代码如下：
QextSerialPort *port = new QextSerialPort("/dev/ttyS0", QextSerialPort::Polling);
bool on = port->open(QIODevice::ReadWrite);
qDebug() << on;
port->setBaudRate(BAUD9600);
port->setFlowControl(FLOW_OFF);
port->setParity(PAR_NONE);
port->setDataBits(DATA_8);
port->setStopBits(STOP_1);
//set timeouts to 500 ms
port->setTimeout(500);
串口一直打不开，on=false
