Re: [Libusb-devel] Can't Send Control Messages to usb device in Windows

[Xiaofan C. <xia...@gm...>]

On Tue, Apr 20, 2010 at 6:26 AM, Xiaofan Chen <xia...@gm...> wrote:
> On Tue, Apr 20, 2010 at 6:12 AM, Jason Kotzin <jas...@gm...> wrote:
>> Yes, I do receive something that says, attempting to open r/w access, did
>> not work, assuming HID keyboard or mouse.
>> However, isn't that the same thing that xusb is doing?  I see control
>> transfer in there that send and receive data.
>
> I believe you can do control transfer with the HID device, even with the
> system keyboard and mouse (but not interrupt transfer), that is
> what xusb is doing.

I made a mistake here. Yes it can do control transfer, but only for
the feature report.

> Firstly please update to the latest version by using git.
>
> To help us (and you), please post the HID report descriptor. And please
> post your test program and the debug message.
>
> When you do the following, the report ID is 0. Is that the case? Is your
> keyboard a USB composite device?
> libusb_control_transfer(handle,
> LIBUSB_ENDPOINT_OUT|LIBUSB_REQUEST_TYPE_CLASS|LIBUSB_RECIPIENT_INTERFACE,
> HID_SET_REPORT, (HID_REPORT_TYPE_OUTPUT <<8)|0x00, 0 , output_report, 06,1000));
>

Ah, that is an output report. So maybe this is not possible.

You can use feature report (Control-IN and Control-Out) for the system
keyboard/mouse. But for output report, that is problematic. For Input
report, you can use Raw Input.

http://www.lvr.com/hidfaq.htm
1) Why do I receive "Access denied" when attempting to access my HID?

Windows 2000 and later have exclusive read/write access to HIDs
that are configured as a system keyboards or mice. An application
can obtain a handle to a system keyboard or mouse by not requesting
READ or WRITE access with CreateFile. Applications can then use
HidD_SetFeature and HidD_GetFeature (if the device supports
Feature reports).

2) How can applications receive Input reports from a system mouse or keyboard?

The Windows raw input API enables applications to read Input reports
when communicating with system mice and keyboards.

-- 
Xiaofan http://mcuee.blogspot.com