0-5 Counter...Urgent Help!!!!

Thread Starter

kjs_123

Joined Oct 16, 2008
22
Right, I designed a 0-5 Counter as shown below which counts 0-5 perfectly
http://img92.imageshack.us/img92/834/05yl0.jpg

Now I am kinda stuck on two things:
1. I have to set the D input to High to count from 0-5(although it is counting 0-5) and when low do the reverse.
2. add an extra input which when set high should hold its value and when set low should count normally.......

*By adding a NOT gate to RESET the counter counts.....but whereas if the RESET is low then it doesn't count*

I know the above is a basic digital design query....but as I am a beginner please help me out.....

Thanks for looking
KJ
 

Thread Starter

kjs_123

Joined Oct 16, 2008
22
If you designed it, you must know how it operates, and so knowing which D input to set should be a snap. Likewise a hold/count gate.
Yeah i know how it works as I drew a state diagram and all.....
But in the second part where it says "add an extra input which when set high should hold its value and when set low should count normally"

Where should i put the extra input?:confused:
 

beenthere

Joined Apr 20, 2004
15,819
It has to stop the clock into all flip flops. Moreover, it has to freeze the logic level at the correct state. Those flip flips clock on the transition, but it is not evident if it high to low or the converse. What you do not wish to happen is a clock transition at the time you apply the signal to block the clock.
 

Thread Starter

kjs_123

Joined Oct 16, 2008
22
beenthere....I was just testing few things on my original digital design and noticed that If I put the RESET at high the clock did count from 0-5 but if the RESET was left at low then the clock did not count.....so is that answering my question below:confused:
I have to set the D input to High to count from 0-5(although it is counting 0-5) and when low do the reverse
 

beenthere

Joined Apr 20, 2004
15,819
If it's a D flip flop, the stae of the D input is transfered to the output when the clock pulse id applied. The SET and RESET inputs always override the clock and D inputs.

You might benefit from obtaining the data sheet and reading how a 7474 flip flop works.
 
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