CHAPTER 15 USER-SPACE USB DRIVERS · LowLatencyWriteIsochPipeAsync: Performs a write to an isochronous endpoint on the USB device. The parameters to this method extend those of the method WriteIsochPipeAsync to include a parameter named updateFrequency that specifies how often the I/O Kit should update the frame list during the transfer (specified in milliseconds). The IOUSBLowLatencyIsocFrame array and the source buffer must both have been allocated by the method LowLatencyCreateBuffer. Summary · For certain types of devices, including USB devices, the I/O Kit makes it possible to forgo a kernel driver and implement the driver completely in user space. For the end user, this provides a much better experience. Not all USB devices are suitable for a user-space driver. A device that needs to be used by the system itself, such as a system-wide audio device or a USB storage device, must be implemented in the kernel. The I/O Kit provides a user-space library known as IOUSBLib that an application uses to interact with a USB device. The IOUSBLib provides a user- space equivalent to the IOUSBDevice and IOUSBInterface kernel classes, known as IOUSBDeviceInterface and IOUSBInterfaceInterface, respectively. An application can watch for the arrival and removal of the USB devices it supports by creating a matching dictionary and installing a notification callback, as described in Chapter 5. Once an application has been notified that a USB device or a USB interface it is interested in has been attached to the computer, it · · ·