Project Overview
For this project, we were tasked to build a counter using two seven-segment displays for the DMV that would count from 0 until 80 and pause itself. Another requirement for this circuit was that it needed to be able to be cleared at any time. One of the circuits was created to count from 0 - 9, and the other circuit was just supposed to count from 0 - 8. The 0-9 circuit is set up so when it reaches nine, the counter resets at 0, but adds a value to the 0 - 8 counter. Eventually, after the 0-9 counter resets for the 80th time and sets the other counters display to an 8, the counter is paused and is able to be reset by flicking a switch.
Multisim and PLD Circuits
Bill of Materials
Conclusion
Overall, I have learned a lot about circuits, troubleshooting, and patience from this project. First off, I was able to finally recognize the difference between SSI and MSI circuits. SSI stands for Small Scale Integration, which would be something such as a flip-flop, counter, etc. MSI stands for Medium Scale Integration, which would be something such as a logic gate that contains multiple flip-flops. The circuit I created is not able to become a down counter, and its not possible to change the lower limit, so the display will always start off at 0. This circuit is asynchronous, meaning that all the flip-flops aren't connected to the same clock, so because of this there is a slight delay within the circuit creating whats called the "ripple effect". My ones display counter was controlled by an asynchronous counter designed with a 74LS93 (MSI). Using NAND gates and inverters, I made it so when a 10 was detected on the ones counter, it would send a clock signal to the tens counter, so only a nine was displayed before the ones counter reset to zero. My tens display and counter was controlled by an asynchronous counter designed with 4 flip-flops. I made the circuit stop itself once it hit 80 by implementing a pause function when the tens-unit display detected a 9. I believe all of my classmates completed their circuits with the same ideas as I did, but not everybody was restricted to making this circuit in one form.