基于FPGA的PCI接口DMA传输的设计与实现

Design and Realization of DMA Transfers in PCI Interface Based on FPGA

PCI总线是高速同步总线,支持单字段传输和突发传输,突发传输中,写一次地址,传输多个数据段。DMA技术是一种由DMA控制器控制的存储器与外部设备或存储器之间大数据量传输的方法,具有传输速度高,CPU额外开销小的优点。介绍了一种使用FPGA在32位PCI接口内实现DMA块模式传输的设计方法,硬件部分基于Xilinx Virtex-Ⅱ ProTM芯片,通过一个OPB-PCI总线桥实现了PowerPC与主机间的PCI接口通信,不仅实现了PCI的突发式传输,发挥了PCI总线的高性能,而且将CPU从繁杂的I/O事务中解放出来,解决了原有通信系统中采用中断方式传输的瓶颈,使得PCI接口卡与主机间传输效率得到明显改善。

PCI Bus is a kind of synchronous and high performance bus, supporting burst or single- cycle mode. A burst transfer is one consisting of a single address phase folk）wed by two or more data phases. Direct memory access （DMA） is a means of having a peripheral device control a processor＇s memory bus directly. DMA permits the peripheral to transfer data directly to or from memory without having each byte （or word） handled by the processor. Thus DMA enables more efficient use of interrupts, increases data throughput, and potentially reduces hardware costs by eliminating the need for peripheral - specific FIFO buffers. Introduces a design method of realizing block DMA transmission in 32 - bit PCI interface based on FPGA, with the choice of Xilinx Virtex- II ProTM, realizes data communication between the PowerPC and host by means of a OPB- PCI Bus bridge ,not only realizes the burst- mode transmission and embodies the superiority of the PCI bus, but also releases the CPU from the miscellaneous work of I/O ,solves the bottleneck of the original communication system, significantly improves the transmission efficiency between PCI interface card and host computer.