I need to design a counter diagram that follows a count sequence 0-2-4-1-0 using DFFs.

The characteristic equation for the DFF is Q+ = D. I have the sequence in the present state and next state table but don't know where to go from there.

Present State | Next State|Da |Db |Dc |
000           | 010       | 0 | 1 | 0
010           | 100       | 1 | 1 | 0
100           | 001       | 1 | 0 | 1
001           | 011       | 0 | 1 | 0
011           | 000       | 0 | 1 | 1

I appreciate any help. I have been trying to find a similar example for hours with no luck.

I think what the main thing I need help with is how to go from the state table to the k-map. If what I have done in the state table is correct. So I guess the first question is, is my state table correct?

Thanks for your help

 

Hello,

Perhaps this thread might help:
http://forum.allaboutcircuits.com/showthread.php?t=44399

Bertus

 

count sequence 0-2-4-1-0 using DFFs.

Be sure of your assignment. Your table shows a sequence 0-2-4-1-3-0.

 

Be sure of your assignment. Your table shows a sequence 0-2-4-1-3-0.

Thanks! The 3 shouldn't be in there. I mixed the numbers up with a state graph that I just put together that used that sequence. I couldn't figure out how to edit my post but it should read:

Present State | Next State|Da |Db |Dc |
000 | 010 | 0 | 1 | 0
010 | 100 | 1 | 1 | 0
100 | 001 | 1 | 0 | 1
001 | 000 | 0 | 0 | 1

 

Hello,

Perhaps this thread might help:
http://forum.allaboutcircuits.com/showthread.php?t=44399

Bertus

Thanks for the suggestion. I read that thread but it is more involved than my problem and I'm not quite at that point yet in my circuit knowledge. I am just now trying to learn the basics of these flip flops.

 

Hello,

In the eBook at the top, there is this page on D flip-flops:
http://www.allaboutcircuits.com/vol_4/chpt_10/4.html

An other page with a lot of links is this one on the EDUCYPEDIA:
http://www.educypedia.be/electronics/digitalflipflops.htm

There are more pages like that over there on other digital subjects:

Digital electronics:
Arithmetic circuits D/A-A/D converters Number systems Codes and decoders Flip flops Technology Counters and registers General overview Technology-CMOS Digital logic Memories Technology-TTL Timers and oscillators

Bertus

 

Isn't this just a 3-bit shift register,
with outputs Q1, Q2, Q3
ordered as q2, q1, q3
?

 

4-bit actually; zero counts as information. It's a clever idea but usually homework assignments are very specific on the implementation methods.

 

I figured out the 4-bit requirement, but didn't edit the post because I thought I had provided enough information for the OP.