Wiring
Check pinout, power supply, common GND and voltage levels before connecting the module.
Full code
#include <WiFi.h>
#include <PubSubClient.h>
WiFiClient espClient;
PubSubClient client(espClient);
void setup() {
WiFi.begin("YOUR_WIFI", "YOUR_PASSWORD");
while (WiFi.status() != WL_CONNECTED) delay(500);
client.setServer("broker.hivemq.com", 1883);
client.connect("esp32-client");
client.publish("engicalc/test", "hello");
}
void loop() {
client.loop();
}How it works
This lesson matches the page title and gives a clean starting point for this exact example.
Common mistakes
Check board selection, wiring, libraries, power supply and serial monitor baud rate.