cannot convert (void MainWindow::*) to void(*)() for argument '3' to int wiringPiISR(int,int,void(*)())

[gauravsharma0190]

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <wiringPi.h>
#include<QLabel>
#include <QDesktopWidget>
#include <QPixmap>
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QTimer>
#include <QTime>
#include <QTextEdit>
#include <QMessageBox>
#include <stdio.h>
#include <fcntl.h>
#include <getopt.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <wiringPi.h>
void myInterrupt();
#define BUTTON_PIN 0
volatile int eventCounter = 0;
// -------------------------------------------------------------------------
// myInterrupt:  called every time an event occurs


MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
       setenv("WIRINGPI_GPIOMEM", "1", 1);
    ui->setupUi(this);
    wiringPiSetup () ;
    pinMode (0, OUTPUT) ;
}

MainWindow::~MainWindow()
{
    delete ui;
}





void MainWindow::on_pushButton_clicked()
{
    ui->flow2->setText("Hello");


if(wiringPiISR(BUTTON_PIN, INT_EDGE_FALLING, &MainWindow::myInterrupt)<0)
{
    printf("cant\n");


}

    while ( 1 ) {
        printf( "%d\n", eventCounter );
        eventCounter = 0;
        delay( 1000 ); // wait 1 second


    }

}
 void MainWindow::myInterrupt()
{
   eventCounter++;
}

error occurs in wiringPiISR function as above title.

[Added code tags ~kshegunov]

[mrjj]

Hi
I think you try to use something that want a callback to a c function

And you try to give it a member function of a class.

That is not the same. ( for a member function, there is a "this")

&MainWindow::myInterrupt will give you the address of a member function.

If the wiringPiISR ask for a normal function pointer this cannot work

Only if the MainWindow::myInterrupt is static.

http://stackoverflow.com/questions/400257/how-can-i-pass-a-class-member-function-as-a-callback

Easy fix. just use a function that is NOT part of main window/any class

Also, as a not for later

while ( 1 ) {}

Is evil and will 100% lag your application.
So when you press button and it calls
on_pushButton_clicked()
it will never respond again.

Do not use such loops in the main thread.

[gauravsharma0190]

@mrjj
i seen the post as in above link
and use simple function
Like

static void myInterrupt();
  #define BUTTON_PIN 0
  volatile int eventCounter = 0;
   // -------------------------------------------------------------------------
  // myInterrupt:  called every time an event occurs


MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
       setenv("WIRINGPI_GPIOMEM", "1", 1);
    ui->setupUi(this);
    wiringPiSetup () ;
    pinMode (0, OUTPUT) ;
}

MainWindow::~MainWindow()
{
    delete ui;
}





void MainWindow::on_pushButton_clicked()
{
    ui->flow2->setText("Hello");


if(wiringPiISR(BUTTON_PIN, INT_EDGE_FALLING, &myInterrupt)<0)
{
    printf("cant\n");


}

    while ( 1 ) {
        printf( "%d\n", eventCounter );
        eventCounter = 0;
        delay( 1000 ); // wait 1 second


    }

}
 static void myInterrupt()
{
   eventCounter++;
}

But same error occurs

[ambershark]

@gauravsharma0190 Now that you took myInterrupt out of your class you should drop the static.. It should be just defined as:
void myInterrupt();

Show us the header or function definition for the wiringPiISR function and we should be able to get it fixed for you.

Also that while (1) loop as mentioned by @mrjj is not going to work at all. You will stall your GUI/event loop, and your entire program. There is no way for the callback to work either unless wiringPiISR puts it in a separate thread. You need to remove that or put it in a thread protected by a mutex or something. Or just use Qt signals and set a timer for 1s that will print your eventCounter. Then there is no while(1) blocking things. And of course you can do it even better and use a signal when the value is changed that will print the new value. Then there is no sleep 1000 at all, which is bad coding. ;)

[gauravsharma0190]

@ambershark
int wiringPiISR (int pin, int edgeType, void (*function)(void)) ;
This function registers a function to received interrupts on the specified pin. The edgeType parameter is either INT_EDGE_FALLING, INT_EDGE_RISING, INT_EDGE_BOTH or INT_EDGE_SETUP. If it is INT_EDGE_SETUP then no initialisation of the pin will happen – it’s assumed that you have already setup the pin elsewhere (e.g. with the gpio program), but if you specify one of the other types, then the pin will be exported and initialised as specified. This is accomplished via a suitable call to the gpio utility program, so it need to be available.

The pin number is supplied in the current mode – native wiringPi, BCM_GPIO or Sys modes.

This function will work in any mode, and does not need root privileges to work.

The function will be called when the interrupt triggers. When it is triggered, it’s cleared in the dispatcher before calling your function, so if a subsequent interrupt fires before you finish your handler, then it won’t be missed. (However it can only track one more interrupt, if more than one interrupt fires while one is being handled then they will be ignored)

This function is run at a high priority (if the program is run using sudo, or as root) and executes concurrently with the main program. It has full access to all the global variables, open file handles and so on.

See the isr.c example program for more details on how to use this feature.
https://github.com/ngs/wiringPi/blob/master/examples/isr.c

[ambershark]

@gauravsharma0190 Try removing the & when passing your myInterrupt function.

I.e.
if(wiringPiISR(BUTTON_PIN, INT_EDGE_FALLING, myInterrupt)<0)

[gauravsharma0190]

@ambershark
it runs
now i want to run the whole thing which is in while loop everytime
so where should i edit it.

[ambershark]

@gauravsharma0190 Well you need to get rid of that while loop entirely.

You can duplicate the while loop's functionality by just adding an output to your interrupt function. Or you could add a GUI label that had a count incremented when the interrupt happened. There are tons of things you could do. They all use signals/slots so no polling which is what you were doing with that while loop (incorrectly, as a loop like that needs a thread, and is still a bad idea even in a thread).

So remove the while loop completely.. and change your interrupt function to this:

void myInterrupt()
{
   qDebug() << "event counter is " << ++eventCounter;
}

Make sure to #include <QDebug>. That should give you console output of any time the event occurs.

Personally I feel the better way is to add a QLabel to your GUI and update it with the current count on every interrupt.

[Rasden Mtz]

somebody can i help me?
/home/pi/Desktop/Qt/Ejemplo-Wiringpi/mainwindow.cpp:18: error: invalid use of non-static member function 'void MainWindow::myInterrupt()'
if(wiringPiISR(4, 2, myInterrupt)<0)
^

[mrjj]

@rasden-mtz
Hi
Just guessing:

the wiringPiISR expects a callback that is a plain free global function. ( a nonmember function)
and you give it a function that lives in MainWindow so it complains that
it has to be a static one (as that is like a global one since it requires no object instance to invoke methods)
so make it static or simply use a nonmember function.

so it has to be like @ambershark shows.