Sometimes you may need simple countdown timer that is easily configurable and used. Take a look at 0-9999 seconds countdown timer that is based on PIC12F683 microcontroller and displays its current value on four seven segment LED displays.
In order to drive LED display there is a MAX7219 driver IC used. Timer can be set using couple if push buttons – one for incrementing time value and another for starting timer. Once timer reaches 0 value it sounds alarm using buzzer.