Ds1302 实现

1)　　显示分、秒、月、日、年；

2)　　可自由调整分、秒、月、日、年；

3)　　分秒作一页显示，月日作一页显示，年作一页显示；

4)　　上电后，时钟运行，显示设置的初始分秒值并开始正常运行，此情况下，按K3，则显示月日，松手则跳回分秒显示；按K4，则显示年，松手则跳回分秒。K1为设置键，按一次进入年的设置，2次进入月的设置，3次进入日的设置，4次进入月的设置，5次进入日的设置，6次回到年的设置。在设置环境下，K3和K4充当+/-键，在设置环境下，每次切换设置项，都会将当前设置的值实时存入寄存器，即切换设置项时自动保存调整后的值。K2为确认键，用于从设置环境退出，回到分秒显示。

-Ds1302 achieve 1) show minutes, seconds, month, day, year　2) can be freely adjusted points, second, month, day, year　3) every minute for a month for a show, and years as a display　4) electric clock running, set the initial minutes and seconds and begin normal operation, in this case, press K3, Month Day, let go then jump back to the minutes and seconds　K4, display years let go then jump back to the minutes and seconds. K1 to set key, press once to enter the year is set, 2 times a month set, three times to enter the date set, four times to enter the month setting, five times to enter the date set, return to the setting of the year six times. Set the environment, K3 and K4 act as+ /- keys to set the environment, each switch setting item, the current set of values ​ ​ stored in the registers in real time, that is, after the switch setting items saved automatically adjusted value. Enter key, K2 is used to set the environment to exit back to the minutes and seconds display.