One way of distinguishing identical USB devices is to use the
locationID property. Once you have discovered USB devices from
IOKit, you can look for this property. This value is unique for
each device -- and it will remain constant across reboots if the USB
topology isn't changed.
Your framework will want to keep some kind of object (or handle)
to represent the device. Whether this is a real C++ Object, or
just an index into an internal table, or the locationID is entirely up
to you.
If you're asking if you need to open unique files to access USB
devices on MacOS X, the answer is no. If I've totally
misunderstood what you're asking, perhaps you can clarify what help
you need.
Regards,
David Ferguson
At 4:19 PM -0600 3/29/05, Michael Krugman wrote:
Hi
List:
I'm working on a
USB device that uses the EZ-USB AN2131 chip. I am writing a
framework which will eventually serve as a USB driver for the device.
The manufacturer insists that in order for this device to work under
OS X, that a handle to the device must be created and this handle is
referenced in every command sent to it. They say the reason is
that more than one device can be plugged into the usb box. They
also say that without a created handle to the device that this will
not work. Below is the Windows code that they supplied.
They explain that they create the handle by creating a file and the
code is shown below.
bool
OpenUsbDriver(){
char completeDeviceName[64] =
"";
strcat
(completeDeviceName,"\\\\.\\");
strcat
(completeDeviceName,"xxxxx-0");
hDeviceHandle = CreateFile( completeDeviceName,
GENERIC_WRITE,
FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
0,
NULL);
if (hDeviceHandle == INVALID_HANDLE_VALUE)
{
return (false);
}
return (true);
}
Is there a way to duplicate this in OS
X? Or is there another way to create the handle? Help is
appreciated.
Sincerely,
Mike Krugman
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