read_from_sd.cpp

  //access SD card for WiFi SSID and Password
  if (!SD_MMC.begin()) {
    Serial.println("Failed to mount card");
    return;
  }

  File file = SD_MMC.open("/ssid.txt", FILE_READ);
  File file_pwd = SD_MMC.open("/pwd.txt", FILE_READ);
  
  if (!file || !file_pwd) {
    Serial.println("Opening file to read failed");
    return;
  }
 
  Serial.println("File Content: SSID");
  while (file.available()) {
    int l = file.readBytesUntil('\n', ssid, sizeof(ssid));
    if (l > 0 && ssid[l-1] == '\r') {
      l--;
    }
  ssid[l] = 0;
  }
  Serial.println(ssid);

  Serial.println("File Content: Password");
  while (file_pwd.available()) {
    int l = file_pwd.readBytesUntil('\n', password, sizeof(password));
    if (l > 0 && password[l-1] == '\r') {
      l--;
    }
  password[l] = 0;
  }
  Serial.println(password);
  
  file.close();
  file_pwd.close();