is there any systematic way of trasforming an ASM chart to a sequential circuit immediately? I mean, given that the 'State Block' can be represented by a D flip-flop; 'Decision Block' is equivalent to two AND gates and so on.
I tried mapping these elements directly but I don't know how to do the conections properly. I usually draw impossible arrangements like this (this is just a part of a sequence detector):
Best Answer
Yes, the one hot method.
For a state diagram of N states, use N d-type flipflops and a code that has N - 1 zeroes and a single 1.
When you are in S0 then the S0 flipflop has a '1' in it. It is hot.
This method has the cost of needing one flipflop per state but does allow design by inspection rather than needing to draw up lots of tables. The method has other advantages so don't knock it! It suits register rich devices (fpga), has sparse logic which is easier to place and route and may actually be a lower power solution.
Using the state diagram examine the arrowheads entering each state. Write down a logic term for each arrowhead and OR them together.
Nb you must ensure the machine powers up to an initial state (000...1) this might mean using the preset pin of the first flipflop and the clear pin of all the others. (or you can add a reset term to the first equation.)
Best regards Ian Mccrum
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