New class --> signal and slots

TMJJ

Dear all,

This is probably a very stupid question, but I can't get my head around it.
I have a class which is called Canbus. This class is called from within my Mainwindow.cpp

In the Canbus class I initialize the canbus settings.

void Canbus::Can_Init()
{
    /*START CAN0*/
    QString cmd1 = "ip";
    QStringList opt1;

    /*ip link set can0 up type can bitrate 250000*/
    opt1 << "link"<< "set"<< "can0"<< "up" << "type" << "can" << "bitrate"<< "250000";
    proc1.start(cmd1,opt1);

    QString cmd2 = "ifconfig";
    QStringList opt2;

    /*ifconfig can0 up*/
    opt2 <<"can0"<< "up";
    proc2.start(cmd2,opt2);

    QString cmd3 = "candump";
    QStringList opt3;
    opt3 << "can0";
    proc3.start(cmd3,opt3);

}

Now I have another function in this class which is called dataReady().
I wish to do the following:

connect(&proc3,SIGNAL(readyRead()),this, SLOT(dataReady()));

I used this before when I was working only into the mainwindow.cpp.
If I want to connect those to in a class, how shouldI do this?

The following file is my canbus.h file

#ifndef CANBUS_H
#define CANBUS_H

#include <QtGui>
#include <QProcess>
#include <QObject>
class Canbus
{
     Q_OBJECT

public:
    Canbus();
    ~Canbus();

public slots:
    void dataReady();

private:
    void Can_Init();
    int buttonPushed(void);


    QProcess proc1;
    QProcess proc2;
    QProcess proc3;
    QProcess proc4;
    QProcess proc5;
    QProcess proc6;
};

#endif // CANBUS_H

This is my canbus.cpp file

#include "canbus.h"


void Canbus::dataReady()
{
    while(proc3.bytesAvailable()){

        QString in = proc3.readLine();
        QString out;

        QString DataString[8];
        QString CANbus;
        QString IDstring[8];
        QString IDString;
        long IDdec[8];
        QString IDhex;
        unsigned long ID;
        QString dataBytes;
        int dataCAN[8];
        QString DataStringL[4];
        short dataCANL[4];
        QString printOut;
        QString regString;
        bool ok;
        int regNumb;
        QString DataHEX;

        QRegExp reg("  can([01])  ([0-9A-F])([0-9A-F])([0-9A-F])([0-9A-F])([0-9A-F])([0-9A-F])([0-9A-F])([0-9A-F])   \\[([0-9]+)\\]  ([0-9A-F]+) ([0-9A-F]+) ([0-9A-F]+) ([0-9A-F]+) ([0-9A-F]+) ([0-9A-F]+) ([0-9A-F]+) ([0-9A-F]+)");

        if(reg.indexIn(in)>=0){


            regNumb = 11;
            for(int n=0;n<8;n++)
            {
                regString = "%" + QString::number(regNumb);
                DataString[n] = regString;
                DataString[n] = DataString[n].arg(reg.cap(regNumb));

                DataHEX = "0x" + DataString[n];
                dataCAN[n] = DataHEX.toUInt(&ok, 16);

                regNumb++;

            }

            if((dataCAN[0])==0x15)
            {
                printOut = "GO";



                for (int n=0;n<8;n++)
                {
                    qDebug() << DataString[n];

                }
            }
            else if ((dataCAN[0])==0x15 & (dataCAN[1])==0x16 & (dataCAN[2])==0x1E & (dataCAN[3])==0xCF & (dataCAN[4])==0x00 & (dataCAN[5])==0x09 & (dataCAN[6])==0x71 & (dataCAN[7])==0x00)
            {



            }
        }


    }
}

void Canbus::Can_Init()
{
    /*START CAN0*/
    QString cmd1 = "ip";
    QStringList opt1;

    /*ip link set can0 up type can bitrate 250000*/
    opt1 << "link"<< "set"<< "can0"<< "up" << "type" << "can" << "bitrate"<< "250000";
    proc1.start(cmd1,opt1);

    QString cmd2 = "ifconfig";
    QStringList opt2;

    /*ifconfig can0 up*/
    opt2 <<"can0"<< "up";
    proc2.start(cmd2,opt2);

    QString cmd3 = "candump";
    QStringList opt3;
    opt3 << "can0";
    proc3.start(cmd3,opt3);

}

So I have no idea on how to connect the signal and the slot in a class. I searched in the documentation of qt but I don't understand it completely.

Thanks in advance,
Kind regards,
Toon Mertens

Pablo J. Rogina

@TMJJ did you take a look at the CAN Bus example already? I guess using the QCanBusDevice and QCanBusFrame classes will simplify your development.
You can even look at this webinar from ICS

TMJJ

@Pablo-J.-Rogina
Thanks for the reply. Yes indeed that would be the best way. The issue is that I'm developping this for an embedded system which only support qt4.8.
So I can't use it.

That's why I'm setting this up.

Kind regards

JonB

@TMJJ

So I have no idea on how to connect the signal and the slot in a class

Maybe I'm missing the point, but why can't you put your connect line into, say, Can_Init()?

TMJJ

@JonB
Yes that I tried as well. I did the following :

void Canbus::Can_Init()
{
    /*START CAN0*/
    QString cmd1 = "ip";
    QStringList opt1;

    /*ip link set can0 up type can bitrate 250000*/
    opt1 << "link"<< "set"<< "can0"<< "up" << "type" << "can" << "bitrate"<< "250000";
    proc1.start(cmd1,opt1);

    QString cmd2 = "ifconfig";
    QStringList opt2;

    /*ifconfig can0 up*/
    opt2 <<"can0"<< "up";
    proc2.start(cmd2,opt2);

    QString cmd3 = "candump";
    QStringList opt3;
    opt3 << "can0";
    proc3.start(cmd3,opt3);
    
    QObject::connect(&proc3,SIGNAL(readyRead()),this, SLOT(dataReady()));

}

So I added it to the bottom. Then I get the following error:

/home/whooper/Documents/Tractor/Fendt_CAN_seeder/Fendt415_CAN_Seeder_V1_0/canbus.cpp:93: error: no matching function for call to 'QObject::connect(QProcess*, const char [13], Canbus* const, const char [13])'

I have no clue what I'm doing

Christian Ehrlicher

Canbus must derive from QObject.
And you should do your connect before QProcess::start(). And you should wait for process to finish until proceeding further.

aha_1980

@TMJJ

I hope you are not going to interpret the output of candump in your application to receive CAN frames!

SocketCAN provides a userspace API which can be perfectly used from C/C++ programs.

As SocketCAN is open source, there are lots of examples how to do this, like the SocketCAN plugin of QtSerialBus or the source code of candump.

Regards