# Digital counter with acknowledgement

Discussion in 'Electronic Design' started by Baroje, Dec 11, 2003.

1. ### BarojeGuest

Hello!

I need a digital counter which has the ability of sending the
acknowledgement signal on one of its outputs! I need to be 100 percent sure
that counter is incremented when button is pressed or some other event ocur!
When counter is incremented electrical signal must be send to one of the
counter outputs so that some other device can know for sure that the counter
was inrcemented.

Where can I buy counter with this ability or if not how can I modify one of
the existing counters to act like I want and need???

TNX

2. ### Mario TramsGuest

You might use the least significant bit of your counter as feedback
information (assuming you are speaking about a simple binary counter).
This LSB will toggle with every increment operation.
You could also combine this with a D-FlipFlop that stores the
old LSB for one clock cycle and you XOR the old and the current
LSB. This provides an high-pulse during the clock cycle following
the increment.

Regards,
Mario

3. ### Paul BurkeGuest

What kind of counter? Discrete logic? Decimal? How many bits/ digits?

You could do it by latching the counter contents with a clock faster
than the incoming counts, and using a comparator to compare current
state with last. Comparator output is true when a!=b. Or to be really
sure it incremented, a < b. But then you don't know it incremented by
only one...

Paul Burke

4. ### BarojeGuest

I'm sorry I don't think I put this correctly!

I have a counter with 6 digits display ( I don't have it but that is what I
need).
The counter is incrementin when the button is pressed, and the digits are
showing n+1.

What I need is some electrical signal of acknowledgement from the counter
that this incrementing has realy happend!

I know you would say why do you need that when there is a 6 digit display??
Well it's matter of safety and distributed control!

So can anybody tell me where can I buy a device like that, or the closest
one that can be slightly modified to perform lika I want to!

5. ### YDGuest

If you can use both edges of the clock, try this. You'll need the
counter, a latch and a comparator. The latch holds the current count,
the positive edge advances the counter so the comparator's (A=B)
output goes false, run it through an inverter if needed. The negative
edge updates the latch with the new count and (A=B) goes true again.

Of course, this doesn't tell you whether the counter incremented by
one or by next Thursday, an adder with A=count and B=1 between the
latch and comparator will help this. (A=B) will be false at all times
except when the counter has advanced but the latch hasn't yet updated.
To be totally fail-safe you can play around with the clock pulse and
some latches.

- YD.