DHT11 Temperature & Humidity Web Server

The DHT11 is a small, slow, cheap sensor that reports temperature (°C) and relative humidity (%) over one data wire. Read it every couple of seconds — no faster.

To refresh without reloading, the browser polls (like Project 8): two timers fetch /temperature and /humidity every 10 s and drop the numbers into the page:

setInterval(function () {
  xhttp.open("GET", "/temperature", true);   // fetch just the number
  ...
}, 10000);                                     // every 10 seconds

• DHT sensor library (Adafruit)
• Adafruit Unified Sensor (dependency)
• ESPAsyncWebServer
• AsyncTCP (ESP32)

The first two are in the Library Manager; the async pair install as ZIPs (as in Projects 7–8).

Set your Wi‑Fi credentials, upload, open Serial Monitor at 115200, press EN/RESET:

==============================================
 Project 9: ESP32 DHT11 Web Server
==============================================
DHT11 data -> GPIO 4
Connecting to Wi-Fi: MyNetwork
....
Wi-Fi connected!
Open this address in your browser:  http://192.168.1.42
----------------------------------------------
[DHT] Temperature: 21.4 C
[DHT] Humidity: 63.9 %

The improved logging prints labeled readings with units (the original printed a bare number), so you can confirm the sensor works before opening the page.