DELI COUNTER
Project Overview
In this project my goal was to design a digital circuit that would count up from 00 to 80 then stop and reset, like a deli counter display. This design used both D Flip - Flop chips and the 74LS93 MSI counter to control each circuit and have them work together on the same clock.
PLD Mode vs Design mode
Design mode is used as the “test or creative mode” it is used to design simulations of the circuit before uploading the code to the bread board. The inputs are connected to switches and outputs are connected to LEDs or displays. The PLD mode is use to upload the code to the board. The inputs and output are connected to certain pins of the chip, on the board the pins are connected to each element. When you wire the board the code will work in real time when the board switches are toggled and the lights in the board will display.
Conclusion
SSI or small scale integration is the use of basic AOI logic chips, such as and, or, and inverter chips, for gates less than 10. MSI or medium scale integration are chips greater than 10 but less than 100. I used the MSI 74LS93N chip to count the "ones place" from 0-9, by loading a 0 and detecting a 10, the only limitations of this chip are that is can only count up from zero. I used D flip-flop chips to count the "tens place" up from 0 - 8, loading 0 and detecting 9. In order to get my two circuits to count together in unison I needed to wire them to the run on the same clock. When you start the simulation the circuits begins to count when the ones place reaching 9, then the tens place increased by 1. However, the circuits kept counting up until the simulation was stopped, it did not stop at 80, or rest to 00. First I created a reset switch by connecting my 74LS93N circuit to the switch, by adding another AND chip to the flip flop circuit I was able to connect both circuit outputs the the switch so they could be reset together on the same count. The next step was to stop the circuit at 80, however my kept counting to 89. In order to do this I created a pause or suspend switch and attached it to the tens place, flip flop circuit. When the circuit/tens place reached 8 the MSB flip flop would turn on, this would signal the suspend count and reset both circuits, once detected with the inverter chip, resting both displays to 00. My circuit does experience the "ripple effect", flickering of the display due to the delay of the signal. My classmates designs do differ from my own, there are multiple ways we could create this circuit, like switching which "place" the MSI chip controls, however we did all have to follow the constrains of counting up from 00 to 80 controlled by 1 clock and reset.