RAM、32 条 I/O 口线、2 个 16 位定时计数器、5 个中断源、一个全双
工串行口等。 按键电路设有两个按键：从上往下为 k1 和 k2 键。按
下 k1 键用于启动和暂停秒表；k2 键用于复位。另外还有一个单片机
的复位按键，此按键用于总复位，使单片机和 LED 数码管同时复位。
目录
一、设计任务和要求.......................................................................................................................3
（一）系统功能任务...............................................................................................................3
（二）系统设计要求...............................................................................................................3
二、方案设计与论证.......................................................................................................................3
三、硬件设计 ..................................................................................................................................4
（1）时钟电路.........................................................................................................................4
（2）按钮电路.........................................................................................................................5
（3）显示电路.........................................................................................................................6
（4）动态显示原理.................................................................................................................7
（5）80C51 中断的控制 .........................................................................................................7
（6）定时/计数器的控制 .......................................................................................................7
（7）单片机.............................................................................................................................8
（8）MAX7219.........................................................................................................................9
四、总原理图及元器件清单...........................................................................................................9
（1）总原理图.......................................................................................................................10
（2）元器件清单...................................................................................................................11
五、 源程序.......................................................................................................... ........... ..........11
六、结论与心得.............................................................................................................................15
