See Also

When designing state machines in AHDL, you can either assign state bits and state values yourself, or allow the Compiler to perform this process.

To allow the Compiler to make automatic state assignments, draw a state diagram and construct a next-state table. The Compiler then performs the following functions automatically:

• Assigns bits, selecting either a T or D flipflop (TFF or DFF) for each bit


• Assigns state values


• Applies sophisticated logic synthesis techniques to derive the excitation equations

The Compiler uses advanced proprietary heuristic algorithms to make automatic state assignments that minimize the logic resources required to implement the state machine.

To specify a state machine in AHDL, you must include the following items in the Text Design File (.tdf):

• State Machine Declaration (Variable Section)


• Boolean control equations (Logic Section)


• State transitions in Truth Table Statements or Case Statements (Logic Section)

The following topics provide information on creating state machines:

• Implementing State Machines


• Setting Clock, Reset & Enable Signals


• Assigning State Machine Bits & Values


• Implementing State Machines with Synchronous Outputs


• Implementing State Machines with Asynchronous Outputs


• Recovering from Illegal States

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