Internet network embedded system design
Date 2000-4-23 Author's Electricity Automation Research Institute Liang Heqing Content Network will start from service to the application network. The network is the service nature, so it is a server / client structure on its architecture. The network develops from the local area network to the WAN, and then go to the Internet. The Internet is the largest global network. Online transfer is data stream, sound flow, and video stream, which is collectively referred to. Information needs to follow and corresponding protocols at all levels in the transmission process. In order to compress the traffic of the Internet online information, the information submitted to the web uses the HTML hypercraft marker format, and any of the recipients on the Internet, you can use any HTML browser, you can see it on the web page, hear or Other forms of presence of information. In other words, in the Internet, information published by the web server, any client, can read information on the web page with any web browser. The post-PC age exploded online information (Information Appliance, also known as information appliance), such as Web Personal Digital Assistant (PDA), Web Visual Phone, mobile phone GPS or W-CDMA product, TV top view box, Embedded equipment such as TV conference machines, digital cameras, all requires Internet network, which should have embedded the hardware and software required for hanging nets. The rapid progress of the Internet and wireless backbone network makes the communication performance, quality and reliability of packet switching technologies have been steadily improved, and the reliability of network applications should be trustworthy. In the past, a large number of 8/16-bit microcontrolled embedded equipment such as instrumentation, data acquisition, display, process control, industrial automation, home automation, etc. have reached the convenience of the network. They will become the development of the INTERNET network, and meet the "network service" to extend the tide of "network application". What is the meaning of small devices hang on the Internet? What is the great and far-reaching significance of many small devices on the Internet? In the past, the distal display and control of the dedicated communication line in the distant collection field is not, but only the communication media should be dedicated, the communication protocol must write, supporting software and hardware to design it. Today, the distant display and control of embedded devices can basically solve the problem, and the level is high. · There is no need for a private communication line, ready-made global network is passed away from the sea to the end of the horizontal corner; · The speed of the speed is stunned; Out-of-art, any web browser can read incorrectly, large to 10MByte's complete desktop browser, small to 600kbyte Mosaic browser, whether it is Microsoft's browser or Netscape browser. Information is directly reflected on colorful webpages, the form can be data, text, image, table or voice, real-time data automatically update, the device's operation will have timely visible and even audible feedback; · Elever information, all I want User machines received can be given and operated in accordance with their respective needs, such as operators can monitor and control, managers can modify operational mode and implementation of major decisions, financial and financial sectors for economic operations and balance of payment. In principle, embedded devices, in principle, embedded devices can be connected to the web server as long as the TCP / IP network protocol is converted to the web server. The principle is that there are many technologies that are implemented. Here are some of the schemes that have been implemented to peek.
High-grade MPU chip system Osicom has developed NET ARM system-level chip (SOC) to be the most intentional program. It is a 40MIPS ARM7 micro-core (Micrcore) using RISC technology, plus Ethernet; use the following network protocol: TCP (Transfer Control Protocol), UDP (User Data News Agreement), RARP (Reverse Address Conversion Agreement), ICMP (Internet Control Packet Agreement); there is also the following high-level software protocols on the Internet network: HTTP (Hyper Text Transfer Protocol), SMTP (Simple Mail Transfer Protocol), FTP (File Transfer Protocol); include PSOS RTOS (Real-time operating system, Integrated System operating system), and the like, the SOC. For example, the SOC embedded a printer can be online to become an online printer, so that any client on the Internet can use the respective browsers to use, monitor and control this printer on the web page. 32/64 bits of embedded systems It has sufficient ability and resources as the above SOC, and implemented effortlessness under the support of the operating system and functions. The principle of 8/16-bit embedded system is not different from the above, just take care of 8/16-bit system speeds and not enough memory, you must think of simplifying and maintaining the most basic things, ie embedded The device must change to the web server, be sure to add TCP / IP network protocol. Phar Lap Company Phar LAP puts the independent smart part and network part as much as possible to embedded devices, such as some predefined data transfer to the fat client, use embedded devices to access the DLL there of DLL from remote calls; The TCP / IP protocol is necessary for the Internet to transfer data on the Internet, to provide the minimum requirements TCP / IP stack and the most streamlined TCP / IP protocol. The Web server is minimized by highly optimized the code. The last MicroWeb server made by Phar Lap is 25kByte, plus network protocols less than 300kByte. The program is short means fast, and the ASIC implementation means that the silicon area is reduced, it is cheap. Agranat Systems Agranat System creates an EMWEB server with its own feature on the embedded device. Accessing real-time data in HTML text; add special tags to HTML, enabling dynamic data on the web page to interface; TCP / IP protocol in C language library and other important Internet High-level software standards (such as HTML, XML, RVSA, TCN, etc.) merged into the EMWEB server. Therefore, the EMWEB server name is the server, and the network protocol is implemented, which is functionally two. There are many unique measures inside the EMWEB server, and the overall capacity is reduced to 25kByte, but performance is also highly raised. For example, it built-in state machine, supports HTML, and multi-interfaces, multi-interfaces, and multi-user requests. Because it is independent of the operating system, there is no need for multitasking or multi-threaded support. Despite this, EMWEB is also provided with the convenience of customer applications, such as interfaces such as VxWork, PSOS, Chorus, Nucleus, etc. EMWEB uses a development platform for composite functions when developing. Standard web tools can be selected on the platform, such as Microsoft's FrontPage, Macromedia Dreamweaver, etc .; platforms also support compilation of C, Java, JavaScript, and file formats such as GIF, HTML.
Human-machine dialog is available in Windows or UNIX graphics interfaces. Because Kung Fu has more, I hope to cure Emweb to ASIC, and promote the home and industrial automation. Emware Emware faces the reality of 8/16-bit microcontrollers and takes another way. The server part of the local end is deliberately simplified to only the mark of the HTML, and the other server parts are all moved to the client side; the network protocol part will give up the long-term TCP / IP protocol for very lightweight network protocols, thus Reduce the name Emmicro of the device to a small 1kbyte byte. Moreover, Emmicro has two parts: EMTAG corresponds to the HTML mark, and the EMNET corresponds to the network protocol, which is also a functional two in one. Light Weight Network Agreement can support the construction of the net. If it is not with the Internet, it is an isolated network; for the Internet network, it is necessary to increase the gateway, and the interchange of the exotic network protocol is required. The gateway can be set separately, or combined with the specific conditions and the fat client, or others. This gateway name Emgateway. Emgateway's Internet is left with an interface with a web device of the hanging net. The typical use of the interface is to use a web page, which can work under any browser, flexibly adapted to the diverse environments of the global network. The interface can also be used in the user's application as needed. EMTAG in Emmicro maps the corresponding HTML tag to the object or JPEG / GIF object in Java Applets in the Internet side browser or gateway, which is EMOBJECTS. The HTML web page recognizes EMTAG and is replaced with a mapped object, which is manifested in the form of numbers, graphics, text, or sliding control handles, operation switches, buttons, LEDs. A device access service utility that is also installed on the gateway is also installed in the Gateway DAS (Device Access Service). It is identified, accessed, and monitors the WEB device of each hanging network, and the role of the starting scatter. The above set of technology is named embedded micro Internet Technology EMIT (Embedded Micro Internet Technology). The new progress has been said to use the browser to access, control, and display the web device of the Internet side from the Internet side using the browser. Can you have a more direct way without a browser? Enlightenment by PHAR LAP Company MicroWeb Server, use the data of JavaScript more direct method Java to handle and run other systems or devices, and the conditions should be interpreted by JavaScript in other systems or devices. The program will be on. In addition, from MicroWeb-separated data text may be directly loaded into standard applications such as Microsoft Excel, conveniently perform graphical analysis processing in the form of a spreadsheet. Extensible Markup Language, eXtensible Markup Language, has a more flexible application space. It will be a major reform of data transfer and formatting information methods on the Internet online. XML provides advanced standards for the submission method of information. It is both a language and a set of standardized data application rules. Different types of terminal devices can extract data from the same format information according to their own understanding, respective format information. Handling and use. In fact, the HTML format is originally a subset of SGML standard universal markers language formats. A STANDARD General Markup Language. The marker language is in hypertext, including textual tags to define the layout of the document, etc. so that the user is explained.
