4-bit synchronous counter which is counting upwards from 3 to 12?

Thread Starter

Sedus

Joined Mar 25, 2021
31
I finally made simple 4-bit synchronous counter and somehow its start from 3 as well, but I have no idea how to solve completely. I know how to do with asynchronous counter but this synchronous now. I insert my basic 4-bit synchronous counter.gdgdfgd.png
 

ericgibbs

Joined Jan 29, 2010
12,465
hi,
In an actual circuit a Clear pulse would be applied, usually at power up.
This ensures all Counter are in the cleared state before applying the count input pulses.

E
 

Thread Starter

Sedus

Joined Mar 25, 2021
31
Good for you. I tried to figure out the whole thing but I didn't get any further, I understand how synchronous counters works but thats it, I can still trying with this preset and clear thing but I dont know what am I exactly doing. I can easily do asynchronous counter which is counting 3 to 12, but this...
 

dl324

Joined Mar 30, 2015
12,789
I tried to figure out the whole thing but I didn't get any further
If you post your work, we can see what method you're using and where you're having problems.
I understand how synchronous counters works but thats it, I can still trying with this preset and clear thing but I dont know what am I exactly doing.
Synchronous counters don't rely on preset or clear.

The counter you were asked to design isn't very complicated. I only needed the 4 flip flops and half a dozen gates.
 

Thread Starter

Sedus

Joined Mar 25, 2021
31
So, I used AND gate which is connected to 1,4 and 8 Q output so it should switch at 12, and the other side of gate I connected to 1 and 2 P input so it should be start at 3, it works but the problem is when the counter switch from 7 to 8 for something the gate's input value was 15 instead of 8, somehow 1,2 and 4 output is delayed a little bit before going low when switch to 8. So I made a 3-7 synchronous counter by mistake. I cant fix this, so here I am, I tried, I would appreciate some real help or guidance about I'm on the right track or completely wrong?
 

dl324

Joined Mar 30, 2015
12,789
I would appreciate some real help or guidance about I'm on the right track or completely wrong?
Textual descriptions of circuits is a non-starter for most of us. If you're serious about getting help, post a schematic and show your work.
 
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