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在嵌入式系统中,进行大批量的数据拷贝操作会占用很多CPU资源,降低了系统响应速度.直接存储器存取(DMA)是一种高效的I/O(输入输出)方式,具有传输速度快、CPU资源消耗低的特点.使用DMA方式进行数据传输可以占用较少的CPU资源,同时获得较快的系统的响应速度和数据拷贝速率.因此可以将DMA方式应用到需要许多数据拷贝的场合.本文分析了DMA的原理和嵌入式处理器中DMA控制器(DMAC)的特点,给出了DMA应用的一些实例和内存之间使用DMA方式进行数据拷贝的性能分析.
In embedded systems, large quantities of data copy operations take up a lot of CPU resources and reduce the system response speed.Direct memory access (DMA) is an efficient I / O (input and output) mode, with fast transfer speed , Low CPU resource consumption.Using DMA mode for data transmission can consume less CPU resources, at the same time get faster system response speed and data copy rate.Therefore, DMA mode can be applied to many data copy occasions. This paper analyzes the principle of DMA and the characteristics of DMA controller (DMAC) in embedded processor, and gives the performance analysis of some instances of DMA application and data copy using DMA between memory.