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

  this demo is based on the ht32f49041_sk board , in this demo, 
  shows how to use the can communication mode. every 1s transmit one message
  and the led4 blink, if receive a message, led2 blink(message id is 0x400) or led3
  blink(message id is not equal to 0x400).
  set-up
  - can tx      --->   pb9
  - can rx      --->   pb8


