1、The Design of Embedded MCU Network Measure and Control System GAO Guanwang, WANG Yanpeng, SHA Zhanyou College of Information Science and Engineering,Hebei University of Science and Technology, ,Shijiazhuang Hebei, China Abstract This paper introduces a type of embedded MCU network measure and contro
2、l system based on Ethernet, which adopts high speed MCU with kernel of 8052. Through controlling the special chip for Ethernet, the system realized the function of TCP/IP protocol. Since the system can be used as a independent system, any computer on the net can control the system or transmit order
3、and data to the system through standard TCP/IP protocol. Equipped the system by digital temperature sensor, it can be used to measure industry field temperature and transmit the results to computer through network, and then get temperature curve. And its measure and control range are all -10125 ,the
4、 accuracy is 1 , the resolution reaches 0.1 . This system have many advantages such as simple structure,better universal, communicating through network, flexible usage, low cost etc. It can be adapted by various of intelligent sensor and has better extend ability. It can be used in the fields of rem
5、ote data acquisition, remote measurement and control and so on. Keywords: Embedded MCU Network Measure and Control System； Ethernet； System parameter； Digital Temperature Sensor. 1.Introduction The development history of the measure and control system experienced six phases in the following. (1)The
6、traditional control system consists of MCU, PC or IPC. (2) The measurement and control system based on PC bus. (3) Distributed Control System (DCS). (4) DCS system based on LAN. (5) HART bus which is developed by the 2-wire 4mA 20mA standard signal, and is a kind of fieldbus used between the intelli
7、gent field equipment and automatic control equipment. (6) Since 90s of the 20th century, with the rapid development of the Internet, it becomes possible that more quickly, more convenient and more economical gaining and exchanging information. So measurement and control system can become the client
8、of the global network. At present, the remote control system based on internet is driving the development of measurement and control technology, and has been applied in monitor fields of the nuclear power station, the oil transport pipeline, the power networks run and robot. The remote control syste
9、m based on internet has advantage of the quick information transfer, strong interactivity and low cost, while it can achieve data sharing. The existing network control equipment use mostly MODEM chip, with the PPP protocol dialing to the internet or special network by telephone network. Although thi
10、s method can realize the network control and data transmission, it depends on the telephone, make its use cost increase significantly. Additionally, transmission speed is no more than several hundreds kbps (usually only a few tens kbps or lower) because of the limit of telephone network, and it is n
11、ot adequate for the needs of large quantities of data transmission. Therefore, the network measurement and control technology based on Ethernet get more and more important. The ethernet is a widely used LAN standard, which can be defined by IEEE-802.3 standard, and it can support 10Mbps, 100Mbps, or
12、 1000Mbps bandwidth, often with twisted-pair cable or fiber as the transmission medium. Its characteristic is the low price, mature technology, flexible application. 2.Design Scheme of Edesign Plandesign Plandesign Plandesign Plandesign Planmbedded Microcontroller Network System It is a type of embe
13、dded MCU measure and control system based on Ethernet network system, using a microprocessor with 8052 as kernel. It realized common ARP, IP, ICMP, TCP and UDP protocol part function of TCP/IP on Ethernet by controlling RTL8019AS which is a special Ethernet chip. It can be used as an independent sys
14、tem on Ethernet network. Any computer on Ethernet can visit the system via the standard TCP/IP protocol, transport control commands or data among them. The system function has the following characteristics: (1) the simple structure； (2) with low cost, it is convenient to apply in many nodes； (3) str
15、ong adaptation can be used with various equipment； (4)it can communicate through the Internet. This system used serial interface for data acquisition, it can adapt all kinds of intelligent sensor and has strong ability of expansion, and can be widely used in remote data acquisition, remote control,
16、etc. The circuit diagram and the system program flowchart of embedded microcontroller network system are respectively shown in figure 1, figure 2 In order to realize the standard TCP/IP protocol with microcontroller, Winbond Company W78E58 MCU production is used as main control chip in the circuit d
17、esign. The W78E58 MCU can meet the following three conditions: the first, it is compatible with MCS - 51 series microcontroller, the second, the internal program memory is 32KB, and it is enough to write into a large program, the third, fast clock frequency can reach the 40MHz level. Figure 1. circu
18、it block diagram of embedded C network system The W78E58 as the center, along with the direction of data transmission, it can constitute two main function modules: one is data acquisition channel, which is connected the W78E58 serial input/output port via MAX232 interface chip, the Two is finishing
19、read and write operations or control to Ethernet interface chip and 32KB external RAM (62256) via W78E58 P0 port and P2 port. So sensors (or controller) data or control signal come from the network was first Ethernet chip received, and then sent to the W78E58 MCU for data processing , then transport
20、 to 89C51 MCU from the serial port, the 89C51 package the data into standard TCP/IP packets, then send to remote host. To adapt the network system to different sensors and web host, the syetem connected with a 2Kbit external Flash memory AT24C02 in addition, which was used to store the system parameters such as IP address, port, serial port setting and so on.
