Hi,
I extended the listdevs example with libusb_get_config_descriptor() and in most
cases I get the error "LIBUSB_ERROR_NOT_FOUND". As far as I know, every USB
device should support this feature.
Try it yourself.
I'm using Windows XP and libusbx 1.0.14.10586.
Best regards
Stefano
/*
* libusbx example program to list devices on the bus
* Copyright © 2007 Daniel Drake <d...@gentoo.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdio.h>
#include <sys/types.h>
#include "libusb.h"
static void print_devs(libusb_device **devs)
{
libusb_device *dev;
int i = 0;
while ((dev = devs[i++]) != NULL) {
struct libusb_device_descriptor desc;
struct libusb_config_descriptor *config;
int r = libusb_get_device_descriptor(dev, &desc);
if (r < 0) {
fprintf(stderr, "failed to get device descriptor");
return;
}
printf("%04x:%04x (bus %d, device %d)\n",
desc.idVendor, desc.idProduct,
libusb_get_bus_number(dev),
libusb_get_device_address(dev));
r = libusb_get_config_descriptor(dev, 0, &config);
if (r != 0) {
fprintf(stderr, "failed to get config descriptor:
%s\n", libusb_error_name(r));
//return;
} else {
printf("Max Power: %u mA\n", config->MaxPower * 2);
libusb_free_config_descriptor(config);
}
}
}
int main(void)
{
libusb_device **devs;
int r, i;
ssize_t cnt;
r = libusb_init(NULL);
//libusb_set_debug(NULL, LIBUSB_LOG_LEVEL_DEBUG);
if (r < 0) {
libusb_error_name(r);
return r;
}
cnt = libusb_get_device_list(NULL, &devs);
if (cnt < 0)
return (int) cnt;
print_devs(devs);
libusb_free_device_list(devs, 1);
libusb_exit(NULL);
return 0;
}
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