Problem getting libusb datarecieved event to send signal

hi the title may busbcom = new UsbCom();
connect(usbcom, SIGNAL(error(QString)), SLOT(usbError(QString)));
usbcom->start();e a little weird but i wasnt sure what to call it.

il try to explain what im trying to do.

i am trying to get data from the usb device with libusb_handle_events function
in my main class i use this code to start the thread for usb communication:

Code:

---

usbcom = new UsbCom();
    connect(usbcom, SIGNAL(error(QString)), SLOT(usbError(QString)));
    connect(usbcom, SIGNAL(dataRecieved(QString)), SLOT(usbDataRecieved(QString)));
    usbcom->start();

---

UsbCom class:

Code:

---

#include "usbcom.h"
#include <QtGui>
#include "/usr/local/include/libusb-1.0/libusb.h"
#include "dataemit.h"
#include <QApplication>
 
#define idVENDOR	0x0483
#define idPRODUCT	0x5750
#define EP_INTR_OUT	( 1 | LIBUSB_ENDPOINT_OUT)
#define EP_INTR_IN	( 1 | LIBUSB_ENDPOINT_IN )
 
UsbCom::UsbCom()
{
}
 
void UsbCom::run()
{
    int r;
    int transf;
    unsigned char data[2]={2,5};
    r = libusb_init(NULL);
    if (r < 0)
    {
        emit error("Failed to initialize USB!");
        exit(1);
    }
 
    libusb_device_handle *devh = libusb_open_device_with_vid_pid(NULL, idVENDOR, idPRODUCT);
 
    if(!devh)
    {
       emit error("Could not locate device");
       exit();
    }
 
    r = libusb_kernel_driver_active (devh, 0);
 
    if (r != 0)
    {
        if(r==1)
        {
            r = libusb_detach_kernel_driver(devh, 0);
            if (r > 0)
            {
                emit error("some other random error:"+ QString::number(r));
                exit(1);
            }
        }
    }
 
    r = libusb_claim_interface(devh, 0);
 
    if (r < 0)
    {
        emit error("usb_claim_interface error"+ QString::number(r));
    }
 
    r = libusb_interrupt_transfer(devh, EP_INTR_OUT, data, sizeof(data), &transf,50);
 
    emit error("did it work? r:" + QString::number(r));
 
    irq_transfer = libusb_alloc_transfer(0);
    unsigned char irqbuf[2];
 
    libusb_fill_interrupt_transfer(irq_transfer, devh, EP_INTR_IN, irqbuf,sizeof(irqbuf), ep_irq_in_cb, NULL, 0);
    r = libusb_submit_transfer(irq_transfer);
 
    while(1)
    {
        r = libusb_handle_events(NULL);        
    }
}
 
void UsbCom::dataRecieve()
{
}
 
void ep_irq_in_cb(libusb_transfer *transfer)
{
    if(transfer->status != LIBUSB_TRANSFER_COMPLETED)
    {
     // fprintf(stderr, "uncompleted transter\n");
    }
 
    //[COLOR="red"]dont know what code goes here, try to call UsbCom::DataRecieve[/COLOR]
 
    if (libusb_submit_transfer(transfer) < 0){
      fprintf(stderr,"couldnot resubmit irq \n");
                exit(1);
    }
 
}

---

the problem is that as you can see the
void ep_irq_in_cb(libusb_transfer *transfer) function is not in the UsbCom class. but when the code executes i need to call the UsbCom::DataRecieve() function so that it connects to the slot in my main thread.

if anyone can help me i would be very gratefull.

Sisco

what is the protype of libusb_fill_interrupt_transfer()?
Usually call back set functions take also a 'user param' to allow access to a user class.
What is the 'NULL' parameter?

Quote:

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Originally Posted by high_flyer

what is the protype of libusb_fill_interrupt_transfer()?
Usually call back set functions take also a 'user param' to allow access to a user class.
What is the 'NULL' parameter?

---

from libusb documentation:

Code:

---

static void libusb_fill_interrupt_transfer  	(  	struct libusb_transfer *   	 transfer,
		libusb_device_handle *  	dev_handle,
		unsigned char  	endpoint,
		unsigned char *  	buffer,
		int  	length,
		libusb_transfer_cb_fn  	callback,
		void *  	user_data,
		unsigned int  	timeout	 
	) 			[inline, static]
 
Helper function to populate the required libusb_transfer fields for an interrupt transfer.
 
Parameters:
    	transfer 	the transfer to populate
    	dev_handle 	handle of the device that will handle the transfer
    	endpoint 	address of the endpoint where this transfer will be sent
    	buffer 	data buffer
    	length 	length of data buffer
    	callback 	callback function to be invoked on transfer completion
    	user_data 	user data to pass to callback function
    	timeout 	timeout for the transfer in milliseconds

---

the NULL parameter is the user_data param i thougnt since i didnt have anything i wanted to send with it i just used NULL.

after some searching on the web i tried this:

Code:

---

irq_transfer = libusb_alloc_transfer(0);
        unsigned char irqbuf[2];
        libusb_fill_interrupt_transfer(irq_transfer, devh, EP_INTR_IN, irqbuf,sizeof(irqbuf), ep_irq_in_cb, &a, 0);
        //libusb_fill_control_transfer(irq_transfer, devh, irqbuf, ep_irq_in_cb, NULL,0);
        r = libusb_submit_transfer(irq_transfer);
 
        while(1)
        {
            if (a == 1)
            {
                emit dataRecieved("o.o");
                a = 0;
            }
            r = libusb_handle_events(NULL);
        }

---

Code:

---

void ep_irq_in_cb(libusb_transfer *transfer)
{
    if(transfer->status != LIBUSB_TRANSFER_COMPLETED)
    {
     // fprintf(stderr, "uncompleted transter\n");
    }
    else
    {
 
        int *data = transfer->user_data;
        *data = 1;
    }
    if (libusb_submit_transfer(transfer) < 0){
      fprintf(stderr,"could not resubmit irq \n");
                exit(1);
    }
 
}

---

wich gave me this error:

Code:

---

/home/sisco/Documents/School/Project 3/Project Software/Project/usbcom.cpp:93: error: invalid conversion from ‘void*’ to ‘int*’

---

Quote:

---

the NULL parameter is the user_data param i thougnt since i didnt have anything i wanted to send with it i just used NULL.

---

Read my last post again.
As you can see, my prediction was correct, and the parameter was user data.
You should change the call back function to take the user data parameter too, and then you can pass your Usb class pointer to it, and call the Usb object methods in it.

yes, you were right fixed it now the way i posted before. i just had to cast the user data to an int.

thank you verry much.

sisco

hi every body,
I have a questoin about the libusb, libusb_fill_iso_transfer function.
What is the libusb_transfer_cb_fn callback, field in this function?
Is it a function I myself should write it or it is default function and there is no need to write it?

tanks
havij000