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

  this demo is based on the at-start board  and at32-comm-ev, in this demo, 
  shows how to use the can filter funciton. the can tool transmit 6 specified 
  messages in total (3 extended-id messages and 3 standard-id messages), 
  when mcu receive one expect id message, test_result will add one, if test 
  success, only 4 filter messages will be received, the three leds will toggle.
  set-up
  - can tx      --->   pb9
  - can rx      --->   pb8

  for more detailed information. please refer to the application note document AN0095.
