Hi here a small tutorial of how to connect the ESP32 with HIVEMQ and use NODE-RED as a dashboard / visualiser.
First here a template code (that work flawlessly for me):Just replace the XXXX with your input/value
make sure you install the needed library.
#include <WiFi.h>
#include <PubSubClient.h>
#include <WiFiClientSecure.h>
//---- WiFi settings
const char* ssid = “XXXX”;
const char* password = “XXXX”;
//---- MQTT Broker settings
const char* mqtt_server = “XXXX”; // replace with your broker url
const char* mqtt_username = “XXXX”;
const char* mqtt_password = “XXXX”;
const int mqtt_port =8883;
WiFiClientSecure espClient;
PubSubClient client(espClient);
unsigned long lastMsg = 0;
#define MSG_BUFFER_SIZE (50)
char msg[MSG_BUFFER_SIZE];
const char* sensor1_topic= “sensor1”;
const char* sensor2_topic=“sensor2”;
static const char *root_ca PROGMEM = R"EOF(
-----BEGIN CERTIFICATE-----
MIIFazCCA1OgAwIBAgIRAIIQz7DSQONZRGPgu2OCiwAwDQYJKoZIhvcNAQELBQAw
TzELMAkGA1UEBhMCVVMxKTAnBgNVBAoTIEludGVybmV0IFNlY3VyaXR5IFJlc2Vh
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MTCCAiIwDQYJKoZIhvcNAQEBBQADggIPADCCAgoCggIBAK3oJHP0FDfzm54rVygc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HRMBAf8EBTADAQH/MB0GA1UdDgQWBBR5tFnme7bl5AFzgAiIyBpY9umbbjANBgkq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=
-----END CERTIFICATE-----
)EOF";
void setup() {
Serial.begin(9600);
Serial.print("\nConnecting to ");
Serial.println(ssid);
WiFi.mode(WIFI_STA);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(“.”);
}
randomSeed(micros());
Serial.println("\nWiFi connected\nIP address: ");
Serial.println(WiFi.localIP());
while (!Serial) delay(1);
espClient.setCACert(root_ca);
client.setServer(mqtt_server, mqtt_port);
client.setCallback(callback);
}
void loop() {
if (!client.connected()) reconnect();
client.loop();
publishMessage(sensor1_topic,String(XXXX),true);
publishMessage(sensor2_topic,String(XXXX),true);
}
//=======================================================================Function=================================================================================
void reconnect() {
// Loop until we’re reconnected
while (!client.connected()) {
Serial.print(“Attempting MQTT connection…”);
String clientId = “ESP8266Client-”; // Create a random client ID
clientId += String(random(0xffff), HEX);
// Attempt to connect
if (client.connect(clientId.c_str(), mqtt_username, mqtt_password)) {
Serial.println(“connected”);
client.subscribe(command1_topic); // subscribe the topics here
//client.subscribe(command2_topic); // subscribe the topics here
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds"); // Wait 5 seconds before retrying
delay(5000);
}
}
}
//=======================================
// This void is called every time we have a message from the broker
void callback(char* topic, byte* payload, unsigned int length) {
String incommingMessage = “”;
for (int i = 0; i < length; i++) incommingMessage+=(char)payload[i];
Serial.println(“Message arrived [”+String(topic)+“]”+incommingMessage);
// check for other commands
/* else if( strcmp(topic,command2_topic) == 0){
if (incommingMessage.equals(“1”)) { } // do something else
}
*/
}
//======================================= publising as string
void publishMessage(const char* topic, String payload , boolean retained){
if (client.publish(topic, payload.c_str(), true))
Serial.println(“Message publised [”+String(topic)+"]: "+payload);
}
