Design of a MicrocontrollerBased Ethernet （MicrocontrollerBased以太网的设计）.pdfVIP

Design of a Microcontroller-Based Ethernet Messaging Device David Clausen, Stanford University December 13, 2000 Abstract: I describe the design of a microcontroller-based hardware device which has a standard RJ45 Ethernet port and an LCD display. The device will receive and decode UDP/IP datagrams, and display the contents of those datagrams as text on the LCD display. 1. Introduction 1.1 Description This report is offered as documentation of my final project in EE281, Embedded System Design Laboratory, in the Fall quarter of 2000 at Stanford University. For my final project, I wanted to use an AVR AT90S8515 microcontroller to communicate over a standard Ethernet network. As a demonstration application, I decided to make a device which could receive UDP datagrams on an Ethernet interface, and display the contents on an LCD display. I also wrote a small perl script which prompts the user for text input, and sends that text to the device as a properly-formatted UDP datagram. This script can be run from a Windows or Unix computer. For my in-class demonstration, I had a trivial network consisting of a laptop Windows 98 computer, the microcontroller device, and a 10-base-T crossover cable connecting the two. However, since the device communicates using standard IP, it should have no problems communicating over the Internet at large. 1.2 Photographs Figure 1: Device POST shows NICs MAC Figure 2: Compose a message in Win98, address and pre-programmed IP address and send it via UDP over the Ethernet... Figure 3: The device receives the UDP message, and displays the contents as ASCII 2. High Level Design The project uses a generic NE2000-compatible ISA Ethernet card which I bought at a local electronics store. I have connected the card in such a way that it can be controlled by the AVR using 16 logic lines (8 bi-directional data, 5 address, 2