电子闹钟；AT89S51，液晶驱动，利用K1～K4按键可对时钟进行对时当首次按下K1按键时，显示数码管第一位闪烁，继续按键时，下一位闪烁。当某一位闪烁时，按下K2按键可使闪烁位加一。在正常时钟显示方式下按下K2键时，转为年、月、日显示．按下K3键，可进入秒表状态，按下K4键可显示闹钟定时时间。-Electronic alarm clock　AT89S51, LCD driver, the use of K1 ~ K4 button on the clock from the time when the first press K1 key, the display LED blinks first, to continue button, the next flash. When a one is flashing, press the key K2 can blink bits plus one. In the normal clock display mode press the K2 key, into year, month, date display. Press K3 key to access the stopwatch state, press the button to display the alarm time K4 time.