Author Sid | Last edit 10/02/2024 by Disisid
ESP32_DHT22_IFTTT_306268167_427924746149632_7414040424516888266_n.jpg Creation
Introduction & Goals:
This project utilizes the Wifi module on an ESP32 along with the Publish/Subscribe (PubSub) library on the Arduino IDE to communicate with other Internet of Things (IoT) devices. In this specific tutorial, we learn how to use the ESP32 to communicate with your personal device in a bidirectional way.
GOALS:
Before we begin, we need to ensure you have an MQTT broker to communicate and test with. We can download MQTTX (the front-end broker) to ensure communication. MQTT is a lightweight messaging protocol designed for efficient communication between devices in low-bandwidth, high-latency networks. It uses a publish-subscribe model, which we will go over later.
Ensure that the ESP32 dev library is installed, then go to libraries in the Arduino IDE and download PubSubClient. PubSub, short for Publish/Subscribe, is a messaging pattern where senders (publishers) distribute messages to receivers (subscribers) without directly communicating with them. Publishers send messages to a central hub (broker), which then distributes them to all interested subscribers based on their topic subscriptions. This is useful to conserve data when trying to share information, because rather than multiple different connections between the publisher and each subscriber, the publisher only needs to send the information once.
Copy the full code into your IDE. Feel free to change things like the text it prints, etc
1 #include <WiFi.h>
2 #include <PubSubClient.h>
3
4 // WiFi
5 const char *ssid = "xxxxx"; // Enter your Wi-Fi name
6 const char *password = "xxxxx"; // Enter Wi-Fi password
7
8 // MQTT Broker
9 const char *mqtt_broker = "broker.emqx.io";
10 const char *topic = "emqx/esp32";
11 const char *mqtt_username = "emqx";
12 const char *mqtt_password = "public";
13 const int mqtt_port = 1883;
14
15 WiFiClient espClient;
16 PubSubClient client(espClient);
17
18 void setup() {
19 // Set software serial baud to 115200;
20 Serial.begin(115200);
21 // Connecting to a WiFi network
22 WiFi.begin(ssid, password);
23 while (WiFi.status() != WL_CONNECTED) {
24 delay(500);
25 Serial.println("Connecting to WiFi..");
26 }
27 Serial.println("Connected to the Wi-Fi network");
28 //connecting to a mqtt broker
29 client.setServer(mqtt_broker, mqtt_port);
30 client.setCallback(callback);
31 while (!client.connected()) {
32 String client_id = "esp32-client-";
33 client_id += String(WiFi.macAddress());
34 Serial.printf("The client %s connects to the public MQTT broker\n", client_id.c_str());
35 if (client.connect(client_id.c_str(), mqtt_username, mqtt_password)) {
36 Serial.println("Public EMQX MQTT broker connected");
37 } else {
38 Serial.print("failed with state ");
39 Serial.print(client.state());
40 delay(2000);
41 }
42 }
43 // Publish and subscribe
44 client.publish(topic, "Hi, I'm ESP32 ^^");
45 client.subscribe(topic);
46 }
47
48 void callback(char *topic, byte *payload, unsigned int length) {
49 Serial.print("Message arrived in topic: ");
50 Serial.println(topic);
51 Serial.print("Message:");
52 for (int i = 0; i < length; i++) {
53 Serial.print((char) payload[i]);
54 }
55 Serial.println();
56 Serial.println("-----------------------");
57 }
58
59 void loop() {
60 client.loop();
61 }
Hi, I'm MQTTX
to the ESP32.
en none 0 Draft
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