Hardware Reference
In-Depth Information
Figure 1.12
Example of Mealy-to-Moore conversion (“ abc ” detector of i gure 1.3c).
This is shown in i gure 1.11c, where only state A was split because it is the only state
with multiple output values. Another example is presented in i gures 1.11d-f, follow-
ing the same procedure. The analysis of this example is left to the reader.
Just as a check, note in
i gure 1.11c that the outward transitions of states A
and
A
are alike and that the equal transitions go to the same state, so A
and A
can be
merged. Observe in i gure 1.11f that the pairs A
-A
and B
-B
also fuli ll the merging
requirements, so they too can be merged.
A i nal example is presented in i gure 1.12. In i gure 1.12a, the same Mealy machine
of i gure 1.3c is shown (just reorganized horizontally). Note that there are four possible
transitions into state A, of which the i rst three must produce y = '0' while the last
one must produce y = '1' (hence with two possible values for the output). On the other
hand, note that the transitions into states B and C must all produce a single output
value ( y = '0'). The resulting intermediate diagram, with Moore notation, is shown in
i gure 1.12b. Because only state A has more than one output value (two values), only
A needs to be decomposed (into two states), resulting in the Moore machine shown
in i gure 1.12c. The reader is invited to compare it against that presented earlier, in
i gure 1.3b.
1.9 Algorithmic State Machine Chart
An algorithmic state machine (ASM) chart is another way of representing a state
machine instead of using a state transition diagram. An ASM chart is a l owchart-like
diagram containing information equivalent to that of the state diagram but generally
in a more textual, algorithm-like form.
Search WWH ::




Custom Search