Digital Alarm Clock Built Around PIC16F74 Microcontroller

The project utilizes a PIC microcontroller to design an alarm clock which comprises of two interlinked vero-board cards.

The real time clock is being read by the programmed microcontroller via I2C serial communication several times a second as the display is updated and no time keeping is being done. By means of a 1Hz output signal, the real time clock drives even the pulsing central pair of LEDs which the PIC also reads.

The 5V power regulator is held by the larger of the two circuit boards as well as the PIC16F74 display processor, the real time clock DS1307, 3V backup battery, and buzzer. Instead of using the crystal and separate capacitors, a 4MHz resonator with built-in load capacitors was used. The GND was connected to –ve terminal of the backup battery by adding another link.

The two functions performed by the PIC include comparing the time against the alarm settings to determine when it should go off and handling time, date, and alarm settings. All the settings are stored in the DS1307 and read at power-on-reset since the 16F74 has no EEPROM of its own although it has enough I/O.

Rest of the project