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Altera_Forum's avatar
Altera_Forum
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12 years ago

Finite state machine - doesnt change state second time & glitch

I have a fairly simple state machine that when in idle state, if txval is high should take the data from input port, put txbus flag to 1, then write it to FT245 chip and when writing is finished and ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
12 years ago

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But it has glitches on the txbus output, as Kaz mentioned. All signals should be synchronous - but txbus is asynchronous.

2 process state machines have fallen out of favour in recent times, for this reason (async outputs). The single process state machine is now favoured.

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I have implemented it as a single process FSM now, without reading your post. Code is simpler, shorter and easier to understand. Plus yes - output like txbus changes only on clk edges.