Regarding Projector Programming using QT
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Yes. @Pablo-J-Rogina . I am connecting the projector to Quectel QCOM application. Now I want to skip that application and create my customised application to control the projector.
I wrote a programme based on the guidelines of Quectel to switch off the projector. Following is the code. Even I used the QSerialPort code. But the projector couldn't switch off. However using the command prompt of the Quectel QCOM application, I could control the projector.
main.cpp
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDebug>
#include<QSerialPort>
#include<string>
#include<QtGui>
#include <QMessageBox>using namespace std;
QSerialPort *serial;
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
}MainWindow::~MainWindow()
{
delete ui;
}void MainWindow::on_pushButton_clicked()
{
QMessageBox::information(this,"Title here","Hello World");
serial = new QSerialPort(this);
serial->setPortName("COM3");
serial->setBaudRate(QSerialPort::Baud115200,QSerialPort::AllDirections);
serial->setDataBits(QSerialPort::Data8);
serial->setFlowControl(QSerialPort::NoFlowControl);
serial->setStopBits(QSerialPort::OneStop);
serial->setParity(QSerialPort::NoParity);if(!serial->open(QIODevice::ReadWrite)) { qDebug()<<"error: can't open com port"; } QString command = "WT+LEDE=0\n"; QByteArray x = command.toLocal8Bit(); serial->write(x);}
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{
Q_OBJECTpublic:
MainWindow(QWidget *parent = nullptr);
~MainWindow();private slots:
void on_pushButton_clicked();private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H#-------------------------------------------------
Project created by QtCreator 2019-11-02T10:55:21
#-------------------------------------------------
QT += core gui serialport
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = GUISerialPort
TEMPLATE = appSOURCES += main.cpp
mainwindow.cppHEADERS += mainwindow.h
FORMS += mainwindow.ui
@Prath said in Regarding Projector Programming using QT:
if(!serial->open(QIODevice::ReadWrite))
Does open() succeed?
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@Prath said in Regarding Projector Programming using QT:
if(!serial->open(QIODevice::ReadWrite))
Does open() succeed?
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@jsulm Yes. Open succeeded. But still, the projector could not read the commands which I am sending through serial port.
@Prath You should check what write() returns and connect a slot to https://doc.qt.io/qt-5/qserialport.html#errorOccurred to see whether you get any errors.
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@Prath You should check what write() returns and connect a slot to https://doc.qt.io/qt-5/qserialport.html#errorOccurred to see whether you get any errors.
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@jsulm Could you please help me with the syntax for checking the error. I am completely new in using this.
@Prath You know how to connect a slot to a signal?
https://doc.qt.io/qt-5/signalsandslots.html -
Yeah @jsulm . We have to connect this signal [signal]void QSerialPort::errorOccurred(QSerialPort::SerialPortError error) to the slot right?
Is this correct?
void MainWindow::errorReport(QSerialPort::SerialPortError error)
{
if(error!=0)
qDebug()<<"ERROR:"<<endl<<error; // nothing printed
}connect(this->Serial,SIGNAL(error(QSerialPort::SerialPortError)),this,SLOT(errorReport(QSerialPort::SerialPortError)));
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Yeah @jsulm . We have to connect this signal [signal]void QSerialPort::errorOccurred(QSerialPort::SerialPortError error) to the slot right?
Is this correct?
void MainWindow::errorReport(QSerialPort::SerialPortError error)
{
if(error!=0)
qDebug()<<"ERROR:"<<endl<<error; // nothing printed
}connect(this->Serial,SIGNAL(error(QSerialPort::SerialPortError)),this,SLOT(errorReport(QSerialPort::SerialPortError)));
@Prath said in Regarding Projector Programming using QT:
Is this correct?
Signal is https://doc.qt.io/qt-5/qserialport.html#errorOccurred not error. Just check the documentation.
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I think it is correct @jsulm. We are catching the signal using the slot and then displaying the signal.
@Prath
You wroteconnect(this->Serial,SIGNAL(error(QSerialPort::SerialPortError)),this,SLOT(errorReport(QSerialPort::SerialPortError)));Where you have
SIGNAL(error(QSerialPort::SerialPortError))@jsulm is expectingSIGNAL(errorOccurred(QSerialPort::SerialPortError)). If what you have works, we do not understand how.If you are writing new code and would change over to the new signal/slot syntax you would presumably receive a compile-time error.
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Your MainWindow class does not have such a signal, it's one from the QSerialPort.
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When I click on the push button the function on_pushButton_clicked is called and then I call the Qserialport to check the error. I think the code is written correctly.
What's your take?
@Prath said in Regarding Projector Programming using QT:
What's your take?
Your connect is wrong: MainWindow does NOT have signal error(QSerialPort::QSerialPort), this signal is in QSerialPort, so not in "this" but in "serial".
And please do not post screen-shots, copy paste your code...
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@Prath said in Regarding Projector Programming using QT:
What's your take?
Your connect is wrong: MainWindow does NOT have signal error(QSerialPort::QSerialPort), this signal is in QSerialPort, so not in "this" but in "serial".
And please do not post screen-shots, copy paste your code...
this signal is in QSerialPort, so not in "this" but in "serial".
Is this a case where changing to new-style signal/slot syntax would generate an error for the wrong "context" variable? Or, would testing the return result from the
connect()or from https://doc.qt.io/qt-5/qmetaobject-connection.html#operator-bool in code tell the user if the connection has failed because of the wrong context? -
this signal is in QSerialPort, so not in "this" but in "serial".
Is this a case where changing to new-style signal/slot syntax would generate an error for the wrong "context" variable? Or, would testing the return result from the
connect()or from https://doc.qt.io/qt-5/qmetaobject-connection.html#operator-bool in code tell the user if the connection has failed because of the wrong context? -
If you mean use several QSerialPorts at the same time in one application then yes, no problem with that. If you mean something else, please give more details.
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If you mean use several QSerialPorts at the same time in one application then yes, no problem with that. If you mean something else, please give more details.
