Hi to all,
I'm trying to do ISO OUT transfer on Windows 7 64 bit and every callback
returns LIBUSB_TRANSFER_ERROR.
On Linux transfer is LIBUSB_TRANSFER_COMPLETED, I can read data from my USB
device (Atmel UC3A3256) but
performance is around 300KB/s for 256 ISO endpoint size.
Bulk and Interrupt transfer are working correctly.
This is a part of my Windows test program:
#define ISO_OUT 0x85
#define EP_ISO_SIZE 256
static unsigned char buffer[4096];
*********** detect device, allocate xfer, etc.. *****
libusb_fill_iso_transfer(xfer, handle, ISO_OUT, buffer, sizeof(buffer), 16,
libusb_callback, NULL, 0);
libusb_set_iso_packet_lengths(xfer, EP_ISO_SIZE);
r = libusb_submit_transfer(xfer);
while( r == 0)
{
r = libusb_handle_events(NULL); // or r = libusb_handle_events_timeout(NULL,
&tv); ????
if (r != LIBUSB_SUCCESS)
break;
}
*****cancel transfer etc*****
My USB device sends/receives every 2mS 3072bytes (1.5MB/s) and with BULK I have
no problem in down stream but in upstream timing is
issue. My questions are:
- how much speed can I expect in theory with ISO type of transfer for 256byte
ISO ep size?
- is my test code correct or do I need to change/add something?
Goran
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