/**
  **************************************************************************
  * @file     readme.txt
  * @brief    readme
  **************************************************************************
  */

  this demo is based on the at-start board, in this demo, shows in fullduplex
  mode how to use dma transfer data.
  the pins connection as follow:
  - i2s2 master                   i2s3 slaver
    pd0(ws)             <--->     pa4 (ws)
    pd1(sck)            <--->     pc10(sck)
    pc2(ext_sd) rx      <--->     pc11(ext_sd) tx
    pd4(sd) tx          <--->     pc12(sd) rx

  for more detailed information. please refer to the application note document AN0102.

