原文：https://blog.csdn.net/uyy203/article/details/51048292

      
while(Serial.available()>0)
       WifiSerial.write(Serial.read());


      while(WifiSerial.available()>0)
       Serial.write(WifiSerial.read());

............

      while (1)
      {
        if (WifiSerial.available()>0)
        {
          char c = WifiSerial.read();
          data += c;
        }
        if (data.indexOf("done")!=-1)
        {
          break;
        }
      }