Silicon Laboratories Stepper Machine Specifications download pdf (Page 40)

Device Classes

 Device classes group common interfaces together

 Class definitions specify the number and types of endpoints

 May define data formats

 May define functions or capabilities of devices within the class

 Some types of defined classes

 Human interface class

 Communications device class

 Hub class

 Printer class

 Mass storage class

 Audio class

An additional set of specifications has been added to the overall USB 2.0

specifications. These additional specifications provide standard functionality using

a predefined set of rules to set up and enumerate as well as the endpoint types and

transfer types required. Along with defining exactly how the device will be

configured, there is also an associated driver already integrated to the OS. That

alleviates the need to write a custom drivers to suit the application. If the

application data bandwidth requirements can fit within one of these pre-defined

classes defined by the USB consortium then you can use that class and the driver

that is built into the OS. For example, we can configure our device to enumerate as

a Human Interface Device (HID) class and transfer data according to the HID

specification. The driver that communicates with our Windows application is

already a part of Windows and we didn’t have to write any driver code. Another

application is the use of the Communications Device Class (CDC) that can be used

for USB to UART applications and uses the built in Windows driver usbser.sys.

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Silicon Laboratories Stepper Machine Specifications Page 40