Every digital clock has a crystal inside it to keep track of time. This crystal is not only present in the clock but also present in all computing real-time systems. This crystal generates clock pulses, which is needed for timing calculations. Although there are some other ways to get clock pulses for higher accuracy and frequency, but the most preferred way is to use crystal to keep track of time. Here we will DS3231 RTC IC to build an Atmega16 based Digital Wall Clock. DS3231 RTC has a highly accurate crystal inside it, so no external Crystal oscillator is needed.
In this Digital Clock Project, ten common anode 7-segment displays of 0.8-inch are used to display time and date. Here seven segment displays are used to show hour, minute, date, month and year. Our PCB design also has options to display seconds and temperature, which can be displayed by adding more display units.
For this Atmega16 based wall clock project, we have designed two PCBs. One is for Control unit which is used to control all the operations of the project and second part is for displaying the time and date on seven segment displays. Display part contains five pairs of 0.8 inches seven segment display. So by assembling 5 pieces we have the complete Digital Clock. To multiplex 7-segment displays, Data line of the 5 PCBs will be connected to the same port of control unit and control line is connected different pin of the control unit.
Below are the top and bottom views of PCB layouts of one Display board which consists two seven segment displays:
Below are the top and bottom views of Control Unit PCBs