1、实时时钟——DS1302

时钟量由单片机送LED数码管显示。LED数码管的使用方法见上文。参考程序1实现预置时间，由软件编程输入当前时间初值，运行程序后LED显示当前时间。参考程序2用按键实现（年、月、日）、（时、分、秒）这两种状态的切换。参考程序3实现按键校时，一个按键可进入或退出设置状态，进入设置状态后，一个键切换所需修改的位，两个键对数字进行加减修改，按键退出设置状态后即返回显示状态。

-A real-time clock- DS1302 clock amount sent by the microcontroller LED digital display. LED digital tube use, see above. Reference procedure to achieve a preset time, enter the current time from the initial software programming, run the program, the LED displays the current time. 2 Use the keys to achieve reference program (year, month, day), (hours, minutes, seconds) to switch the two states. Reference procedure 3 to achieve key school, a key to enter or exit the setting mode, enter setup mode, a button to switch the bits you want to modify, add or subtract two keys on the numeric modify button to exit the setup display status after return .