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Unformatted text preview: • Apply the first four state assignment rules to determine the number of pairs of adjacent logic values that would result from each values that would result from each pair of states receiving adjacent codes. Record this information in the appropriate box. Applying the State Applying the State Assignment Rules Assignment Rules x 1 x 2 00 01 11 10 A B / 11 C / 00 B / 11 B / 11 B C / 01 F / 10 B / 10 B / 01 C B / 11 A / 00 B / 11 F / 11 F C / 11 F / 11 B / 00 H / 00 H B / 11 C / 00 B / 11 F / 11 NS / B I I I NS / z 1 z 2 III IV C Legend F H A B C F Applying the State Applying the State Assignment Rules Assignment Rules • To make the state assignment, use To make the state assignment, use a Karnaugh map whose variables correspond to the state variables f th f ti of the function. • Placing a state in a particular box of the map assigns that code to the state. • Assign codes to the states to in a th t i i th t t l way that maximizes the total number of adjacencies found in the mileage chart. Applying the State Applying the State Assignment Rules Assignment Rules 6 4 I B 6 4 I II 14 4 III IV C 6 0 3 10 Legend 16 19 C 16 19 2 8 2 4 F 3 9 1 2 3 4 5 2 5 9 2 4 2 H 9 3 2 9 2 3 1 7 9 1 9 7 8 4 8 2 2 A B C F y 2 y 3 y 2 y 3 00 01 11 10 00 01 11 10 y 1 y 1 1 1 Applying the State Applying the State Assignment Rules Assignment Rules • After making the assignment After making the assignment, calculate the number of additional Rule 5 adjacencies that result. • Repeat the last two steps to obtain several candidate state assignments. Choose the one with the greatest number of total adjacencies. If there is more than one implement each one and one, implement each one and select the one with the lowest cost. Applying the State Applying the State Assignment Rules Assignment Rules x 1 x 2 00 01 11 10 A B / 11 C / 00 B / 11 B / 11 B C / 01 F / 10 B / 10 B / 01 C B / 11 A / 00 B / 11 F / 11 F C / 11 F / 11 B / 00 H / 00 H B / 11 C / 00 B / 11 F / 11 NS / y 2 y 3 00 01 11 10 NS / z 1 z 2 00 01 11 10 y 1 H A 1 C B F Applying the State Applying the State Assignment Rules Assignment Rules • There are multiple state There are multiple state assignments that will produce the same numbers of adjacent pairs. H d h d How do we choose a good one? • Choose one that populates the maps with ones. • Choose one that populates the maps with zeros. • Obey the constraints of the flip flop. This actually creates another design tradeoff....
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 Summer '06
 JSThweatt
 Karnaugh map, Maurice Karnaugh, Rule Rule

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