Serial.write 在 Qt (C++) 中使程序崩溃

Question

我正在尝试向串行端口写入一个命令，这将改变我的电视输入，但是当我尝试向该端口写入必要的命令时，我得到了一个非常奇怪的输出。

#include <QCoreApplication>
#include <QSerialPort>
#include <Windows.h>

int set_id = 0;
int fd = -1;
int main(int argc, char *argv[])
{
    QCoreApplication app{argc, argv};

int timeInSeconds=0;
while(timeInSeconds>0)
{
    printf("%d...\n",timeInSeconds);
    Sleep(1000);
    timeInSeconds--;
}


QSerialPort serial;
serial.setBaudRate(QSerialPort::Baud9600);
serial.setDataBits(QSerialPort::Data8);
serial.setParity(QSerialPort::NoParity);
serial.setStopBits(QSerialPort::OneStop);
serial.setFlowControl(QSerialPort::NoFlowControl);
serial.setPortName("com3");

serial.open(QIODevice::ReadWrite);

/*char cmd1='x';
char cmd2='b';
int value=20;
char cmd[20];
int len;
if (value >= 0x100)
    len = sprintf(cmd, "%c%c %02x %02x %02x\r", cmd1, cmd2, set_id, value>>8, value&255);
else
{
    len = sprintf(cmd, "%c%c %02x %02x\r", cmd1, cmd2, set_id, value);
}

serial.write(cmd, len);
*/

char cmdHex[5]="0xc5";
serial.write(cmdHex);
serial.close();

int stall;
scanf("%d",&stall);

//return a.exec();
}

该代码应该将电视输入更改为 av。（从HDMI 1开始）另外，注释掉的块是我第一次尝试发送命令。

Answer 1

您应该学习 Qt 附带的 QSerialPort 示例。有 terminal 项目，它是交互式的（非常适合测试端口），cwritersync 做你想做的事。

这是完整的 cwritersync 代码：

/****************************************************************************
**
** Copyright (C) 2013 Laszlo Papp <lpapp@kde.org>
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QtSerialPort module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** As a special exception, The Qt Company gives you certain additional
** rights. These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include <QtSerialPort/QSerialPort>

#include <QTextStream>
#include <QCoreApplication>
#include <QFile>
#include <QStringList>

QT_USE_NAMESPACE

int main(int argc, char *argv[])
{
    QCoreApplication coreApplication(argc, argv);
    int argumentCount = QCoreApplication::arguments().size();
    QStringList argumentList = QCoreApplication::arguments();

    QTextStream standardOutput(stdout);

    if (argumentCount == 1) {
        standardOutput << QObject::tr("Usage: %1 <serialportname> [baudrate]").arg(argumentList.first()) << endl;
        return 1;
    }

    QSerialPort serialPort;
    QString serialPortName = argumentList.at(1);
    serialPort.setPortName(serialPortName);

    int serialPortBaudRate = (argumentCount > 2) ? argumentList.at(2).toInt() : QSerialPort::Baud9600;
    serialPort.setBaudRate(serialPortBaudRate);

    if (!serialPort.open(QIODevice::WriteOnly)) {
        standardOutput << QObject::tr("Failed to open port %1, error: %2").arg(serialPortName).arg(serialPort.errorString()) << endl;
        return 1;
    }

    QFile dataFile;
    if (!dataFile.open(stdin, QIODevice::ReadOnly)) {
        standardOutput << QObject::tr("Failed to open stdin for reading") << endl;
        return 1;
    }

    QByteArray writeData(dataFile.readAll());
    dataFile.close();

    if (writeData.isEmpty()) {
        standardOutput << QObject::tr("Either no data was currently available on the standard input for reading, or an error occurred for port %1, error: %2").arg(serialPortName).arg(serialPort.errorString()) << endl;
        return 1;
    }

    qint64 bytesWritten = serialPort.write(writeData);

    if (bytesWritten == -1) {
        standardOutput << QObject::tr("Failed to write the data to port %1, error: %2").arg(serialPortName).arg(serialPort.errorString()) << endl;
        return 1;
    } else if (bytesWritten != writeData.size()) {
        standardOutput << QObject::tr("Failed to write all the data to port %1, error: %2").arg(serialPortName).arg(serialPort.errorString()) << endl;
        return 1;
    } else if (!serialPort.waitForBytesWritten(5000)) {
        standardOutput << QObject::tr("Operation timed out or an error occurred for port %1, error: %2").arg(serialPortName).arg(serialPort.errorString()) << endl;
        return 1;
    }

    standardOutput << QObject::tr("Data successfully sent to port %1").arg(serialPortName) << endl;

    return 0;
}

Serial.write 在 Qt (C++) 中使程序崩溃

Serial.write crashes program in Qt (C++)

c++

serialization

qt

serial-port