overview
In this project we had to design a digital 60 second timer that counts from 0-59 and then resets back to 0 ad continues to count. It also must have a button that makes it go to 0 until you switch it back on then it counts 0-59 again. The ones digit is controlled by a synchronous counter using a 163 that counts from 0-9 every time the tens digit goes up 1. The tens digit is controlled by a synchronous counter using j/k flip flops.
PLD circuit
Unlike the DMV counter this project didn't suspend at its limit, instead it resets back to 0 and continues to count. This also counted from 0-60 instead of 0-80. It also uses j/k flip flops and a synchronous 163 MSI counter.
Conclusion
Asynchronous counters are not synched to the clock. Only the first flip flop is clocked by an external clock. Asynchronous counters are slower then synchronous, and they are called ripple counters. Synchronous counters flip flops are all clocked by the same external clock. They are also faster than asynchronous counters. There is no ripple effect but they require more logic. 163 counters are only up counter and can have any start number. It also ends with the detected number. The 193 can be up or down and can have any start number. It also stops one before the detected number. The first thing I did is look at my DMV project and used the same output circuit to display it onto the display. It has to count from 0-59 and then reset back to 0 and continues to count. It also must have a button that makes it go to 0 until you switch it back on then it counts 0-59 again. The ones digit is controlled by a synchronous counter using a 163 that counts from 0-9 every time the tens digit goes up 1. The tens digit is controlled by a synchronous counter using j/k flip flops. So I made a 3 input nand gate that detects a 6 and connected it to clear so it will reset once it reaches 59 because it stops one before the detected number. There is also a button or switch input connected to clear so you can reset it to 0. The j/k flip flops must count 0-5 then reset. To do this you only need 3 flip flops and you need to detect a 6 (110 so it only goes up to 59. The 163 that counts from 0-9 it needs to detect a 9 (1001) because it stops on the detected number. To breadboard it you have to connect the outputs to a-g depending on what order you outputs are. You need an input switch connected to the assigned pin so you can reset it back to 0. You also need a clock input so it actually counts, so you could use elvis digout for the clock when you breadboard. There were not many different circuits through the class unless they counted all the way to 60, then they had to add more logic to get it to do that.