Software design and Development Notes 2: serial port debugging tool based on QT design

   Serial communication is a problem we often encounter . Many times when we design a serial port application , We hope to have a simple 、 Visual way to verify it . In this article, we will base on QT Design a serial port debugging tool .

1、 summary

   Before starting software design , Let's briefly analyze the main contents of such a small software . We believe that the software needs the following aspects ：

• Configuration of serial port parameters , We hope that the serial port number can be automatically searched , We can select the corresponding configuration parameters .
• Input of sending data , For this software, we need to input the corresponding data to realize the sending of commands and messages , So we need to design the data input area and send interactive buttons .
• Display of received information , As a debugging tool , We certainly want to be able to see the message sent by the target device at a glance , So we need a display area to display the received area .
• Display of running status , We want to give feedback on the status of the operation to indicate whether the action of the operation is executed , So we need the status bar to implement this requirement .
• Other auxiliary functions , Also, send count 、 Receive count 、 Data storage and other functions are sometimes required , So let's consider it together .
     There are many serial port tools on the Internet , The reason why we want to implement such a serial port debugging tool by ourselves , There are two main reasons . One is , The corresponding tools found on the internet sometimes a single tool can not fully meet our needs , So we design this tool according to our own needs, which can better meet our needs of serial port debugging . Two is , Through the implementation of such a tool , We can deepen our understanding of serial communication .

2、 Interface design

   Based on the requirements analyzed in the previous section , Let's design the software interface first . We are QT Based on QMainWindow Class to generate an operation interface , Include menu bar 、 Toolbar and status bar to meet the requirements for status display and operation commands in the requirements .
   And in the middle display area , We divide it into 3 That's ok 2 Column . Set from top to bottom in the left column ： Serial port configuration operation area 、 Receive configuration area and send configuration area . Set from top to bottom in the right column ： Dynamic curve display area 、 Information receiving display area and information sending input area . The specific interface settings are shown in the following figure ：

   After completing the layout as shown in the figure above , We can choose to configure the parameters of the space in the properties , You can also add related parameters to the code , I am used to doing it in code . After finishing the whole layout, we try to run the program , In normal operation, the following interface appears ：

   The above figure is the running interface after the layout is completed , But we haven't implemented the corresponding coding yet , Therefore, the functions proposed in the first section cannot be realized at present .

3、 coded

   The next section , We will code and implement the corresponding functions in the future . We mainly divide the functions into parameter setting and operation functions 、 The function of data input and transmission and the function of data reception and display are realized .

3.1、 Parameter setting and operation function

   The parameter configuration can be used directly except for the serial port number ComboBox Control . Serial port number , We want to search the serial port installed on the computer and add it to the control . The specific implementation is as follows ：

// Search for available serial ports , And added to the serial port combo box 
void MainWindow::SearchSerialPorts()
{
    ui->comboBoxPort->clear();

    foreach(const QSerialPortInfo &info,QSerialPortInfo::availablePorts())
    {
        ui->comboBoxPort->addItem(info.portName());
    }
}

   After configuring the serial port parameters , We can open the serial port to establish a connection . It should be noted that when we open the remote connection between serial ports , We need to establish a signal slot connection between the data receiving of the serial port and our data receiving and processing function . The specific implementation is as follows ：

// Open the serial port 
void MainWindow::on_actionConnect_triggered()
{
    serialPort->setPortName(ui->comboBoxPort->currentText());

    if(serialPort->open(QIODevice::ReadWrite))              // Open serial port successfully 
    {
        serialPort->setBaudRate(ui->comboBoxBaud->currentText().toInt());       // set baud rate 

        switch(ui->comboBoxData->currentIndex())                   // Set the number of data bits 
        {
            case 1:serialPort->setDataBits(QSerialPort::Data8);break;
            default: break;
        }

        switch(ui->comboBoxParity->currentIndex())                   // Set parity 
        {
            case 0: serialPort->setParity(QSerialPort::NoParity);break;
            default: break;
        }

        switch(ui->comboBoxStop->currentIndex())                     // Set stop bit 
        {
            case 1: serialPort->setStopBits(QSerialPort::OneStop);break;
            case 2: serialPort->setStopBits(QSerialPort::TwoStop);break;
            default: break;
        }

        serialPort->setFlowControl(QSerialPort::NoFlowControl);     // set flow control 

        // Connection slot function 
        QObject::connect(serialPort, &QSerialPort::readyRead, this, &MainWindow::ReadSerialData);

        //  Set whether the control can be used 
        ui->actionConnect->setEnabled(false);
        ui->actionClose->setEnabled(true);
        ui->actionRefresh->setEnabled(false);
    }
    else    // Open failure prompt 
    {

        QMessageBox::information(this,tr(" error "),tr(" Failed to open serial port ！"),QMessageBox::Ok);
    }
}

   alike , In addition to opening the serial port to establish a connection , You also need to close the serial port and disconnect , The specific code is as follows ：

// Turn off the serial port 
void MainWindow::on_actionClose_triggered()
{
    serialPort->clear();
    serialPort->close();

    //  Set whether the control can be used 
    ui->actionConnect->setEnabled(true);
    ui->actionClose->setEnabled(false);
    ui->actionRefresh->setEnabled(true);
}

3.2、 Data input and transmission function

   Data input and transmission , We designed 5 Bar command , Each command can be sent manually through the following buttons , It can also be sent automatically . When automatic circular transmission , Each selected command will be polled and sent at a set time interval .
   First, let's take a look at the process of timing periodic transmission . We define a timer , Trigger the sending command with the time period we set , Send one command each time the check box is selected , Cycle in sequence until the cycle transmission is stopped manually . The specific code is as follows ：

// Timed periodic transmission 
void MainWindow::CycleSendData()
{
    QCheckBox* cbSend;

    while(true)
    {
        snIndex=snIndex>=6?1:snIndex;

        cbSend=ui->groupBoxMessage->findChild<QCheckBox*>(QString("checkBoxSendEnable%1").arg(QString::number(snIndex)));

        if(cbSend->isChecked())
        {
            WriteSerialData(snIndex);
            snIndex++;
            break;
        }

        snIndex++;
    }
}

   For manual single transmission, determine which button triggers the action, and then operate the corresponding data input box , Send the contents in the specified format . The specific operation code is as follows ：

// Button triggers sending 
void MainWindow::SingleSendData()
{
    //  Determine if the Sender yes QPushButton Is executed 
    if (QPushButton* btn = dynamic_cast<QPushButton*>(sender()))
    {
        QString senderName;
        int sn=0;

        senderName = btn->objectName();
        sn = senderName.replace("pushButtonSend", "").toInt();

        if((0<sn) && (sn<6))
        {
            WriteSerialData(sn);
        }
    }
}

3.3、 Data receiving and reality function

   In our design , Receiving data is relatively simple . When the serial port receives data, it will trigger our receiving data processing function , And will be displayed in the format we set , The specific implementation code is as follows ：

// Receive data from serial port 
void MainWindow::ReadSerialData()
{
    QByteArray rxDatas;
    QString context;

    rxDatas=serialPort->readAll();

    if(!rxDatas.isNull())
    {
        if(ui->checkBoxRecieve->isChecked())    // Hexadecimal display 
        {
             context = rxDatas.toHex(' ');
             context=context.toUpper();
        }
        else    //ASCII Show 
        {
            context = rxDatas;
        }

        QString timeStrLine="["+QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss")+"][ receive ]: ";
        context = timeStrLine+context+"\n\r";

        QString content = "<span style=\" color:blue;\">"+context+"</span>";
        ui->textBrowser->append(content);

        receivedBytes=receivedBytes+rxDatas.size();
        ui->lcdNumberRecieve->display(receivedBytes);

        ui->statusbar->showMessage(tr(" Successfully read %1 Bytes of data ").arg(rxDatas.size()));
    }

    rxDatas.clear();
}

4、 Summary

   After code debugging , Let's test the developed tool . First, we install a virtual serial port software to simulate the serial port we use for testing . If there is a hardware interface, it is best to , But there is no serial port on my computer , So we use virtual serial port to simulate a pair of serial ports . The specific configuration is shown in the figure below ：

   We use another serial port tool to realize communication verification with the tool we developed . We use access port To communicate with this tool .access port Use COM12,SerialMaster Use COM12, The corresponding serial port parameters are configured to be consistent . The specific configuration is shown in the figure below ：

   We use access port send data ,SerialMaster Received and displayed as blue characters in the display area . Again, we pass SerialMaster Send a message manually , Can be in access port See the corresponding data and in SerialMaster The display area of is displayed as red characters . As shown in the figure below ：

   Then we experimented with automatic cyclic transmission . We will send and get three command inputs , And select the corresponding check box as selected . And select the auto send checkbox , The corresponding command will be sent according to the set time interval . As shown in the figure below ：

   Here, the serial port debugging tool we want is basically implemented , Of course , In the future, we can also modify or add some functions to adapt to different applications , It can even be embedded in some applications to achieve the necessary testing functions . We publish the code to Gitee, Welcome to download and exchange .
Full code download address ：https://gitee.com/ErichMoonan/serial-master

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