# Sequential circuits help

Thread Starter

#### Andreea Blaga ت

Joined Jun 26, 2015
15
Hello,
I am currently studying for my exam, and I got few exercises left. I came across this exercises that I really don't know how to solve neither I found the solution anywhere.
"A sequential circuit has one input (X) and one output (Z). Design a digital system that makes the output Z = 1 if and only if the total number of 1's received is divisible by 3 (for example, 0, 3, 6, ) or total number of 0's received is an even number greater than zero (nine states are sufficient)."
I have no idea how to solve this. Does anyone know something about it?
Any help will be much appreciated, thanks in advance.

#### WBahn

Joined Mar 31, 2012
26,398
Try tackling them one at a time.

Design a machine that will output a HI if the number of 1's received is divisible by 3.

Then design a machine that will output a HI if the number of 0's received is an even number greater than 0.

How could you combine the output of these two machines to give the desired final result requested?

#### RBR1317

Joined Nov 13, 2010
610
This is a sequential circuit so it will be clocked. Do you need to design the data input clocking circuit, or can you assume that a "1" input will advance the "1" counter and a "0" input will advance the "0" counter?

Thread Starter

#### Andreea Blaga ت

Joined Jun 26, 2015
15
This is a sequential circuit so it will be clocked. Do you need to design the data input clocking circuit, or can you assume that a "1" input will advance the "1" counter and a "0" input will advance the "0" counter?
It doesn't really say how to implement it, just to design it, but i think the second one would be more appropiate.

Thread Starter

#### Andreea Blaga ت

Joined Jun 26, 2015
15
Try tackling them one at a time.

Design a machine that will output a HI if the number of 1's received is divisible by 3.

Then design a machine that will output a HI if the number of 0's received is an even number greater than 0.

How could you combine the output of these two machines to give the desired final result requested?
I believe with some logic gates or multiplexers to choose between the two?

#### WBahn

Joined Mar 31, 2012
26,398
So take the first step -- design a machine that will output a HI if the number of 1's received is divisible by 3 (or do the other one first -- your choice).

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