CSCI 162 Spring 2018: 7 Segment Display Circuit Lab


For this lab, you will use the Logic Gate Simulator available from the Applications menu → Education → Logisim. Use Logisim to program a 7-segment display.
  1. Write (on paper) the truth-table entries for all the integers from 0 to 9. The inputs are (most significant to least significant)i3, i2, i1, i0, and the outputs are in this order:
    middle, topleft, top, topright, bottomleft, bottom, bottomright. You can do this collectively, with your neighbour, or by yourself. Make sure you understand how these boolean functions were arrived at. If you like, you can put a "don't care" value (X, in logisim) for the bottom of a "9" and for the top of a "6". (Let me know which one logisim decides is the best option to minimize the circuit.)
  2. Select Project from the top menu in Logisim. Enter inputs i2, i1, i0.
    Enter outputs m, tl, t, tr, bl, b, br.
    Enter the entries from your truth table. Enter (or leave it as the default) "X" for the don't care values that are at the bottom of the table. It is handy if the columns are in the order given above.
  3. Click on Minimized. Check out the Karnaugh map that Logisim has found for m, and for tl, and for tr (scroll through the outputs to see the K-maps). < Click Build Circuit.
  4. Select Input/Output: Seven Segment Display. Connect to pins on top, from left to right, the outputs m, tl, t, tr. Connect to pins on bottom, from left to right, the outputs bl, b, br.
  5. Test all settings:
    0000 = "0"
    0001 = "1"
    0010 = "2"
    0011 = "3"
    0100 = "4"
    0101 = "5"
    0110 = "6"
    0111 = "7"
    1000 = "8"
    1001 = "9"
  6. What gets displayed if the inputs are 1101, or 1011?