Incorporating a 4x4 Keypad in a Simple Digital Clock

Most simple digital clocks use a push button to increment time reading for time adjustment. It is often time consuming. This paper suggests adding a four-by-four keypad to adjust each single time digit. The required valid 4x4 keypad key set for each time digit is predefined in the circuit design. Pressing a prohibited key would neither generate any function nor affect the operation of the digital clock. The system prototype circuit design was based on Verilog hardware description language and implemented on an EVS6 Boardan FPGA lab board. With the proposed design, adjusting time on a digital clock is quick and easy.