说明：  8255C口接逻辑电平开关K0~K7，A口接LED显示电路L0~L7，编程从8225C口输入数据，再从A口输出
(8255 C port logic level switch K0 ~ K7, A port LED display circuit L0 ~ L7, programming input the 8225C port, and then the A port output)