Seven Segment Simple Digital Clock Circuit - 16F628

Clock Schematic

This is a very simple clock circuit. The only IC used in this circuit was 16F628A pic micro-controller. This IC is very cheap and you can get it from any electronic spare parts shop. Four common cathode seven segment displays used to display time. We cannot get much accurate time using this. However, we can able to get reasonable accurate if we calibrate this circuit correctly. You can calibrate this clock by changing value of ‘Drift’. The ‘Drift’ variable is use to set calibration and it value should be in 0 to 255. In my code, value of ‘Drift’ is 198 and that is not the perfect value for it. You can get 0.5Hz frequency from RB7 if your ‘Drift’ value is correct.

Totally four buttons are used in this circuit and RESET button is optional. Min and Hour buttons used to update time and Mode button change the display mode. Two display modes are available. At the beginning, it will show hour and minutes on display. You can view seconds by pressing Mode button. Please replace NOT gate with NPN transistors such as BC547 and put 1k-10k resistors for base before connect with micro-controller.

MikroC used as programming language but you can easily convert it to MikroC pro or any other language. Because the code very simple. Micro-controller is running by its internal clock at 4MHz.The project files can be downloading from below with Source files, Proteus and Hex file.

Simple Clock