ESP32-MQTT

ESP32-MQTT

Aim:

To interface Wi-Fi module with ESP32 to receive data from cloud using RDL ESP32 Development board.

Description:

Interfacing wi-fi module with the cloud MQTT to receive and send data using ESP32 microcontroller.

Hardware required:

ESP32-Microcontroller development board.

Pin connection:

Procedure:

Uploading and Receiving Data from Cloud using ESP32

1.        Create an Account in www.cloudmqtt.com

2.        Create an instance which will be used in the program to publish data to the cloud.

3.    Select the Instance name (test_1) and use the details of the same in the code. Include the code.

5.        Enter the details given under server, port, user, ssl port in the given program.

const char* mqttServer =”m16.mqtt.com”; const int mqttPort = 18215;

const char* mqttUser = “ofmydmjh”;;

const char* mqttPassword = “c5goIEjTCGRn”;

6.        In order to send a message to the CloudMQTT, include the line client.publish("topic_name", "Message");

7.        To send data from CloudMQTT ,include the line client.subscribe("Topic_name");\

5.        8. The following code prints the received data from the cloud in the Serial Monitor                      void callback(char* topic, byte* payload, unsigned int length)

{

uint8_t s;

Serial.print("Message arrived in topic: "); 

Serial.println(topic); Serial.print("Message:");

for (int i = 0; i < length; i++)

{

s= payload[i]; 
Serial.write(s);

}

}

5.        The final Program:

#include <WiFi.h>

#include <PubSubClient.h> const char* ssid = "userid";

const char* password = "*********";

/* Details from the instance created */

const char* mqttServer = "m16.cloudmqtt.com"; const int mqttPort = 18215;

const char* mqttUser = "ofmydmjh";

const char* mqttPassword = "c5g0IEjTCGRn"; WiFiClient espClient;

PubSubClient client(espClient); void setup(void)

{

Serial.begin(115200); WiFi.begin(ssid, password);

/* Connecting ESP8266 to WiFi */

while (WiFi.status() != WL_CONNECTED)

{

delay(500);

Serial.write('.');

}

Serial.println("Connected to the WiFi network"); client.setServer(mqttServer, mqttPort); client.setCallback(callback);

/* Connecting to CloudMqtt */ while (!client.connected())

{

Serial.println("Connecting to MQTT...");

if (client.connect("ESP32Client", mqttUser, mqttPassword ))

{

Serial.println("connected");

}

else

{

Serial.print("failed with state "); Serial.print(client.state()); delay(2000);

}

}

/* Sending message to Topic "test1" */ client.publish("ABC", "Hello from RDL_IOT");

client.subscribe("test"); //Receives message sent to the topic "test"

}

/* This function is used to print the incoming data sent to the topic "test" */ void callback(char* topic, byte* payload, unsigned int length)

{

uint8_t s;

Serial.print("Message arrived in topic: "); Serial.println(topic); Serial.print("Message:");

for (int i = 0; i < length; i++)

{

s= payload[i];

Serial.write(s);

}

}

void loop(void)

{

client.loop();

}

Output: