功能：读取DS1302时间，包括小时和分钟，并送时钟数码管显示

key1，实现循环切换小时十位、小时个位、分钟十位、分钟个位、退出设置等功能；当切换到对应位时，对应位闪烁！

key2: 修改对应的时间值， 实现加1功能，根据key1cnt的值，修改对应的位 ，如key1cnt=1，则修改小时十位，且每按1次，该位加1. ，

key3: 实现修改，将key2设置的小时分钟写入DS1302，修改完成后退出修改状态，即key1cnt=0.-Function: read DS1302 time, including hours and minutes, and send clock digital tube display



Key1, the realization of the cycle switch hours ten, an hour, ten minutes, a minute, exit settings and other functions　when the switch to the corresponding bit, the corresponding bit flashing!



Key2: modify the corresponding time value, achieve 1 functions, according to the value of key1cnt, modify the corresponding bit, such as key1cnt=1, then modify the hours ten, and each press 1 times, the bit plus 1,



Key3: implementation of the change, the key2 set the hour minutes to write DS1302, modify the completion of the withdrawal　the modified state, that is, key1cnt=0.