l13 - Here is a summary of signals break the control down...

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6.111 Lecture # 13 FSM Hierarchy: We want to build a control system using multiple FSM’s Minor FSM’s are controlled (supervised) by a Major FSM All FSM’s use the same clock Minor FSM’s may be decomposed into multiple FSM’s themselves All FSM’s (major and minor) initialized by the same init signal Major FSM invokes minor FSM’s using a protocol that is much like a handshake: Wait until minor FSM is not busy Invoke minor FSM Wait while minor FSM does its thing and is not busy again Go on to the next thing… 1 It looks this way from the minor fsm On init this fsm is not busy It becomes busy when it is started It becomes not busy when it finishes and goes back to the init state Suppose we want to do two computations in parallel and then a third that depends on the two. And suppose this is part of a repetitive task, set off by a timer tick. 3 4 2
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Here is the data path from last time It might look like this: something is wrong if A,B and C are not ready at the timer tic 5 We could control this with one large FSM, but it seems reasonable to
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Unformatted text preview: Here is a summary of signals break the control down to several smaller (more easily developed and tested) FSMs, which must then be coordinated that go from control to data paths 7 8 6 The Main FSM (in this rendition) a: Controls the process and minor FSMs b. Multiplexes signals the multiple minor FSMs use Note that both minor FSMs control (at different times) elements of the data path. This is the Major FSM loop for the example of last time We do not have an error check here. A: probably do not want the trolley to hang up B: We are fairly sure we have time for the computations 9 Here is the minor FSM that controls the PI part of computation This is the minor fsm that controls the multiplication process. It controls another fsm which is a count zero to seven. No handshake is required for that counter because it is known to take only one clock cycle. The test variable CT is set when the counter reaches 7. The last bit is to rotate the answer back into place. 11 12 10 15 16 13 14...
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l13 - Here is a summary of signals break the control down...

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