以太网是现有局域网采用的通用的通信协议标准.千兆以太网向下完全兼容10/100 Mbps以太网,并利用了原以太网标准所规定的全部技术规范.作为以太网技术的核心,千兆以太网MAC层协议是数据帧收发的基础,负责上层数据和物理层比特流的封装和解封,流量控制,校验检测等功能.针对航电系统应用中对通信带宽和数据实时性的要求,文中提出了基于DMA的双通道千兆以太网MAC方案.首先对缓冲区描述符存储结构进行描述,基于此种存储结构提出了基于DMA的双通道千兆以太网MAC架构设计,最后对发送、接收模块微结构进行了详细设计.在NCSim平台下对整个设计进行了仿真验证.结果表明GMII接口能够以10/100/1000 Mbps的速率实现半双工/全双工通信,满足设计要求.%Ethernet is the popular communication protocol standard implemented in existing LANs. Gigabit Ethernet is fully compatible with 10/100 Mbps Ethernet,and adopting all specifications of original Ethernet. As the key of Ethernet technique,gigabit Ethernet MAC is the base of frame data transmitting,it implements the assembling and disassembling framing between upper data and physical level,flow control,and CRC check so on. Aiming at the demands of high-bandwidth and real-time-transmission in avionics applications,a method of dual-channel gigabit Ethernet MAC based on DMA is put forward. First,an overview of buffer descriptor is described,based on which propose the system design of dual-channel gigabit Ethernet MAC based on DMA. Finally,the structure design of sending and receiving module is discussed. Through simulation of the whole design under NCSim platform,the results show that the GMII interface can work in Full Duplex/Half Duplex mode at 10/100/1000 Mbps respectively to meet the requirements.
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