3 Variable Karnaugh Map tutorial

In this lesson we're going to look at an example of solving a 3-Variable Karnaugh Map.

The main thing to remember is that the Karnaugh Map will contain the same information that is in the truth table. What we have to do, is just to make sure that the information is transferred properly.

One of the most common mistakes when drawing the Karnaugh Map is the mis-labelling of the cells. Remember that to maintain the adjacencies, only one bit is allowed to change as you move from one cell to the other. So instead of the regular count that we're used to, 00, 01, 10, 11, the cells will be labelled 00, 01, 11, 10. Again, this is done to ensure that only one of the bits change as you more from one cell to any adjacent cell.

Once this is accomplished, all that is left to do is to transfer or "map" the outputs from the truth table to the Karnaugh Map.

When it comes to looping, or grouping the 1s, please remember the following rules:

  1. Loops must around term in a power of 2, eg: 1, 2, 4, 8, 16, etc.
  2. Make the loops or groups as big as you can for maximum simplification.
  3. Once all of the 1s are looped, you're done!
  4. Overlap is allowed, provided every loop or group has at least one "1" that is unique.
  5. There shouldn't be any 0s in any of the loops.
  6. Don't care states (x) may be included in loops or groups for the purpose of making bigger groups.
  7. There should be no loops containing only don't care states ... there must be at least one "1" in every group.

Please follow along with the video, and when you do, I recommend drawing the map out and doing the exercise that is in the video.

The practice problems will include some sample maps to complete ... please take advantage of the resource materials ... as with all things, practice is essential!

And, as usual, if you have any questions of comments on this particular lesson, please let me know!