说明：  设计并实现一个4X8键盘接口控制器，含有时序产生电路、键盘扫描电路、弹跳消除电路、键盘译码电路、按键码存储电路、显示电路。要求：当按下某一键时，在数码管上显示该键对应的键值
(Design and implement a 4X8 keypad interface controller, with timing generator circuit, the keyboard scanning circuit, bounce elimination circuit, the keyboard decoder circuit, the key code memory circuit, display circuit. Requirements: When you press a key, the LED display key corresponding to the key)