基于SL811HST的嵌入式USBHOST模块的设计

发布时间：2018-09-04 12:58

【摘要】：随着计算机技术的发展，对一主机为中心的计算机软件的复杂性、拓扑结构以及相对嵌入式系统的功率要求较高，而同时对降低了主机对电力的需求。本文着重采用理论分析与的方法提出了对Host系统的改进：以最优的性价比，将USB Host系统建立在资源稀缺和无操作系统的嵌入式系统中。对改进后的系统进行测试，结果可以发现，，改进后的系统性能克服了传统Host系统的缺点，满足现在广大用户的需求。基于理论基础，可以独立于操作系统而实现嵌入式USB主机应用程序，USB及其所支持的设备类协议，所采用的相关的传输协议的复杂性，对于计算机存储器、运算速度等有比较高的要求，建立嵌入式USB Host系统的关键是，如何更好的解决单片机的有限资源与支持复杂USB协议之间的矛盾。要实现基于单片机嵌入式USB Host系统的开发，存在一些技术难点：特定的应用需求如何通过单片机本身的有限的资源处理，特定USB设备的信息如何利用裁剪USB协议处理， USB Host系统功能如何实现等。目前主要有两种方案解决这个问题：一是内部集成USB内核的MCU:控制模块并将其作为芯片上外设部分的MCU微控制器，其包括一个集成的USB物理层，基本不需要任何外部元器件。不足之处是所采用的MCU芯片必须是特定的，从而限制了其应用功能的实现，不能满足对应用广泛的嵌入式系统设计的需求，并且需要专门的开发工具，开发费用高。二是32位MCU＋RTOS。因为高性能处理器/微控制器在这种情况下可以完成许多繁琐的功能，包括USB主机功能。处理器/微控制器性能越高，其价格也越高，而且对其的开发需要较长的时间， RTOS开发平台比较贵，一般企业难以实现，发展技术门槛高，实现难度比较大。本课题提出了一种全新方案，解决了上述两种方案的不足之处。我们可以直接使用MCU+USB主控芯片，前者可对后者进行驱动，而且可直接完成对Mass Storage类USB设备的访问。该方案的优点在于使用了8位的MCU，从而简化了硬件电路、减少了外围器件、降低了系统成本。通过执行虚拟软件模块，CPU可直接驱动普通的I/O口来实现硬件外设功能。
[Abstract]:With the development of computer technology, the complexity of a host computer software, the topology and the power requirement of the embedded system are higher, while the power demand of the host is reduced. In this paper, the improvement of Host system is put forward by using the method of theoretical analysis and analysis. The USB Host system is established in the embedded system with scarce resources and no operating system with the optimal performance-price ratio. After testing the improved system, it can be found that the improved system performance overcomes the shortcomings of the traditional Host system and meets the needs of the majority of users. Based on the theory foundation, we can realize the embedded USB host application program and its supporting device class protocols independently of the operating system. The key to the establishment of embedded USB Host system is how to solve the contradiction between the limited resources of single chip computer and the support of complex USB protocol. In order to realize the development of embedded USB Host system based on single chip computer, there are some technical difficulties: how to deal with the specific application needs through the limited resources of the single chip microcomputer itself, How to use the clipped USB protocol to deal with the, USB Host system function of a specific USB device. At present, there are two solutions to this problem: one is to integrate the MCU: control module of the USB kernel and use it as the MCU microcontroller of the peripheral part of the chip, which includes an integrated USB physical layer, and does not require any external components. The shortcoming is that the MCU chip used must be specific, which limits the implementation of its application function, and can not meet the needs of the widely used embedded system design. It also needs special development tools, and the development cost is high. The second is 32-bit MCU+RTOS.. Because high performance processors / microcontrollers can perform a lot of tedious functions in this case, including the USB host function. The higher the performance of processor / microcontroller is, the higher its price is, and it takes a long time to develop the processor / microcontroller. The RTOS development platform is expensive, the enterprise is difficult to realize, the technical threshold is high, and the realization is difficult. In this paper, a new scheme is proposed to solve the shortcomings of the above two schemes. We can directly use MCU USB master control chip, the former can drive the latter, and can directly complete access to Mass Storage USB devices. The advantage of this scheme is that the 8-bit MCU, is used to simplify the hardware circuit, reduce the peripheral devices and reduce the system cost. By executing the virtual software module CPU, the common I / O port can be directly driven to realize the hardware peripheral function.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TP368.1

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