PATHHardware Documentation > USB Devices > Mac OS USB DDK API Reference

Improved Functionality For USB Control Requests

A new flag was added to the USBDeviceRequest function to allow for USB control transactions addressed to an interface or endpoint of a device. The new feature allows the call to be made without the driver explicitly knowing the number of the endpoint or interface before the call is made. The USL now fills in the interface or endpoint number when an interface or pipe reference is passed in with the call.

To use the new feature, you specifiy the flag kUSBAddessRequest in the usbFlags field of the USBDeviceRequest function. If the recipient field in BMRequestType is an endpoint or interface, the relevant endpoint or interface number is derived from the pipe or interface reference passed in the usbReference field. The appropriate interface or endpoint number is put into the usbWIndex field before the control transaction call takes place.

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