Large digital lab countdown timer

 The function of the Countdown Timer:

Count Down Mode:

1.Time is set by the "s"&"m" pins.Time setting is only effective in this mode and timer must be in the stop or reset stale.Tha maximum count time :99:59 minutes.

2.The time will reset to 00:00 if :s"&"m"are depressed simultaneously.

3.After the time has been set.Triggering the "START/STOP" pins will start the timer and the LCD displays"m""s"will begin to flash.

4.When the countdown timer reaches zero and the alarm signal ends,The LCD will retrned to preset time.If the alarm signal is stopped by the depressing "START/STOP",The LCD will returned to the preset time.

Count UP Mode :

1.The count-up timer will be triggering "START/STOP" start only when the chip has been reset and powered on without a set time .

2.The count-up timer has a cyclical count of 99:59 minutes after being started.

3.While the count-up timer is counting,depressing the any key will stop it.Another trigger of "START/STOP"will start the timer continuously counting.