Nell’articolo di oggi vedremo come utilizzare realizzare una web app (o server web totalmente autonomo) con ESP32. Il progetto in questione controllerà due pin GPIO ai quali sono collegati a due LED. Utilizzeremo Arduino IDE. Potremmo accedere con qualsiasi device su rete locale.
Lista componenti
- ESP32-WROVER
- Breadboard
- 2x led
- 3x jumper
- GPIO extension board (falcolatitivo)
Fasi salienti del progetto
Il server gestirà due pin GPIO.
Sarà possibile accedere al server WEB digitando l’indirizzo IP dell’ESP32 su broswer (rete locale).
Cliccando i bottoni che compariranno sul web server si può cambiare lo stato del LED da accesso a spento e viceversa.
Collegamenti
In seguito schema e diagramma di collegamento. Per costruire un circuito ricordati di tenere la scheda spenta.
Codice
Se questo è il tuo primo articolo ti invito di leggere prima questo per l’installazione dei driver della scheda. Ecco qui un piccolo riepilogo prima di compilare e caricare il codice.
Ecco qui lo sketch:
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// Load Wi-Fi library #include <WiFi.h> // Replace with your network credentials const char* ssid = "REPLACE_WITH_YOUR_SSID"; const char* password = "REPLACE_WITH_YOUR_PASSWORD"; // Set web server port number to 80 WiFiServer server(80); // Variable to store the HTTP request String header; // Auxiliar variables to store the current output state String output26State = "off"; String output27State = "off"; // Assign output variables to GPIO pins const int output26 = 26; const int output27 = 27; // Current time unsigned long currentTime = millis(); // Previous time unsigned long previousTime = 0; // Define timeout time in milliseconds (example: 2000ms = 2s) const long timeoutTime = 2000; void setup() { Serial.begin(115200); // Initialize the output variables as outputs pinMode(output26, OUTPUT); pinMode(output27, OUTPUT); // Set outputs to LOW digitalWrite(output26, LOW); digitalWrite(output27, LOW); // Connect to Wi-Fi network with SSID and password Serial.print("Connecting to "); Serial.println(ssid); WiFi.begin(ssid, password); while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); } // Print local IP address and start web server Serial.println(""); Serial.println("WiFi connected."); Serial.println("IP address: "); Serial.println(WiFi.localIP()); server.begin(); } void loop(){ WiFiClient client = server.available(); // Listen for incoming clients if (client) { // If a new client connects, currentTime = millis(); previousTime = currentTime; Serial.println("New Client."); // print a message out in the serial port String currentLine = ""; // make a String to hold incoming data from the client while (client.connected() && currentTime - previousTime <= timeoutTime) { // loop while the client's connected currentTime = millis(); if (client.available()) { // if there's bytes to read from the client, char c = client.read(); // read a byte, then Serial.write(c); // print it out the serial monitor header += c; if (c == '\n') { // if the byte is a newline character // if the current line is blank, you got two newline characters in a row. // that's the end of the client HTTP request, so send a response: if (currentLine.length() == 0) { // HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK) // and a content-type so the client knows what's coming, then a blank line: client.println("HTTP/1.1 200 OK"); client.println("Content-type:text/html"); client.println("Connection: close"); client.println(); // turns the GPIOs on and off if (header.indexOf("GET /26/on") >= 0) { Serial.println("GPIO 26 on"); output26State = "on"; digitalWrite(output26, HIGH); } else if (header.indexOf("GET /26/off") >= 0) { Serial.println("GPIO 26 off"); output26State = "off"; digitalWrite(output26, LOW); } else if (header.indexOf("GET /27/on") >= 0) { Serial.println("GPIO 27 on"); output27State = "on"; digitalWrite(output27, HIGH); } else if (header.indexOf("GET /27/off") >= 0) { Serial.println("GPIO 27 off"); output27State = "off"; digitalWrite(output27, LOW); } // Display the HTML web page client.println("<!DOCTYPE html><html>"); client.println("<head><meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">"); client.println("<link rel=\"icon\" href=\"data:,\">"); // CSS to style the on/off buttons // Feel free to change the background-color and font-size attributes to fit your preferences client.println("<style>html { font-family: Helvetica; display: inline-block; margin: 0px auto; text-align: center;}"); client.println(".button { background-color: #4CAF50; border: none; color: white; padding: 16px 40px;"); client.println("text-decoration: none; font-size: 30px; margin: 2px; cursor: pointer;}"); client.println(".button2 {background-color: #555555;}</style></head>"); // Web Page Heading client.println("<body><h1>ESP32 Web Server</h1>"); // Display current state, and ON/OFF buttons for GPIO 26 client.println("<p>GPIO 26 - State " + output26State + "</p>"); // If the output26State is off, it displays the ON button if (output26State=="off") { client.println("<p><a href=\"/26/on\"><button class=\"button\">ON</button></a></p>"); } else { client.println("<p><a href=\"/26/off\"><button class=\"button button2\">OFF</button></a></p>"); } // Display current state, and ON/OFF buttons for GPIO 27 client.println("<p>GPIO 27 - State " + output27State + "</p>"); // If the output27State is off, it displays the ON button if (output27State=="off") { client.println("<p><a href=\"/27/on\"><button class=\"button\">ON</button></a></p>"); } else { client.println("<p><a href=\"/27/off\"><button class=\"button button2\">OFF</button></a></p>"); } client.println("</body></html>"); // The HTTP response ends with another blank line client.println(); // Break out of the while loop break; } else { // if you got a newline, then clear currentLine currentLine = ""; } } else if (c != '\r') { // if you got anything else but a carriage return character, currentLine += c; // add it to the end of the currentLine } } } // Clear the header variable header = ""; // Close the connection client.stop(); Serial.println("Client disconnected."); Serial.println(""); } } |
Compila e carica il codice sull’ESP32, ed ecco qui che potremo visualizzare l’indirizzo IP che utilizzeremo per accedere via broswer dal monitor seriale.
Accesso server web
Per accedere al server web, apri il browser, incolla l’indirizzo IP di ESP32 e vedrai la pagina seguente.
Ora puoi verificare se il tuo server web funziona correttamente. Fare clic sui pulsanti per controllare l’accensione e spegmineto di LED.
Al prossimo articolo. Grazie per la lettura.
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Link utili
- Arduino UNO R3
- Elegoo UNO R3
- Arduino Starter Kit per principianti
- Elegoo Advanced Starter Kit
- Arduino Nano