توصيل عقدة المستشعر وبرمجتها

Now you turn the plan into hardware. You will wire the DHT22 to the ESP32 and write code that reads climate data and publishes it. 🔌

Connect the DHT22's VCC to 3.3V and GND to ground on the ESP32. Shared ground is what lets the two parts agree on signals.

Run the sensor's data line to a GPIO pin and add a pull-up resistor so the idle line stays clean and reads reliably.

At the top of the sketch, pull in the tools you need: the DHT library for the sensor and PubSubClient for MQTT.

Tell the library which pin and sensor type you used by creating a DHT object. This becomes your handle for every reading.

In setup() you open Serial, start the sensor with dht.begin(), and connect to WiFi so the node is ready before the loop runs.

Each cycle, call readTemperature() and readHumidity() to grab fresh numbers from the room into two variables.

Sensors sometimes return NaN. Check isnan() and skip publishing that round so you never send junk to the cloud.

Point PubSubClient at your broker's address and port, then keep a reconnect helper so a dropped link is rejoined automatically.

Send each value to its topic with client.publish(). The cloud now receives a fresh temperature every cycle.

Don't flood the network. Use millis() timing to publish about once every few seconds, which is plenty for room climate.

Test your sensor-node code.

You wired the DHT22, read clean values, guarded bad reads, and published them over MQTT. Your sensor node is alive and talking. 📡