ESP32 and MQTT: Establishing the First Connection and Data Transfer

10.12.2024 - Engine: Gemini

ESP32

The ESP32 is a low-power microcontroller with built-in Wi-Fi and Bluetooth functionality. It is commonly used in Internet of Things (IoT) applications.

Features:

• Dual-Core CPU
• Integrated Wi-Fi and Bluetooth
• Low power consumption
• Compact size

MQTT

MQTT (Message Queuing Telemetry Transport) is a lightweight messaging protocol used in IoT applications. It allows devices to exchange messages through a central broker.

Features:

• Publish-subscribe architecture
• Low bandwidth and storage requirements
• Quality of Service (QoS) levels

Getting Started with ESP32 and MQTT: Connecting and Publishing Data

Materials:

• ESP32 module
• MQTT broker
• Wi-Fi access

Steps:

1. Connect ESP32 to Wi-Fi:

• Connect the ESP32 to a Wi-Fi network.
• Use the WiFi library in the ESP32 firmware.

2. Create MQTT client:

• Create an MQTT client using the PubSubClient library.
• Set the client's broker IP address, port, and credentials.

3. Connect to MQTT broker:

• Connect the client to the MQTT broker.

4. Publish data:

• Publish data to a specific topic.
• Use the publish() function with the topic name and data to be sent as arguments.

5. Receive data:

• Subscribe to a topic on the broker.
• Use the subscribe() function with the topic name as an argument.
• Register a callback function to be called when a message is received.

Example Code:

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

const char* ssid = "Wi-Fi network name";
const char* password = "Wi-Fi password";
const char* broker = "MQTT broker IP address";
const uint16_t port = 1883;
const char* topic = "mytopic";

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
  }
  Serial.println("Connected to Wi-Fi");

  client.setServer(broker, port);
  client.connect("client_id");
  Serial.println("Connected to MQTT broker");
}

void loop() {
  if (!client.connected()) {
    client.connect("client_id");
  }

  client.publish(topic, "Hello, IoT!");
  Serial.println("Data sent");

  client.loop();
}