Network Interfaces In Embedded Systems Research And Development

Along with development and popularization of computer technology and network technology, pocket embedded equipment with single-chip computer have already applied extensively in industrial automation, official automation and building automation etc.To realize the long-distance data-collected, control and so on, the network has become a trend of the development of new generation embedded system. It has important realistic significance and economic value to research the connection of embedded system and Internet.A method, which achieved a network monitoring system of wireless temperature sensor with network card chip RTL8019AS of ISA of Realtek Inc and 8-bit single-chip computer AT89C51 of Atmel Inc, is given in the paper.Temperature sensor of AD7416 of Analog Devices Inc and wireless transceiver of nRF403 of NORDIC Inc are also used in the system .The interface of singlechip,temperature sensor and wireless transceiver and the interface of Ethernet network are designed in hardware , the driver of network card control and TCP/IP protocol is designed in software.The paper includes the introduction of characteristic of AT89C51 microcomputer, the reason of choosing network card chip RTL8019AS, giving the circuit of hardware interface and the explanation of mostly periphery parts. The design of the driver of network card is introduced in the paper. The interior structure of network card chip, the main pins, the frame format of Ethernet, the principle of receive&send data package, the operation of DMA are described in detail and the flow chart ofprogram is also given out. TCP/IP is an ensemble of many protocols. Considering the limited resource of 8-bit singlechipcomputer, some functions are reduced to alow single-chip computer to go internet buTCP/IP protocol and package format are explained in particular. The work flow of system and the flow chart of each TCP/IP module are given out, too. The connection of single-chip computer and Internet is research in this paper and the resultshows that it is feasible. It can provide data for long-distance data-collected, diagnosis, software upgrade, etc. It can be turn into reality Key.