After using the open method to open the serial port and set the attributes, you can use Qt's class QSocketNotifier to monitor whether the serial port has data readability. Each qsocketnotify object listens to an event. When using QSocketNotifier to handle the serial port, you only need to set it to the Read attribute. QSocketNotifier sets three types of events: read, write and exception, as shown in the following table. Let's discuss how to implement a general event driven serial communication program combined with the QSocketNotifier module in Qt. This provides another solution for Qt serial communication under Linux. At Qt4 0 and above, a new module called QSocketNotifier is added, which is used to listen to the operation of system files, convert the operation into Qt event, enter the message loop queue of the system, and call the preset event acceptance function to process the event.

In fact, in the official documents of Qt, it is not recommended to use threads for processing, so a variety of alternative schemes are given, one of which is to use QSocketNotifier. When no data is received, the CPU can do other things, so it has high efficiency and is very convenient to use.

As long as the serial port receives data, it will notify the CPU to perform relevant operations in the form of events. Therefore, it is necessary to repeatedly read a large amount of data in the serial port. Generally, it is necessary to put a new thread into the serial port to check whether it consumes a lot of CPU resources. However, no matter which method is adopted, the data reception of serial port can only be realized by polling in Linux system, while the so-called event method with high efficiency can be used in Windows system. Now, in the versions based on Qt5 or above, the serial port module (such as QSerialPort) is integrated, or the serial port module control (such as qextserialport) developed by a third party is used. When programming in QT, serial port (UART) communication is often used. In the UI design of embedded Linux system, Qt library is commonly used.

Qt serial port read