| Through researching and designing the USB host in the embedded system, describes its working mechanism and implementation structure, and develop the USB interface printers' driver to get the results in hardware and software platform.Firstly, use the real time operating system (RTOS), which is called uC/OS-II system, in AT91SAM9261. The AT91SAM9261 is one of the products about ARM9 of the ATMEL company. And then associate with the actual needs of the monitors, use the AT91SAM9261's own USB host interface (UHP) to achieve the USB host function, and develop the USB host driver program about the USB interface of HP printers, achieve the printing function.This article can be divided into six parts. The first chapter is an introduction, describes the researching in the application background and specific of the intelligent USB interface printers using in the monitors, and noted that the focus of the article. In the second chapter, research the USB system components, communication theory, and the USB device's type, descriptors and standard commands, and focus describe the USB interface printers' specific data transfer type. In the third chapter, research the development technology applied in the monitors, and introduce the USB host controller, the USB host controller driver (HCD), the USB kernel driver (USBD) and the OHCI specification which the USB host should follow. And then make sure the USB host chip. In the fourth chapter, study the types of the printers' interface and the printer control language, and then study the type of the USB interface printer in detail, make sure its data transmission mode. And research the PCL printing language instruction of the HP company deeply. The fifth chapter is the core of the whole article, research how to realize the driver of the USB interface printer, which can be divided into five sections to illustrate. They are the pinter device's class identification request command, the printer device's descriptor type, the printer device's driver design, the printer device's enumeration initialization and the printer data bulk output. The sixth chapter is the functional testing area, mainly test the function of printing.In the actual application, it shows that the USB interface printer has its practical value using in the embedded system. Especially in the medical and clinical fields, it is helpful for making progress in medical technology. |
