CAN按键收发显示

代码说明：

说明：  ?A、B两块开发板上电，按开发板A上的按键S1—S4，A板将通过CAN总线向B板发送按键数字信息，B板接收到该信息后通过数码管显示出A版相应的按键值。(A, B two development board power, press the development board A button s1-s4, A board will send key digital information through CAN bus to B board, B board received the information through the digital tube display A corresponding key value.)