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List:       libftdi
Subject:    Re: Multiple interface issues
From:       Steve Soloski <ssoloski () biometrica ! com>
Date:       2014-05-31 19:52:59
Message-ID: 538A331B.60900 () biometrica ! com
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On 05/30/2014 09:32 PM, Xiaofan Chen wrote:
> On Fri, May 30, 2014 at 10:17 PM, Steve Soloski <ssoloski@biometrica.com> wrote:
>> Well, after banging my head against the wall all day yesterday, I've figured
>> out what's happening...
>>
>> In all of my installing/uninstalling of the USB driver - trying both
>> libusbK-inf-wizard and zadig - I eneded up with both libusb0.dll and
>> libusbK.dll on my system, in addition to the WinUSB that I wanted. Not quite
>> sure how they all got installed, but when I deleted both of them (and only
>> used the WinUSB driver) then this issue went away. Not sure what was causing
>> the issue, but at least it's resolved!
>>
> Hmm, that is strange. libusbk-inf-wizard and Zadig both install libusb0.dll
> and libusbK.dll to be compatible with libusb-win32 and libusbK.
>
> As for libusb Winodws backend, it will work either with libusbK.dll (to
> support libusb0.sys, libusbK.sys and WinUSB) or without libusbK.dll
> (only works with WinUSB). The code path will be a bit different.
>
> Are you using the latest release version of libusb (1.0.18)?
>
>
>

Just rebuilt libusb (1.0.18) and libFTDI (1.1) from the tarballs; cross 
compiling on Linux using x86_64-w64-mingw32.

Same result when running under Win8 x64 - if libusbK.dll is in my path 
then I get the following error when trying to open the device more than 
32 times:

opening device 28 of 50...
opening device 29 of 50...
opening device 30 of 50...
opening device 31 of 50...
opening device 32 of 50...
ftdi_usb_open failed: -5 (unable to claim usb device. Make sure the 
default FTDI driver is not in use)

However, I noticed something interesting...

When I try to connect to my device I always use Interface B first (it's 
my control channel and needed to init my device); Interface A is only 
used (in a separate thread) when trying to capture images. So, trying to 
open my device like this:

     for (i=0; i<50; i++) {
       struct ftdi_context *ftdi = ftdi_new();
       ftdi_set_interface(ftdi, INTERFACE_B);

       fprintf(stderr, "opening device %d of 50...\n", i);
       ret = ftdi_usb_open(ftdi, 0x0403, 0x7C38);
         ...
       ret = ftdi_usb_close(ftdi);
       ftdi_free(ftdi);
     }


will fail after 32 open/closes with the error above.

However, I just tried not setting the interface to B and it works fine 
and doesn't fail - even with libusbK.dll! Seems like there's something 
about not having Interface A claimed that is causing issues... of 
course, since I always open with B that doesn't do me much good! ;)


Steve


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