# counter question

Discussion in 'Homework Help' started by hazim, Jan 23, 2008.

1. ### hazim Thread Starter Active Member

Jan 3, 2008
419
13
hi
in any counter; for example the one i'm building, a 0-15 counter; how do i make this counter reachs a certain number and stops and then this number stays displayed by the 7-segment display...my aim is to let the counter count from 0 till 15 and then the counter stops at 15 where the 7-segment displays 15...any help?

2. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
In order for 7 segment displays to show the two digit value of 15, you will need two displays. With external logic, a single binary counter will do, but it might be easier with two decimal counters.

Are you using standard logic for the counter, or are you doing an exercise to make a discreet design?

3. ### hazim Thread Starter Active Member

Jan 3, 2008
419
13
i'm doing a project and my instructor needs me to work and design by myself....i designed an external circuit to obtain two digits on two 7 segment displays from the 7493 binary counter....

4. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Then you will want some external logic to stop the clock when the count is 15.

5. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
Hmm - since this is "homework", shouldn't it be in the "homework" section?

6. ### hazim Thread Starter Active Member

Jan 3, 2008
419
13
maybe you are right SgtWookie...it's a final course project. i'am asking about the concept of this external circuit beenthere

7. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Think of a logic gate that would change its output when the counter state went to 15 and whose output would disable another gate from passing any further clock pulses.

8. ### luck New Member

Jan 25, 2008
8
0
you can use a latch that triggers before the display such that when the MSB would go from high to low you lock the 15 value in the display; you can also use this latch to stop the clock/input source for good measure.

9. ### hazim Thread Starter Active Member

Jan 3, 2008
419
13
I used AND gates to get 1 when the counter reaches 15, and then i connected this 1 with the clock signal to the inputs of a NOR gate and i connected this final output from the NOR gate to the clk input of the counter....It's solved now.thanks.