- #1
muppen
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Homework Statement
I'm a bit at a loss here for a particular assignment we got for one of our labs. I've been using a certain method to derive the k-maps for some circuits, but for this particular one, it didn't really work out too well for some reason. We built and implemented a 4-bit synchronous decade counter. We were then told to make a state diagram, next-state table and a k-map for all the j-k inputs. I'm having a particular issue with the K4/J4 and the K2 maps.
Let me first give you a link to the actual circuit:
http://www.electronics-tutorials.ws/counter/cou14.gif
This is how far I've gotten, I've make a flip-flop transition table, next-state table and also been determining which cells to map with what from it.
http://imageshack.us/f/813/18768245.png/
Is there a flaw in my reasoning? For example, I first take Q1, and check the position 0000 against the next state. I then derive what to place in that position for J1 and K1, and I do the following for all the other positions and Q2-Q4. Am I using the wrong method, or have I mapped something wrong or written something wrong?
Here's how far I've gotten:
http://imageshack.dk//viewimage.php?file=/imagesfree/Fah58500.png
Homework Equations
J1/K1 should always be high, which is correct.
J2/K2 should be Q1Q4'. The J2 is correct, but the K2 is not.
J3/K3 should be Q1Q2, which is correct.
J4/K4 should be Q1Q2Q3 + Q1Q4. I however, get some other results.
Where am I wrong in my reasoning? I know there's another way to solve the K-maps for this counter, by checking previous outputs when the current output toggles, but I've used this method before, and it has worked just fine. Am I marking the positions on the K-map wrong or am I using the wrong method, or does it not apply to these, or what?
I'm grateful for any help.