| With the rapid development of telecom and internet network ,it is in the great demand to realize the intercommunication between telecom and internet network,which can make good use of the network resource,so how to interconnect the E1 and Ethernet transmission line is very importance.the E1/Ethernet adapter based on embedded network platform implement the data transmission between E1 and Ethernet transmission line ,and meet the practicality requirement. Based on a E1/Ethernet adapter, the researching and designing of an embedded system is described in this paper. Firstly,the paper introduce the embedded system,and give the system structure of the device.Then design method of the main chip(ARM processor and FPGA),the transplant of uClinux operating system is mentioned,and describe the hardware circuit design of system. In the devic FPGA is used as the interface to E1 transmission line. the E1 interface design with fpga is detailedly explaided, and all of the fuction module such as HDB3 code&decode,E1 line clock recovery,frame synchronization,CRC4 check,E1 frame organize,E1 data buffer,bus interface between FPGA and ARM processor is mentioned.Moreover ,this paper have described the hardware description language, FPGA based on the top-down design flow, the development instrument and the means of debugging. It also has discussed some questions and design experiences that were met in the FPGA's system development. Finally, this paper introduced the design of the high-speed circuit board and has carried on the detailed discussion to electromagnetism interfering and electromagnetic compatibility in the design process of the high-speed circuit PCB board. Regarding ARM network processor and extensive programmable logic device as the systematic hardware framework and regarding uClinux operating system as the systems soft ware platform, E1/Ethernet adapter is given full play to the function and characteristic of the systematic software and hardware platform in the design, and finishes the fulfillment of the system function. Function designing,hardware implementation and debugging of the system have been accomplished.Integrality and veracity of the hardware design scheme are demonstrated in the process of hardware module debugging and hardware-software joint debugging. |
