说明：  此代码为基于BF533的外设DMA的实验，实验目的是了解外设DMA的使用，学习如何使用DMA模式实现ADSP-BF533 UART的通讯功能。里面有详细的原理说明
(This code for the BF533-based peripheral DMA experiments aimed at understanding the use of peripheral DMA, learning how to use the DMA mode for ADSP-BF533 UART communication function. There are detailed description of the principle)