Implementation Of USB OHCI Host Stack Based On μC/OS-Ⅱ

The Universal Serial Bus (USB) is an external serial communication interfacestandard of computer. It has been one of the absolutely necessarily interfaces ofmodern computers. The Open Host Controller Interface (OHCI) is an USB hostcontroller interface specification which has also been widely used in embedded system.The μC/OS-Ⅱ is a simple and effectively real-time operating system used in embeddedproducts. The USB OHCI host stack based on μC/OS-Ⅱ provides the access ability toUSB devices for embedded products whose resource is very limited, because of itsvery low resource usage. The existing USB OHCI host stack usually doesn’t meet therequirements of the actual product in function, resource usage, cost andmaintainability.This paper provides a relatively complete implementation of an USB OHCI hoststack based on μC/OS-Ⅱ operating system for AT91SAM9260hardware platform. First,the paper provides the architecture design and the module definition for the system.Second, the paper provides the implementations of each module: Host ControllerDriver, USB Driver and Class Driver. The Host Controller Driver module implementsthe USB low-level data transfer function, the USB Driver module implements the USBcommunication function and the USB device management function, and the ClassDriver module implements the Mass Storage Class protocol and HID Class protocol.Last, the paper builds a test bench and provides several test cases to verify the validityof the USB OHCI host stack. The experiment result shows that the USB OHCI hoststack has achieved the design requirements in its feasibility and validity.