serveur-web.ino
The sketch that turns the NodeMCU into an IoT gadget: a locally served HTML page, links driving the LED, remote reboot. No infrastructure — it all fits in the 4 MB of flash.
Hardware required
An ESP-12E module (ESP8266EX, 2.4 GHz Wi-Fi) mounted on a NodeMCU / Wemos D1 mini board, powered over micro-USB. A 2.4 GHz Wi-Fi access point (the 8266 cannot see 5 GHz).
Wiring
No mandatory wiring; LED on D4. Micro-USB power suffices (Wi-Fi draws ~200 mA peaks).
How it works
ESP8266WebServer registers lambda routes; handleClient() serves requests at loop() pace. ESP.restart() reboots cleanly, handy when the module trips its watchdog. In the Arduino IDE, install the « esp8266 » package, select « NodeMCU 1.0 (ESP-12E Module) » then Upload (hold GPIO0 LOW if flashing fails). The A0 ADC reads 0-1 V (NodeMCU divider: 0-3.3 V).
Going further
Add the previous sketch's DHT11 to the page, or switch to access-point mode for router-free use.
serveur-web.ino
// Serveur web ESP8266 : page de controle LED D4 + bouton reboot.
#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>
const char *SSID = "votre-wifi";
const char *CLE = "votre-cle";
const int LED = 2;
ESP8266WebServer serveur(80);
void page() {
String h = "<h1>ESP8266</h1>"
"<p>LED : " + String(digitalRead(LED) == LOW ? "ALLUMEE" : "eteinte") + "</p>"
"<p><a href=/on>ALLUMER</a> | <a href=/off>ETEINDRE</a> | "
"<a href=/reboot>reboot</a></p>";
serveur.send(200, "text/html", h);
}
void setup() {
pinMode(LED, OUTPUT); digitalWrite(LED, HIGH); // LED eteinte (actif-bas)
Serial.begin(115200);
WiFi.mode(WIFI_STA);
WiFi.begin(SSID, CLE);
while (WiFi.status() != WL_CONNECTED) { delay(300); Serial.print("."); }
Serial.printf("\nhttp://%s/\n", WiFi.localIP().toString().c_str());
serveur.on("/", page);
serveur.on("/on", []() { digitalWrite(LED, LOW); page(); });
serveur.on("/off", []() { digitalWrite(LED, HIGH); page(); });
serveur.on("/reboot", []() { serveur.send(200, "text/plain", "bye");
ESP.restart(); });
serveur.begin();
}
void loop() { serveur.handleClient(); }