Embedded USB HOST Technology And Its Application In Intelligent Viscometer

As a special computer system, intelligent viscometer needs information communication with the external in many cases, so it needs to extend peripheral equipments. The problem will be solved if USB HOST function realized on intelligent viscometer. Intelligent viscometer which has USB HOST module can extend function by lots of USB device.The contest of this study is the key technology of intelligent viscometer which is jointly developed by Hunan University and Changsha Weite Technology Company. Considering the USB easy to use, the USB HOST function is implemented on intelligent viscometer, by using MSP430F449 as MCU and CH375A as USB HOST controller. It can directly make the data communication between intelligent viscometer and USB micro-printer.This thesis is divided into five chapters. In chapter 1, the development of USB technology, as well as the significance of the research are introduced, and then the work focus of the project is made clear after analyzing the existing embedded USB HOST technology status. In chapter 2, the architecture of USB system, the mechanical and electrical characteristics of USB are introduced, and the protocol of USB data communication is summarized. In chapter 3, the embedded USB HOST development technology which applied to intelligent viscometer is studied, firstly, the performance and structure of USB HOST system, the concept of USB host controller driver and USB core driver are introduced, and then the framework of USB protocol is described. In chapter 4, the structure and workflow of intelligent viscometer based on the capillary gravity are introduced, and then the USB HOST technology design scheme in intelligent viscometer is proposed, at the same time, the USB controller and the hardware circuit design of USB HOST on intelligent viscometer are showed, as well as the the hardware anti-interference design, including USB power design and electromagnetic compatibility design, besides the low power design of hardware is discussed, including chosing low power device, making full use of the low power mode and the working voltage of the system. In chapter 5, the USB controller driver design of intelligent viscometer, which is realized the communication between CH375A and MSP430F449, and the USB core driver design of intelligent viscometer, including the configuration and state management of USB device, USB controller management and the realization of USB transactions, are introduced, and then USB micro-printer driver is showed, at last, the software reliability design of USB HOST is discussed, including the anti-interference design and low power design of software.The experimental results indicate that the USB interface module on intelligent viscometer has anti-interference ability and high accuracy. The topic will promote and drive the application of USB in embedded system.