The Design Of E1/Ethernet Adaptor Based On Embedded System

With the rapid development of information technology, transport networks, as the carrier of information, are going to combine each other when they become stronger. Many new technologies appear, which integrate the advantages of each transport networks, and provide service between them. This thesis introduces an E1/Ethernet adapter bases on embedded system. The adapter can make the best of plentiful E1 resource and integrate IP network's advantages such as the convenience of organizing network, the strong capability of controlling the terminal, and the service of providing transparent data transportation between PSTN and Ethernet. Based on a new type multifunctional E1/Ethernet adaptor, this thesis described the research and design of an embedded system. Related standards of E1 were introduced first, making a detailed discussion on the design and realization of E1 protect circuit,system clock recover and signal encode/decode circuits. The system, which uses FPGA as the pre-processor, realized such functions as E1 line and frame synchronization,CRC check,data and signalling pick-up/insert. Using ARM as CPU, the system realized Ethernet interface by embedding uClinux operation system. The middle part of the thesis discussed in detail the EMI&EMC existed in the circuit, and provided some means and experiences of debugging the system. The better part presented some improvements of design and realization of the system. There are three outstanding advantages of the system. Firstly, it is designed in modularization, which means the system power, E1 interface circuit, FPGA realization system root functions, and the system network function can be divided to design and realize; secondly, it is miniaturized and highly integrated, with which all functions can be achieved by an E1 interface motherboard and a childboard that integrates PPGA and ARM circuits; thirdly, it is a universal hardware platform, on which different modules can provide and realize different functions under different circumstances by modifying the software.