/**
  **************************************************************************
  * @file     readme.txt 
  * @version  v2.0.0
  * @date     2021-11-26
  * @brief    readme
  **************************************************************************
  */

  this demo is based on the at-start board, in this demo, show how to build
  a device of usb audio class protocol. the codec use wm8988
  the demo support:
  1. microphone and speaker 
  2. frequency 16k and 48k 
  3. bit width 16bit, 
  4. speaker feedback

