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Logic Networks/Seven Segment Displays

  1. Sep 23, 2010 #1
    1. The problem statement, all variables and given/known data
    Here's the problem:

    Design a logic network that can display the characters in “APPLE” on a sevensegment
    display unit. Write the truth table for the output functions C0-C6, minimize them
    by using Karnaugh Map, and implement using discrete logic gates.
    (Hints: Character “A” will be displayed if segments (C0, C1, C2, C4, C5, C6) of a 7-
    segment display are turned on and segment (C3) is turned off. Since only 4 characters
    will be displayed, input of 2 bits to encode them will be needed for the given design.)

    Now, where I get confused is when it says an input of 2 bits to encode them will be needed. I understand that technically only 2 bits are needed, but I do not understand how to implement it using only 2 instead of 4. I've been searching and thinking of different ways to do it but I am stumped.

    2. Relevant equations
    Not quite applicable

    3. The attempt at a solution
    With 2 bits to work with:
    00 = A
    01 = P
    10 = L
    11 = E
    Code (Text):

    A   B   C0  C1  C2  C3  C4  C5  C6
    0   0   1   1   1   0   1   1   1
    0   1   1   1   0   0   1   1   1
    1   0   0   0   0   1   1   1   0
    1   1   1   0   0   1   1   1   1
    But what is the point of using a K Map for this? I am almost sure this is where I am wrong but I have no idea what to do?

    Any help will be greatly appreciated! Thanks

    Attached Files:

    Last edited by a moderator: Sep 23, 2010
  2. jcsd
  3. Sep 23, 2010 #2


    User Avatar

    Staff: Mentor

    Welcome to the PF.

    Everything you've done looks correct. Now just do the 7 K-maps (or just write the 7 equations) that define the logic that drives the 7-segment displays. The same logic is repeated at each display, and drives the 7 segments based on that 2-bit input AB.

    BTW, I edited your post to insert Code tags around your table. This preserves the column alignment.
  4. Sep 24, 2010 #3
    Thanks a million berkeman, I think I got it all figured out!
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