A Step-By-Step Guide to Developing USB I/O Devices
This guide takes a step-by-step approach to the development process and an example design is implemented using this process.
This example is a simple buttons and lights design; it includes an 8 bit input port and an 8 bit output port that can be controlled by the PC host or from the I/O device.
This design is easily expanded to cover other applications.
Other examples are available.