Design And Implementation Of USB Printer Driver Of Embedded System

With the growing popularity of USB interface, it not only became a standard interface for PC, but also became the interface more and more supported by many embedded devices. By adding to USB host controller, embedded devices can be connected to an external USB printer, human interface devices (mouse, keyboard, etc.), flash memory and other external devices, which are connected to PC likewise, thereby greatly enhancing the scalability of embedded devices and usability. Based on the analysis of requirement which embedded devices to connect USB printer to print reports, detailed design and coding of the USB printer driver are made in this article. So the embedded device can be connect to a printer via USB cable, user can print out the account list report via the user interface of the embedded devices. Modular software architecture is also designed based on the software requirement, the software architecture includes:USB host control drive, USB device drivers, I/O management system and the application layer. The printer driver is implemented in this software architecture.In this paper, the following aspects of the work are carried out1. USB technology, the development process, an overview of USB architecture, bus protocol and data streams are introduced. USB devices and USB device enumeration process are described. OTG technology is also introduced in this article, OTG is a supplement to USB protocol and fully compatible with USB protocol.2. A software requirement is developed based on the user requirement. Two kinds of solution, USB host controller and OTG Dual-role device are given. The USB host solution is determined as the final design based on the compare of the two solutions. Detailed system diagram and description of each module are also given.3. The overview of USB host system is reviewed. USB host system includes the USB driver (USBD) and the host controller driver (HCD) which has a tight relationship with the hardware of USB controller. The code the USB driver is implemented. The data structure of USB driver, initialization and interface functions are described in detail.4. In this paper, the USB printer driver is implemented by C language in real-time operating system-nucleus. The related data structure of USB printer driver is introduced. Its initialization process, the interface functions are analyzed in detail. It also describes how to write data to the printer and read the printer status information.5. The I/O management system and its interface functions are introduced. Coding of I/O interface module of the printer driver. As well as a application design of printable report are generated...