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

  this demo is based on the ht32f49163_sk board, in this demo, 
  shows how to use spi access the w25q flash chip.
  the pins connection as follow:
  - spi2                     w25qxx
    pb12(cs)        <--->     cs pin
    pb13(sck)       <--->     clk pin
    pb14(miso)      <--->     di pin
    pb15(mosi)      <--->     do pin
