take over some code from mainwindow

DownloadDCFirmware/update.h

@@ -21,6 +21,7 @@
 #define SERIAL_PORT "ttyUSB0"
 #endif
 
+class QSerialPort;
 class Update : public QObject {
     Q_OBJECT
 
@@ -46,6 +47,12 @@ class Update : public QObject {
         return QStringLiteral("+%1s").arg(secs, 7, 'f', 2, QChar('0'));
     }
 
+
+    bool openSerialPort();
+    bool closeSerialPort();
+
+    QSerialPort *m_serial;
+
 public:
     enum class DownloadResult {OK, ERROR, TIMEOUT, NOP};
     enum class FileTypeJson {CONFIG=1, DEVICE=2, CASH=3, SERIAL=4, TIME=5, PRINTER=6};