Variable input from php form at other webserver

[rochmatsalim]

Hi Everyone...
I want to get some variable from other webserver, that will I use to input ESP32 RFID Write Code.

Can anyone send me an example code?

[rochmatsalim]

I get from Deeseek 👍
#include <WiFi.h>
#include <HTTPClient.h>
#include <SPI.h>
#include <MFRC522.h>

// Wi-Fi credentials
const char* ssid = "YOUR_WIFI_SSID";
const char* password = "YOUR_WIFI_PASSWORD";

// Web server URL
const char* serverUrl = "http://yourserver.com/getVariable"; // Replace with your server URL

// RFID pins
#define SS_PIN 5 // ESP32 pin GPIO5
#define RST_PIN 27 // ESP32 pin GPIO27

MFRC522 mfrc522(SS_PIN, RST_PIN); // Create MFRC522 instance

void setup() {
Serial.begin(115200);

// Connect to Wi-Fi
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.println("Connecting to Wi-Fi...");
}
Serial.println("Connected to Wi-Fi");

// Initialize SPI and MFRC522
SPI.begin();
mfrc522.PCD_Init();
Serial.println("RFID reader initialized");
}

void loop() {
if (WiFi.status() == WL_CONNECTED) {
// Fetch variable from web server
String variable = fetchVariableFromServer();
if (variable != "") {
Serial.println("Fetched variable: " + variable);

  // Write variable to RFID tag
  writeToRFID(variable);
}

} else {
Serial.println("Wi-Fi disconnected. Reconnecting...");
WiFi.begin(ssid, password);
}

delay(5000); // Wait before next iteration
}

String fetchVariableFromServer() {
HTTPClient http;
String payload = "";

// Send GET request to server
http.begin(serverUrl);
int httpCode = http.GET();

if (httpCode == HTTP_CODE_OK) {
payload = http.getString(); // Get the response payload
Serial.println("Server response: " + payload);
} else {
Serial.println("Error fetching variable from server. HTTP code: " + String(httpCode));
}

http.end();
return payload;
}

void writeToRFID(String data) {
// Prepare RFID tag for writing
if (!mfrc522.PICC_IsNewCardPresent() || !mfrc522.PICC_ReadCardSerial()) {
Serial.println("No RFID tag present.");
return;
}

// Write data to the RFID tag
byte buffer[18]; // MIFARE Classic blocks are 16 bytes, but we need 2 extra bytes for the trailer
data.getBytes(buffer, 18);

MFRC522::MIFARE_Key key;
for (byte i = 0; i < 6; i++) key.keyByte[i] = 0xFF; // Default key

// Authenticate and write to block 4 (you can change this)
if (mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, 4, &key, &(mfrc522.uid)) == MFRC522::STATUS_OK) {
if (mfrc522.MIFARE_Write(4, buffer, 16) == MFRC522::STATUS_OK) {
Serial.println("Data written to RFID tag successfully.");
} else {
Serial.println("Error writing to RFID tag.");
}
} else {
Serial.println("Authentication failed.");
}

mfrc522.PICC_HaltA(); // Halt PICC
mfrc522.PCD_StopCrypto1(); // Stop encryption on PCD
}