloud Setup

Steps to Connect V-VAC :

  1. Log in to your V-VAC account. (Create a new account if not signed up already.)
  2. In the Devices section add a new device.
  3. Select common device and enter the details of the device.
  4. Copy the Device Token and paste it in the MQTT section of the code.
  5. Copy the username and password from the setup in devices section and paste it in the MQTT section of the code.

For further details check out (How to connect to V-VAC).

Step 4: Upload the Code

#include <WiFi.h>
#include <PubSubClient.h>
#include <DHT.h>

#define DHT11_PIN 4
DHT dht11(DHT11_PIN, DHT11);

// WiFi Configuration
const char* ssid = "Your_Wifi_SSID"; // eg. ssid = "ssid"
const char* password = "Your_Wifi_Password"; // eg. password = "password"

// MQTT Configuration
const char* mqtt_broker = "data.volkkommen.com";
const int mqtt_port = 1883;
const char* mqtt_username = "Your_MQTT_Username"; // eg. mqtt_username = "mqtt_username"
const char* mqtt_password = "Your_MQTT_Password"; // eg. mqtt_password = "mqtt_password"
const char* device_token = "Your_Device_Token"; // eg. device_token = "6810eb7g27560f46"


WiFiClient espClient;
PubSubClient mqttClient(espClient);

void setupWiFi() {
Serial.println();
Serial.print("Connecting to WiFi: ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
}

void connectMQTT() {
while (!mqttClient.connected()) {
Serial.print("Attempting MQTT connection... ");
if (mqttClient.connect(device_token, mqtt_username, mqtt_password)) {
Serial.println("connected to MQTT broker");
} else {
Serial.print("failed, rc=");
Serial.print(mqttClient.state());
Serial.println(" trying again in 5 seconds");
delay(5000);
}
}
}

String sensor_working() {
// Example data (modify with your sensor/data)
float humi = dht11.readHumidity();
// read temperature in Celsius
float tempC = dht11.readTemperature();
// read temperature in Fahrenheit
float tempF = dht11.readTemperature(true);

// check whether the reading is successful or not
if ( isnan(tempC) || isnan(tempF) || isnan(humi)) {
Serial.println("Failed to read from DHT11 sensor!");
} else {
Serial.print("Humidity: ");
Serial.print(humi);
Serial.print("%");

Serial.print(" | ");

Serial.print("Temperature: ");
Serial.print(tempC);
Serial.print("°C ~ ");
Serial.print(tempF);
Serial.println("°F");
}

// wait a 2 seconds between readings
delay(2000);

String payload = "{\"temperature\":" + String(tempC, 3) + ",\"humidity\":" + String(humi, 3) + "}";
return payload;
}

void publishData() {
String payload = sensor_working();
String topic_p = "data/v1/" + String(device_token);
if (mqttClient.publish(topic_p.c_str(), payload.c_str())) {
Serial.println("Message published successfully " + payload);
} else {
Serial.println("Failed to publish message");
}
}

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

void setup() {
Serial.begin(115200);
dht11.begin();
setupWiFi();
mqttClient.setServer(mqtt_broker, mqtt_port);
}

void loop() {
if (WiFi.status() != WL_CONNECTED) { // Maintain WiFi connection
setupWiFi();
}

if (!mqttClient.connected()) { // Maintain MQTT connection
connectMQTT();
}
mqttClient.loop();
static unsigned long lastPublishTime = 0; // Publish data every 2 seconds
if (millis() - lastPublishTime >= 2000) {
publishData();
lastPublishTime = millis();
}
}

Step 5: View Live Data in V-VAC

  1. In Dashboard section you can configure widgets for your required data.
  2. Click “Create Dashboard”.
  3. Give your dashboard a name (e.g., Door Status Dashboard).
  4. Click the 3rd icon in the dashboard to open the dashboard.
  5. Inside the dashboard editor, click “Edit” and click "Add Widget" to add new widgets.
  6. In the selection menu choose the required widget.
  7. Link widget to a Device telemetry key (the data your device sends).
  8. After customizing your widget, click the Show on Dashboard button to display it on the dashboard.
  9. To save your changes, click the Save button at the top-right corner of the dashboard.
  10. You can now remotely see the Door status from anywhere around the world.

For more IoT projects and tutorials, visit the official V-VAC Platform - V-VAC.