【作者】 李升刚；

【导师】 刘映杰；

【作者基本信息】 兰州大学 ， 电路与系统， 2007， 硕士

【摘要】 目前，互联网应用正从以PC为中心转到以嵌入式设备为中心。由于在工业控制、智能仪器、信息家电等领域应用的许多嵌入式设备，它们的对外通讯接口仍然是可操作性强、可靠性高的串口。因此如何将工业中已经大量应用的带有串口的嵌入式设备接入互联网，就成了一项重要而迫切的研究课题。本文介绍了桥接系统的设计背景和相关的知识，比较了当前嵌入式设备实现以太网接入方案的优缺点，以IP2022为系统的网络处理器芯片，设计实现了带有RS-485串口的POS机与以太网之间的桥接系统。该系统硬件主要由IP2022网络处理器，RS-485接口电路、以太网接口电路、JTAG接口电路和电源电路等组成；软件主要由主程序模块、初始化模块和数据协议转换模块组成。本文所实现的桥接系统具有以太网接口功能、RS-485接口功能、看门狗功能、供电状态指示功能、通讯状态指示功能，能够准确地完成以太网和POS机之间的数据传输，可以手动设置系统的IP地址、子网掩码和缺省网关，支持DHCP，可在300～57600bps范围内设置RS-485串口的波特率。该系统具有体积小，功耗低，外围电路简单，开发周期短，开发成本低的特点。经用户测试，满足设计要求，达到了预期的效果，具有一定的实用价值和市场前景。更多还原

【Abstract】 At present, the center of Internet application has just shifted from PC to embedded equipment. In the fields of industrial control, intelligent instrument and information appliance, many embedded equipments have serial interfaces with high maneuverability and reliability for the outer communication. The embedded equipments with serial interfaces are largely applied in the industry. Accordingly, the problem making them connect with the Internet becomes an important and emergent task.The designing background and pertinent knowledge of the bridge system are presented. Now, there are several projects that can implement the connection between embedded equipment and Ethernet. Their merits and flaws are compared. And the dissertation implements the bridge system between POS with a RS-485 serial interface and Ethernet using IP2022.as the processor chip. The hardware of the bridge system includes the IP2022 processor, the RS-485 interface circuit, the Ethernet interface circuit, the JTAG interface circuit and the power circuit, etc. The software includes the modules of main program, initialization and data protocol transform.The functions of the bridge system include Ethernet interface, RS-485 interface, watching dog, power state showing, communicating state showing. It is able to complete exactly the data transmission between Ethernet and POS. Its IP address, Subnet mask, Default gateway can be set manually. It also supports DHCP. Its Baud Rate of RS-485 can be set in the range of 300～57600bps.The advantages of the bridge system are small bulk, low power waste, short development time and low development cost, etc. The result of the test shows that the bridge system can fulfill the design requirements and achieve the anticipative effect. It is of definite applied value and marketable foreground.更多还原