2_FOTA.ino

void connect_wifi() {
  Serial.println("Waiting for WiFi");
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}


void firmwareUpdate(void) {
  WiFiClientSecure client;
  client.setCACert(rootCACertificate);
  httpUpdate.setLedPin(LED_BUILTIN, LOW);
  t_httpUpdate_return ret = httpUpdate.update(client, URL_fw_Bin);

  switch (ret) {
  case HTTP_UPDATE_FAILED:
    Serial.printf("HTTP_UPDATE_FAILD Error (%d): %s\n", httpUpdate.getLastError(), httpUpdate.getLastErrorString().c_str());
    break;

  case HTTP_UPDATE_NO_UPDATES:
    Serial.println("HTTP_UPDATE_NO_UPDATES");
    break;

  case HTTP_UPDATE_OK:
    Serial.println("HTTP_UPDATE_OK");
    break;
  }
}
int FirmwareVersionCheck(void) {
  String payload;
  int httpCode;
  String fwurl = "";
  fwurl += URL_fw_Version;
  fwurl += "?";
  fwurl += String(rand());
  Serial.println(fwurl);
  WiFiClientSecure * client = new WiFiClientSecure;

  if (client) 
  {
    client -> setCACert(rootCACertificate);

    // Add a scoping block for HTTPClient https to make sure it is destroyed before WiFiClientSecure *client is 
    HTTPClient https;

    if (https.begin( * client, fwurl)) 
    { // HTTPS      
      Serial.print("[HTTPS] GET...\n");
      // start connection and send HTTP header
      delay(100);
      httpCode = https.GET();
      delay(100);
      if (httpCode == HTTP_CODE_OK) // if version received
      {
        payload = https.getString(); // save received version
      } else {
        Serial.print("error in downloading version file:");
        Serial.println(httpCode);
      }
      https.end();
    }
    delete client;
  }
      
  if (httpCode == HTTP_CODE_OK) // if version received
  {
    payload.trim();
    if (payload.equals(FirmwareVer)) {
      Serial.printf("\nDevice already on latest firmware version:%s\n", FirmwareVer);
      return 0;
    } 
    else 
    {
      Serial.println(payload);
      Serial.println("New firmware detected");
      return 1;
    }
  } 
  return 0;  
}