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Altera_Forum
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17 years ago

safe state machines

Hello, In the past, Altera recommended (in an older version of the Quartus handbook) to always explicitly specify the default state of state machines, to ensure that whenever a state machine ju...
Altera_Forum's avatar
Altera_Forum
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15 years ago

The one thing I believe, and just to be aware of, is that the safe encoding does not make your default statement get synthesized. Instead, it makes the state-machine go back to its initial state. Pretty much all the time those are in agreement, but if your default was something like a special error state, making the state-machine "safe" will not make it go to that mode. (I'm 90% sure of this but not completely).

Also, be sure you know why you want a safe state-machine. I've seen many people get worked up about this when they don't really need it, or when it doesn't provide the protection they think it does.