60 Second Timer
Project Overview
PLD
This project is similar and different to previous projects we have done before because we have used asynchronous counters in our circuits before. For example, the last project we did was the Deli Counter project, it involved asynchronous counters controlling a counter up until 80. The two circuits were wired together on the same clock in order to count in unison, just like this project, we also implemented a restart switch in both projects so our displays would reset to 00 when the switch was clicked. However the 60 timer was a lapping timer so we did not need a pause switch because once it hit 59 it would lap back to 00. Also, this project incorporated a synchronous counter, 163' which was a new component for us, and detects differently than other counters.
Conclusion
Synchronous and asynchronous were both used in my design on the sixty second timer. Asynchronous counters have preset and clear which are not dependent on clock. They are effected by the ripple effect because the signal to the display is delayed. Synchronous counters are clocked by the same clock, and therefore are faster than asynchronous counters, and do not suffer from the ripple effects. However, synchronous counters require more logic than the asynchronous counters. There are two different type of synchronous counters we have learned so far, 163' and 193' in this project we used 163'. 163' is a 4 bit synchronous up counter, with a pre-loadable start count, that have synchronous preset and clear. This counter will detect the number that you want to see on the display!! However, the 193' 4 bit synchronous counter will count both up an down and it does also have a pre-loadable start count, but has an asynchronous load and clear, this counter detects the number above the one you want to see on the display.
I started creating my 60 second timer circuits by using previous circuits we have worked on in class. We were instructed to use JK asynchronous counters for the 10s place, that would count from 0-5. Then to use the 74LS193 synchronous counter for the ones place counting from 0-9. We also used 2 '48-To-Seven-Segment display drives 2 seven-segment-display common cathodes to display my results of each circuit, I had to make sure the drivers would correctly transfer the circuits output to the correct display segment. Once I had loaded these two previous circuits I needed to alter their detection's. For the JK flip flop I added a 3 input NAND gate and connect the input to detect a 6 so it would show a 5, because this counter does not show the number it detects. However, I was able to detect a 9 for the 74LS193 because it is the special case. Then I had to wire my two circuits together, I wired the output of my 74LS193 circuit to the clock on my flip flop circuit so they ran in unison. This is why I used an inverter so that the 10's place would change on the falling edge of the ones, after the 9 was shown. After, I have clocked my circuit together I need to create a reset switch to 00. I added an AND gate and connected it to the input of the flip flops output so when pressed it would reset to 0, resetting the ones place as well because they are clocked together.
My classmates designs do differ from my own, there are multiple ways we could create this circuit, like usinh different types of AOI logic, however we did all have to follow the constrains of counting up from 00 to 59 controlled by 1 clock and reset, using JK asynchronous counters and 74LS193 synchronous counters with 2 '48-To-Seven-Segment display drives and 2 seven-segment-display common cathodes.
I started creating my 60 second timer circuits by using previous circuits we have worked on in class. We were instructed to use JK asynchronous counters for the 10s place, that would count from 0-5. Then to use the 74LS193 synchronous counter for the ones place counting from 0-9. We also used 2 '48-To-Seven-Segment display drives 2 seven-segment-display common cathodes to display my results of each circuit, I had to make sure the drivers would correctly transfer the circuits output to the correct display segment. Once I had loaded these two previous circuits I needed to alter their detection's. For the JK flip flop I added a 3 input NAND gate and connect the input to detect a 6 so it would show a 5, because this counter does not show the number it detects. However, I was able to detect a 9 for the 74LS193 because it is the special case. Then I had to wire my two circuits together, I wired the output of my 74LS193 circuit to the clock on my flip flop circuit so they ran in unison. This is why I used an inverter so that the 10's place would change on the falling edge of the ones, after the 9 was shown. After, I have clocked my circuit together I need to create a reset switch to 00. I added an AND gate and connected it to the input of the flip flops output so when pressed it would reset to 0, resetting the ones place as well because they are clocked together.
My classmates designs do differ from my own, there are multiple ways we could create this circuit, like usinh different types of AOI logic, however we did all have to follow the constrains of counting up from 00 to 59 controlled by 1 clock and reset, using JK asynchronous counters and 74LS193 synchronous counters with 2 '48-To-Seven-Segment display drives and 2 seven-segment-display common cathodes.