Computer Logics and Digital Design

tshuck

Joined Oct 18, 2012
3,534
What is the purpose of sequential and combinational circuit?
It depends on the application.

With respect to a counter, the sequential portion(flip flops) form the memory of the counter (holding the current count), where the combinational logic forms the input-forming logic(what is the next count, given the current count) and the output-forming logic (perhaps, as a binary-to-BCD decoder).
 

Thread Starter

divaremy

Joined Mar 31, 2014
26
ok for all this automatic timer thing im creating, what are the devices and equipments will i need? i know about switch, photocell and power supply.
 

tshuck

Joined Oct 18, 2012
3,534
ok for all this automatic timer thing im creating, what are the devices and equipments will i need? i know about switch, photocell and power supply.
Knowing what you know, is there a way to make the functionality required, given the current time? If so, what do you think you'd need?
 

tshuck

Joined Oct 18, 2012
3,534
Why don't you sketch what you have? Have you simulated the counter?

As far as the light functions go, try to identify what you need as inputs in order to perform the function. In other words, how could you determine if the count is between two numbers? If you can't, write out the counter states in binary and see if there are any bits that might be a specific state when the count is between the values you are interested in.
 

WBahn

Joined Mar 31, 2012
29,979
Another way to approach it is to identify what counter states you want to turn the lights on and off and then use a register to hold that information until the next change.
 

tshuck

Joined Oct 18, 2012
3,534
here it is
What are we looking at here? If you want as 0-23 count counter, you need, as has been discussed, 5 bits, meaning 5 flip flops.

Additionally, you are attempting to connect the output of the OR gate to the output of the 74154 - I'm not sure what you are trying to do there, but you cannot connect outputs together like this.
 
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