Which FSM is better for designing in Verilog?

[kunal1514]

While desiging in verilog. Which fsm is best "Mealy" or "Moore" fsm and why?

 

[lythanhthuan]

why is mealy fsm faster

Independ of your using.

 

[s0shinde]

melay and moore machines

Moore over Mealy
In Mealy machine, output depends on the input. So any glitchy input will be propogated to the output. On the other hand, in more state machine output depends on the state only. So no glitches in the output.
Mealy over Moore
Moore statemachine requires one flipflop(denotes one extra state) more than Mealy. So there will always be 1 clock latency in Moore over Mealy.

So its a trade-off. You as a designer has to decide on the type of state machine to use.

 

[vinod_g]

melay and moore state machines

Mainly if u generating any control signals u should not get any glitches in that case it is better to use moore than mealy

 

[uditkumar1983]

synchronous moore fsm

Moore statemachine requires gives output at the clock edge but in mealy machine o/p comes at that time when condition is satisfied means one clock cycle delay occurs in moore machine.

State machine is preferrence also depend on the condition that u r designing for control path or Data path.

 

[caplash_vlsi]

mealy moore trade off

moore is more preferred to meally because its output is more synchronous to clk and thus does nt produce glitches......

 

[subramanyam]

meelay and moore state machines

moore takes atleast 1 clock cycle more than mealy.But in mealy , the output comb logic may produce glitches.

any design can be broken into ,
1)data path .
2)control path.

for designing data path u can choose mealy as is faster.
for designing control path u can choose moore as is glitch free so is reliable.

 

[davyzhu]

fsm of alu controller

Hi subramanyam,

You said "for designing data path u can choose mealy as is faster."

We know that all digital system can be splitted into "control path" "data path". And "control path" is used to control "data path".

But when to implement "data path" with FSM? Who can give out a simple example?

Best regards,
Davy

 

[salma ali bakr]

alu controller fsm mealy

well, moore is for control path and mealy for data path
since in mealy you can have the output of the current state right after you provide an input to it(which is from the moore machine), u won't need to wait for the next clock cycle to get it
this is to enable you to find the next state in the moore machine
and thus the next control commands to be used

u can have a whole system represented as an FSM with actions
which means u have certain conditions for the input, if they are satisfied, then the output is so and so(on the transitions for mealy)
and then this machine is translated into an operative part and a control part

but of course u can have a pure FSM just for an operative part
no specific example i have now to clarify but it's found

 

[adityakant]

fsm design-moors-melay

it depends on the implementation of the circuit. If delay is not required ,go for mealy else moore..

thanks

 

[angadir]

mealy moore state machine dont mix

Can anyone suggest me some book which explains u how to design FSMs in detail?

Thanks

 

[ray123]

control path fsm

it depends on the implementation of the circuit. If delay is not required ,go for mealy else moore..

correct, Moore and Mealy are often discussed in the textbook.
when you do design, you don't think much about Moore and Mealy.

Can anyone suggest me some book which explains u how to design FSMs in detail?

Please do a search in this forum, you will find many digital design textbooks talking about FSM.

 

[anmolvlsi13]

melay and moore machine examples

Mealy is Transition based
Moore is Stae based.

Anmol

 

[nmurthy]

designing fsms

hi


Refer to the following link for more info on melay and moore machine

https://en.wikipedia.org/wiki/Finite_state_machine


hope it helped you

 

[babaship]

melay fsm design

one pdf may be useful

 

[blowfish]

can we mix moore and melay machines

Hi,

You can refer Zvonksi and Brown , digital systems using verilog/vhdl .it is good book which contains explanation of FSM with codings.

 

[blowfish]

hdl designer fsm

Hi ,

I have some materials which are on FSM modelling using verilog and vhdl.

 

[richardyue]

melay and moore machine implementation

Hi subramanyam,

You said "for designing data path u can choose mealy as is faster."

We know that all digital system can be splitted into "control path" "data path". And "control path" is used to control "data path".

But when to implement "data path" with FSM? Who can give out a simple example?

Best regards,
Davy

Dear Davy,
I'm kind of confused about what you said about the "designing data path u can choose mealy as is faster". Would you like to explain it in more detail? Thanks in advance.

 

[davyzhu]

cpu mealy moore machine

Hi richardyue,

Please ask subramanyam about the question,

Thanks!
Davy

 

[subramanyam]

moore,melay machines

Hii Davy,

Exactly that is what I have learned , but I never thought regarding my data path design statement . It seems to be ur statement is correct but i really want to know from you that is it impossible to design data path using fsm ??

thank you,

subbu.