该模块实现串口DMA发送中断接收，与系统或者外设通信，一发一答的方式，发送一帧数据，需等待对方应答，如果在规定时间内未等到ACK数据，发送端 会重发该数据，采用状态机制原理，对串口使用以及协议搭建很参考价值(The module DMA send serial interrupt receiving, and system or peripheral communication, one answer, send a fr a me of data, need to wait for the answer, if ACK did not wait until the data within the specified time, the sender will retransmit the data, using the state mechanism principle, build a reference value for the use of serial port and protocol)