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

  this demo is based on the ht32f49041_sk board, in this demo, pa6 pa7 pb0 pb1
  output waveform.
  c1dt overflow rate = tmr3 counter clock / c1dt_val = 366.2 hz
  c2dt overflow rate = tmr3 counter clock / c2dt_val = 732.4 hz
  c3dt overflow rate = tmr3 counter clock / c3dt_val = 1464.8 hz
  c4dt overflow rate = tmr3 counter clock / c4dt_val = 2929.6 hz
