Deli COunter Display - April 2015
Project Overview
The aim of this project was to create a deli counter display that counts from zero to eighty. The design was to have a "Next" and a "Reset" push button inputs, which were used to go to the next number and reset the counter to zero. The counter had two outputs, one for each digit. When the count reached the number 80, it had to suspend. The ones-unit display had to use an MSI counter. The tens-unit display had to use four D flip-flops.
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MultiSim Circuit
PLD Circuit
PLD mode is different from design mode in a couple ways. The biggest difference is the use. Design mode is used to design a circuit, but then that circuit must be build separately. With PLD mode, the circuit is designed, then transferred over to the circuit board by plugging in two USB cords to the computer from the board, without having to build the whole thing again. Other differences include what parts are used to design the circuit, as the flipflops, AOI gates, power, ground, and "switches" have different names in PLD from design mode. To be able to use PLD mode with a board, the inputs and outputs must be assigned certain pins. That's what all the blue triangles are in the design above. They all the board to communicate with each of the inputs and outputs and know which inputs and outputs to use. Input and output connections are different, as the inputs are power, ground, switches, and the like, while outputs are the resulting action, such as the seven segment display or LEDs.
Bill of Materials
FInal Project COnclusion
SSI means small scale integration. MSI is medium scale integration. The difference is that SSI is the individual chips that are wired together by hand. MSI is a larger chip that contains multiple SSI chips inside of it. The limitation on using an MSI chip is that the count MUST start at zero; it cannot be wired to start from any other number, like SSI chips can be. Also, the MSI chips can only count up.
The Ripple Effect is the slight delay that occurs when using SSI chips that use the same clock by going through each other. This results in the last flip flop receiving the cue to flip later than the first flip flop did. This lag accumulates and results in a slight flicker in the display.
My circuit started by flipping the reset switch so the count would reset at the correct value (zero). The counter started and the signal traveled to the MSI chip. The MSI chip translated that signal as a value of 0001, and displayed a "1" on the seven-segment display. At the next rising edge of the clock, the MSI chip would register 0010, and display a "2" on the display. The count continued in numerical order until the NAND gate registered a 1010 signal, or a number ten. When the gate registered this, it signaled to the chip to restart the count at zero. Another NAND gate also monitored the count. This one served as the clock for the tens place. When it registered a 1001, or a number nine, the NAND gate would simulate the rising edge of the clock and the tens place would go up by one number, but the signal going through all four D flip flops to the seven-segment display. An inverter was connected to the Q output of the last D flip flop. Because the last flip flop was the most significant bit and an eight in binary, when there was a signal other than zero being outputted the display would be an eight. The suspend was supposed to occur at eighty, so the inverter would recognize the output and send a signal of "0" to the AND gate that the counter was also connected to. Because the AND gate only sends out a "1" signal when both the counter and the inverter send out signals of "1". But when the inverter switches to an output of "0" when the eight is registered, the count stops. Also included is a switch that resets both the ones and tens places to zero. It is attatched to the NAND gates that control when the counts restart at zero. An inverter is connected to the wire going to the tens place because the ones place reset on the upswing while the tens place reset on the down swing. Adding the inverter allowed the use of only a single switch.
For the actual circuit, however, it was a little bit different. Instead of having a button that would set things back to zero when pressed, I had to hold the button down for it to count. This was because the program wouldn't transfer over for some reason when the interactive switch was included.
Classmates circuits did look different from mine. Chase's, for example, only used MSI chips and didn't have SSI for the tens place. Jacob's had an actual switch that actually worked.
The Ripple Effect is the slight delay that occurs when using SSI chips that use the same clock by going through each other. This results in the last flip flop receiving the cue to flip later than the first flip flop did. This lag accumulates and results in a slight flicker in the display.
My circuit started by flipping the reset switch so the count would reset at the correct value (zero). The counter started and the signal traveled to the MSI chip. The MSI chip translated that signal as a value of 0001, and displayed a "1" on the seven-segment display. At the next rising edge of the clock, the MSI chip would register 0010, and display a "2" on the display. The count continued in numerical order until the NAND gate registered a 1010 signal, or a number ten. When the gate registered this, it signaled to the chip to restart the count at zero. Another NAND gate also monitored the count. This one served as the clock for the tens place. When it registered a 1001, or a number nine, the NAND gate would simulate the rising edge of the clock and the tens place would go up by one number, but the signal going through all four D flip flops to the seven-segment display. An inverter was connected to the Q output of the last D flip flop. Because the last flip flop was the most significant bit and an eight in binary, when there was a signal other than zero being outputted the display would be an eight. The suspend was supposed to occur at eighty, so the inverter would recognize the output and send a signal of "0" to the AND gate that the counter was also connected to. Because the AND gate only sends out a "1" signal when both the counter and the inverter send out signals of "1". But when the inverter switches to an output of "0" when the eight is registered, the count stops. Also included is a switch that resets both the ones and tens places to zero. It is attatched to the NAND gates that control when the counts restart at zero. An inverter is connected to the wire going to the tens place because the ones place reset on the upswing while the tens place reset on the down swing. Adding the inverter allowed the use of only a single switch.
For the actual circuit, however, it was a little bit different. Instead of having a button that would set things back to zero when pressed, I had to hold the button down for it to count. This was because the program wouldn't transfer over for some reason when the interactive switch was included.
Classmates circuits did look different from mine. Chase's, for example, only used MSI chips and didn't have SSI for the tens place. Jacob's had an actual switch that actually worked.