/**
  **************************************************************************
  * @file     readme.txt 
  * @version  v2.0.5
  * @date     2022-05-20
  * @brief    readme
  **************************************************************************
  */

  this demo is based on the at-start board, in this demo, shows how to retarget
  the c library printf function to the usart. this implementation output the printf
  message on the hyperterminal using usart1. using pa9 to transmit data(printf).

  for more detailed information. please refer to the application note document AN0099.

