6. Connect 7447 decoder 4-pins to the first 4-pins in PORTC.
7. Use first 6-pins in PORTA as the enable/disable pins for the six 7-segments.
8. Stop Watch counting should start once the power is connected to the MCU.
9. Configure External Interrupt INT0 with falling edge. Connect a push button with the internal pull-up resistor. If a falling edge detected the Stop Watch time should be reset.
10. Configure External Interrupt INT1 with raising edge. Connect a push button with the external pull-down resistor. If a raising edge detected the Stop Watch time should be paused.
11. Configure External Interrupt INT2 with falling edge. Connect a push button with the internal pull-up resistor. If a falling edge detected the Stop Watch time should be resumed.
12. Check this video: https://youtu.be/yYCSIoMDszU
