A digital clock is a type of clock that displays the time digitally, as opposed to an analog clock,where the time is indicated by the positions of rotating hands. It displays time in three numeric values - hour, minute and second. The digital clock is designed for a 24-hour count time. Theclock displays 6 digits: 2 digits for hours, 2 digits for minutes, and 2 digits for seconds. It runs from 00:00:00 to 23:59:59. Driven by a 32.768kHz clock source, the chip can either operate with an off-chip crystal oscillator or an external clock input. The second count increments its value by 1 at the rate of 1 Hz. When the second count overflows (reaches 59), the minute count is incremented by, when the minute count overflows (reaches 59), the hour count is incremented by 1.

A time-setting mode was implemented into the digital clock chip to allow the user to manually adjust the time. Both hours and minutes can be increased by applying positive-edge signals on the respective input pins labelled Advance Minutes and Advance Hours.Our digital clock implements all of the above functionalities. It displays the three numeric values on six 7-segment LEDs on the printed circuit board (PCB). It keeps track of the current time and computes the display outputs in the integrated circuit (IC).

The figure above shows the core part of the project. It uses off-chip crystal to provide a stable block resonance and inside the IC is where all the digital logic computations take place (boxed by dotted lines). This chip is a low-power high-performance digital clock fabricated with IBM 8RF 130nm CMOS technology and a supply voltage of 1.2V.