Karnaugh Maps

Karnaugh Maps §

• A Karnaugh map provides a pictorial method of grouping together expressions with common factors and therefore eliminating unwanted variables and minimising terms

  • K-maps must use Gray code, meaning each sequence only changes by a single bit, unlike traditional binary sequence

• Step 1

  • Look at the output of the truth table and highlight all the times the output is TRUE (1)
    • If there are two outputs, you need two K-maps
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• Step 2

  • Place a 1 in the map for each row in the truth table that resulted in a 1
    • You should always fill blank spaces with 0s
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• Step 3

  • Place every 1 into the largest power of 2 (1,2,4,8,16)
    • The larger the groups the better
    • The fewer the groups the better
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• Step 4

  • For each group, record only the inputs that do not cancel (i.e. which input is consistent)
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• K-map Sources

  • K-maps can be drawn from truth tables or an expression
    • From an expression:
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  • Expressions that negate multiple terms

• Grouping

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