4 bit up counter

Thread Starter

vead

Joined Nov 24, 2011
629
You fixed it. Your counter would have counted up to 4 and stayed there indefinitely had it been implemented as you had shown (100 goes to 100).
we knew the next state so now why we need to k map



thanks lot tshuck today you taught me lots about digital electronics
 

tshuck

Joined Oct 18, 2012
3,534
we knew the next state so now why we need to k map
Technically speaking, we don't. However, you would need a huge amount of gates to do this. The K-maps are to reduce the input-forming logic, or the logic that will generate the next state values for the inputs to the D flip-flops for the next clock edge. If you don't do the K-maps, you would have to decode each current state value to produce the inputs for the next state and select the correct input accordingly.

The K-maps make your life easier.

thanks lot tshuck today you taught me lots about digital electronics
You are welcome, it's what I'm here for.:)
 

Thread Starter

vead

Joined Nov 24, 2011
629
Technically speaking, we don't. However, you would need a huge amount of gates to do this. The K-maps are to reduce the input-forming logic, or the logic that will generate the next state values for the inputs to the D flip-flops for the next clock edge. If you don't do the K-maps, you would have to decode each current state value to produce the inputs for the next state and select the correct input accordingly.

:)
I understood the function table of Counter IC by datasheets but when we implement counter Ic with flip flop how to understand the table

simple I made up counter with four d Flip flop that count 0 to 7 number now I am having trouble to make datasheet for counter I tried can someone help me to make the table for counter

what is process to make table for up counter using d flip flop

what should we first know step by step to make table
 

WBahn

Joined Mar 31, 2012
29,976
so how to find out next state

truth table
N C B A next state
-- - ------------------------------------
0 0 0 0
1 0 0 1
2 0 1 0
3 0 1 1
4 1 0 0
5 1 0 1
6 1 1 0
7 1 1 1
Well, if you are in state 011, what is the next state you want to go to if this is an up counter? Also, if it is a 4-bit up counter, then don't you need 4-bits of state information (at least)?
 

WBahn

Joined Mar 31, 2012
29,976
I understood the function table of Counter IC by datasheets but when we implement counter Ic with flip flop how to understand the table

simple I made up counter with four d Flip flop that count 0 to 7 number now I am having trouble to make datasheet for counter I tried can someone help me to make the table for counter

what is process to make table for up counter using d flip flop

what should we first know step by step to make table
What table? Next state table? Transition table?

If you made an up counter that only counts from 0 to 7, why did you need four flip flops?

It is still far from clear that you have firmly established what it is that you want this black box to do.

What, exactly, are the inputs to this black box that you are calling a 4-bit up counter? What, exactly, does each input mean?

What, exactly, are the outputs from this black box. What, exactly, does each output mean?

Unless you can clearly and precisely describe the interface to this black box detailing exactly what it is you want the black box to do, you don't stand a chance in hell of putting something inside that black box that will do what you want.
 

Thread Starter

vead

Joined Nov 24, 2011
629
Well, if you are in state 011, what is the next state you want to go to if this is an up counter? Also, if it is a 4-bit up counter, then don't you need 4-bits of state information (at least)?
yes you are correct that's not four bits its 3 bit up counter

table for 3 bit up counter

present state next state
N A B C
0 0 0 0 0 0 1
1 0 0 1 0 1 0
2 0 1 0 0 1 1
3 0 1 1 1 0 0
4 1 0 0 1 0 1
5 1 0 1 1 1 0
6 1 1 0 1 1 1
7 1 1 1 0 0 0
present state I think present state means this
N A B C
0 0 0 0
1 0 0 1
2 0 1 0
3 0 1 1
4 1 0 0
5 1 0 1
6 1 1 0

next state means

N A B C
1 0 0 1
2 0 1 0
3 0 1 1
4 1 0 0
5 1 0 1
6 1 1 0
7 1 1 1
0 0 0 0


that's circuit is very complex for me don't know any idea what i do next


1) how to find out what exactly are the input to counter
2) how to find out what exactly are the output to counter
 
Last edited:

tshuck

Joined Oct 18, 2012
3,534
[...]
1) how to find out what exactly are the input to counter
Minimum, a clock signal, the rest are up to you. Do you want a reset? Do you want to load values into the counter? Do you want to be able to select an up or down count function?

You need to determine the desired functionality before you can design a counter's logic...
2) how to find out what exactly are the output to counter
Typically you want a counter to count, so the count as an output would be nice. Other than that, you could have a signal showing that the counter is at its maximum count value, but, again, this depends on what you want.
 
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