The Challenge

Any decimal digit from zero through nine can be displayed by lighting the appropriate segments of a 7-segment display, as shown below in Figure 1:

THE SEVEN-SEGMENT DISPLAY

Figure 1: Segment definitions of a 7-segment display.

The desired decimal digit is expressed in binary-coded-decimal (BCD) format, and then used as an input to a logic network which controls the seven segments.
 

For this project, you will develop a multiple-output logic network that drives a 7-segment display, yielding all ten decimal digits. Here is how you will proceed:

Part 1:

1. The input variables will be the BCD representations of the decimal digits 0-9 (use switches 0-3 on your DE-2 board: SW0= LSB, SW3= MSB).

2. Using Karnaugh maps, determine the seven output functions for controlling each of the seven segments, in minimum SOP form. Using Don't Cares will greatly simplify your output functions.

3. Express the seven output functions in AND-OR form.

4. You will display the digit on the left 7-segment digit on your DE-2 board.  Refer to the DE-2 Manuals regarding how to enable a specific digit on this display.  Hint:   Applying a logic low level to a segment causes it to light up and applying a high level turns it off.

Design Constraints: Use 2-, 3-, or 4-input  gates, except that inverters may be used to invert input variables. A design with 20 or fewer total  gates ( AND and OR) is required (don't count inverters in your tally).  Your circuit schematic should show the actual gate-level diagram of  the  hardware circuit.

5.  Using Quartus-II, create the  schematic and simulate it with all possible 10 inputs.  Then implement this hardware on your DE-2 Board and test it, again with all 10 possible inputs.  You should also examine the display shows when you create illegal BCD digits, i.e. values of 10-15 on your switches.

6. Optional: Design and simulate another version of the network again using NOR gates.  NOT gates, used to invert the input signals, are always permissible.

7. Extend your work to display numbers from 0 to 99. The inputs will be two BCD digits, each representing a decimal digit  0-9 (use switches 0-3 on  DE-2 board: SW0= LSB, SW3= MSB for the less significant decimal digit and use switches 4-7 : SW4= LSB, SW7= MSB for the more significant decimal digit). Output is to be displayed on the  two leftmost 7-segment digits on your DE-2 board.

Part 2:               
                             Repeat Part 1 using 4:16 Decoder and OR gates.

REPORT

Prepare a memorandum which is addressed to the manager of the R&D group at Banana. Go to the Preparing the Memo link to review the general requirements for Banana Memos or to the What to Include and Grading Policy  link for the specific things to include in the Project #6 report.

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