serial port programming in qt

[high_flyer]

Why are you commenting out these lines? with out them you don't have an initialized serial port objet.
Also, QextSerialPort is made crossplatform, so you don't need to explicitly use Posix_QextSerialPort (this wont compile under windows) - there are defines in the code that will select the correct version for you.
Just use QextSerialPort.

[sar_van81]

high_flyer:

if i use QextSerialPort instead of Posix_QextSerialPort, it shows me the following error:

home/qtprograms/qwt/qextserial/qextserialport-0.8.0/win_qextserialport.h:11:21: error: windows.h: No such file or directory
/home/qtprograms/qwt/qextserial/qextserialport-0.8.0/win_qextserialport.h:57:7: warning: no newline at end of file
In file included from tux.cpp:21:
/home/qtprograms/qwt/qextserial/qextserialport-0.8.0/qextserialport.h:26:7: warning: no newline at end of file
/home/qtprograms/qwt/qextserial/qextserialport-0.8.0/win_qextserialport.h:50: error: ‘HANDLE’ does not name a type
/home/qtprograms/qwt/qextserial/qextserialport-0.8.0/win_qextserialport.h:51: error: ‘COMMCONFIG’ does not name a type
/home/qtprograms/qwt/qextserial/qextserialport-0.8.0/win_qextserialport.h:52: error: ‘COMMTIMEOUTS’ does not name a type
make: *** [tux.o] Error 1
.
So only i used Posix_QextSerialPort. Should i define somewhere about _TTY_POSIX ? Also as i said before when i include them in my code its prompting me segmentation fault.

[high_flyer]

So only i used Posix_QextSerialPort. Should i define somewhere about _TTY_POSIX ?

Exactly - You should add DEFINES += _TTY_POSIX in your pro file (or if you are using KDevelop it has a field for that in the qmake configuration).

[sar_van81]

high_flyer:

that parameter has already been set when i untar the qextserial package. should i specify that in my application pro file ?

Let me explain what i have done so far :

1). Downloaded the qextserial package , untarred and entered qmake ,make. there were the following libraries created:
libqextserialport.so libqextserialport.so.1 libqextserialport.so.1.0 libqextserialport.so.1.0.0

2). Then created a directory ,copied my source files. entered the header files and the libraries for qextserial in my project file. then entered make.

is this procedure correct ? else can you say me the correct one ?

[high_flyer]

should i specify that in my application pro file ?

yes.

is this procedure correct ? else can you say me the correct one ?

It should work.
But I would not copy the header files and libs, I would link to them or user the -L and -I in my make file.
But that is a subjective private taste matter, your way should work just as well.

[sar_van81]

hi ,

i specified in my project file also and it compiled successfully.but still the same error comes . Is there any permission i need to set to serial port ? i'l post my full code here if any one find any error please point me :

#include <qwidget.h>
#include <qapplication.h>
#include <stdlib.h>
 
#include <qextserialport.h>
 
class Widget : public QWidget
{
public:
    Widget( QWidget *parent=0, const char *name=0 );
private:
    int mouse;
    int mouseidx;
};
 
Widget::Widget( QWidget *parent, const char *name )
    : QWidget( parent, name)
{
    setMinimumSize(640,480 );
 
	QextSerialPort *note= new QextSerialPort("/dev/ttyS0");
	note->setBaudRate(BAUD115200);
	note->setParity(PAR_NONE);
	note->setDataBits(DATA_8);
	note->setStopBits(STOP_1);
	note->open(IO_ReadOnly);	
}
 
int main( int argc, char **argv )
{
    QApplication a( argc, argv );
    Widget connect1;
    a.setMainWidget( &connect1 );
    connect1.show();
    return a.exec();
}

#include <qwidget.h>
#include <qapplication.h>
#include <stdlib.h>

#include <qextserialport.h>

class Widget : public QWidget
{
public:
    Widget( QWidget *parent=0, const char *name=0 );
private:
    int mouse;
    int mouseidx;
};

Widget::Widget( QWidget *parent, const char *name )
    : QWidget( parent, name)
{
    setMinimumSize(640,480 );

	QextSerialPort *note= new QextSerialPort("/dev/ttyS0");
	note->setBaudRate(BAUD115200);
	note->setParity(PAR_NONE);
	note->setDataBits(DATA_8);
	note->setStopBits(STOP_1);
	note->open(IO_ReadOnly);	
}

int main( int argc, char **argv )
{
    QApplication a( argc, argv );
    Widget connect1;
    a.setMainWidget( &connect1 );
    connect1.show();
    return a.exec();
}

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[high_flyer]

compiled successfully.but still the same error comes .

I guess you mean the segmentation fault.

Your code has the following problems:

QextSerialPort *note= new QextSerialPort("/dev/ttyS0");

QextSerialPort *note= new QextSerialPort("/dev/ttyS0");

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You are allocating the serial port on to a local pointer.
You will not be able to access the serial port outside the constructor.
'note' needs to be a member variable.

Where is the code that handels the reading/writing to the serial port?

[sar_van81]

theLSB:
I did not add the read/write operation. i thougth first let me open the port sucessfuly. then,read that.

'note' needs to be a member variable

Do you mean that i need to declare it under protected and use it in the constructor ?

[high_flyer]

Do you mean that i need to declare it under protected and use it in the constructor ?

No, you need to declare it as a member variable.
Do you know what a member variable is?

class Widget : public QWidget
{
 private: //depends on your needs, this can be any access mode
  QextSerialPort *m_note;
public:
    Widget( QWidget *parent=0, const char *name=0 );
private:
    int mouse;
    int mouseidx;
};
 
Widget::Widget( QWidget *parent, const char *name )
    : QWidget( parent, name),
m_note(NULL)
{
    setMinimumSize(640,480 );
 
    m_note= new QextSerialPort("/dev/ttyS0");
   if(note)
   {
    m_note->setBaudRate(BAUD115200);
    m_note->setParity(PAR_NONE);
    m_note->setDataBits(DATA_8);
    m_note->setStopBits(STOP_1);
    m_note->open(IO_ReadOnly);   
   }
}

class Widget : public QWidget
{
 private: //depends on your needs, this can be any access mode
  QextSerialPort *m_note;
public:
    Widget( QWidget *parent=0, const char *name=0 );
private:
    int mouse;
    int mouseidx;
};
 
Widget::Widget( QWidget *parent, const char *name )
    : QWidget( parent, name),
m_note(NULL)
{
    setMinimumSize(640,480 );
 
    m_note= new QextSerialPort("/dev/ttyS0");
   if(note)
   {
    m_note->setBaudRate(BAUD115200);
    m_note->setParity(PAR_NONE);
    m_note->setDataBits(DATA_8);
    m_note->setStopBits(STOP_1);
    m_note->open(IO_ReadOnly);   
   }
}

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[sar_van81]

high_flyer:

yeah i did as you said. i tried both the ways-private or protected. But no use.

[high_flyer]

But no use.

Could you be a bit more descriptive?
The access mode has nothing to do with it.

[sar_van81]

first i tried declaring the Qextserialport as a private member variable, compiled and when i rum the same error came. next i tried declaring it as protected member variable, the same thing happened.