The Design of USB Interface in

This paper introduces the way using AN2131SC to implement USB interface to replace parallel interface in Stored Program Control switching system for teaching. It presents the design of hardware, firmware, device driver and client application,
therefore providing an instance for USB peripheral development especially in replacing parallel interface with USB interface.
Key Words：USB interface；Stored Program Control；Firmware；Device driver
The Stored Program Control switching system for teaching designed by Huazhong University of Science and Technology has been widely used in quite a number of colleges and universities around China.
The system uses a PC as console to implement operation and control, so it does not include an MCU itself. The system communicate with a PC via parallel port, but parallel port does not support hot swap.
Moreover, a PC has only one parallel port, so it cannot support the system and other peripherals using parallel port simultaneously. In order to overcome these
disadvantages, the USB version has been developed. USB supports hot swap, and it is more reliable than parallel port in data transfer[1]. The paper introduces
the IC AN2131SC first, and then presents the design flow of circuit, firmware, driver and client application.