Sixty Second Timer
For this project, we had to use the concepts that we have learned about synchronous counter circuits to to design a 60 second timer that counts from 00 to 60. The design must have two control inputs and two output displays.
PLD Circuit
This circuit uses a 74LS163 synchronous counter for the ones digit and three J/K flip flops for the tens digits. A reset button is connected to the loads for both the ones and tens place. The circuit uses a multiplexer so the count can be displayed on the breadboard.
Final Project Conclusion
Synchronous circuits change state with every clock signal. Asynchronous circuits change states whenever the inputs change. Synchronous counters are faster and take more logic than the asynchronous counters. Another difference is that the synchronous counters don't have the ripple effect because of the delay in each of the flip-flop. The difference between 74LS163 and 74LS193 MSI logic gates are synchronous and asynchronous Load and Clear. The'163 is the only gate that shows the number entered into the Load input. Also, the '193 counts both up and down but the '163 only counts up. When the counter is on, the '163 counter counts up from 0 to 9 in the one's place. The SSI J/K Flip-Flop's control the ten's place and reads the binary on the rising edge of the clock. It count up starting also at 0 and end at 0110 or 5. This makes the display count from 00 to 59. It will repeat this count unless the reset switch is hit, then it will bring the count back to 00. This Reset is onetwo AND gates that are connected to the Load and Clear. When it is zero, the display turns to 00 until it is toggled back to power and the counting starts at from the beginning. The clock should be set to 1 Hz so that every second it count up. In the PLD, there are two seven segment displays named DEC_BCD_7. There are also pins throughout the design, that have specific jobs in the circuit. Then this can be transferred to the board The only two inputs are the Clock, which is pin number 14 and the Reset which is pin 48. My board look pretty much the same, compared to the rest of my classmates. Everyone used the same gates and chip to make the 60 second timer.