说明：  一个EDMA操作EER设置的例程 该事件使能寄存器（EER/ EERH的）不能被直接 写入修改 它们。多个任务的情况下，这样做的目的是为了减轻软件的负担 试图同时修改这些寄存器。该事件使能设置寄存器
(Routine set by the a EDMA operating EER the event enable register (EER/EERH,) can not be written directly modify them. In the case of a plurality of tasks, the purpose of doing so is to reduce the burden on the software attempts to modify these registers simultaneously. The event enable set register)