说明：  PIC16F72定时器C程序，包含报警程序、显示子程序、AD转换初始化子程序、初始化子程序、按键等待程序、时钟显示程序、按键处理子程序
(PIC16F72 timer C program, including police procedures, display routines, AD converter initialization routine, the initialization subroutine, wait for the program button, the clock display program, key processing subroutine)