# How do I construct a Down Counter (odd)?

#### Nica Roquid Geñorga

Joined Apr 4, 2016
7

#### GopherT

Joined Nov 23, 2012
8,012
You start by clarifying some details of what you exactly need. Input and output. Speed, other constraints...

#### mcgyvr

Joined Oct 15, 2009
5,394
Yes you do..
You need to learn to include sufficient information in your question..

So far you want something that counts down..
What starts the count?
What happens at the end of the count?
How long is the count?
What type of display?

and more..

#### dl324

Joined Mar 30, 2015
11,230
Is this homework?

#### eetech00

Joined Jun 8, 2013
1,969
Hi

What number does the count begin counting down? Does the count begin at 10 and end at 0? or?

#### Nica Roquid Geñorga

Joined Apr 4, 2016
7
my professor just said that we have to make a down counter (that counts odd number only). I really don't have any idea how to make it

#### Nica Roquid Geñorga

Joined Apr 4, 2016
7

#### Nica Roquid Geñorga

Joined Apr 4, 2016
7
Hi

What number does the count begin counting down? Does the count begin at 10 and end at 0? or?
yes

#### Nica Roquid Geñorga

Joined Apr 4, 2016
7
Yes you do..
You need to learn to include sufficient information in your question..

So far you want something that counts down..
What starts the count?
What happens at the end of the count?
How long is the count?
What type of display?

and more..
my professor just said that we have to make a down counter (that counts odd number only). I really don't have any idea how to make it

#### kubeek

Joined Sep 20, 2005
5,730
Ok, do you know how to make an adder?

#### dl324

Joined Mar 30, 2015
11,230
my professor just said that we have to make a down counter (that counts odd number only). I really don't have any idea how to make it
He had to tell you the maximum and minimum counts and you should have been taught the design process.

For homework, you need to show your work and be guided to a solution. Members are not allowed to do the work for you.

#### Nica Roquid Geñorga

Joined Apr 4, 2016
7

#### WBahn

Joined Mar 31, 2012
26,046
my professor just said that we have to make a down counter (that counts odd number only). I really don't have any idea how to make it
If that is really true -- that you have no idea how to even start or how to even sketch out what it needs to do -- then perhaps it is time to drop this course and retake it (or perhaps the course before it), paying more attention next time.

#### GopherT

Joined Nov 23, 2012
8,012
No. I really don't know.
Make an appointment with your professor, TODAY! Talk to him/her and find out what is needed, what you should read/understand from text or notes to get this done. There is so much background needed to do this assignment and, now that it has been moved to HOMEWORK section, it will take 200 posts and there will still be no answers for you because we do not know where your skill level starts. If you have zero skills, this is not the place to get help. Talk to your professor!

#### ErnieM

Joined Apr 24, 2011
8,053
Since zero is an even number you can simply connect the lowest bit to a "one" and use a standard down counter for the rest.

#### mcgyvr

Joined Oct 15, 2009
5,394
my professor just said that we have to make a down counter (that counts odd number only). I really don't have any idea how to make it
I'm not asking if you know how to make it.. we can help with that if you actually provide the information
But YOU need to tell us exactly what you are trying to make and how it needs to function..

Take 5 pieces of paper..
Write 9 on one, 7 on the other, 5 on another, 3 on another and 1 on the last
Staple them together in order with 9 being the first (on top) and 1 being the last piece of paper (on bottom)..
Voila.. a down counter.. Just flip through the pages to count down..

Now this is along the lines of what we expect..
---------------------
I'm working on a school project where either I'm not paying attention at all or the teacher is sleeping all day long
I need to create a count down counter..
It needs to start at 99 and count down in odd numbers ending at 1..
Each number corresponds to the number of seconds left.
I need the count to display on 2 small 7 segment displays
I need the count to start when I press a start button and reset to 99 whenever I press a reset button
When it gets to 1 it should wait until I press the reset button
I cannot use a microcontroller

#### KaiL

Joined Aug 30, 2014
69
You can do this pretty easily using JK flip flop or D flip flop.

Basically , this will do the counting UP/Down depending on the configuration.

You should be able to continue from here. Assuming you did it right , you should be able to count down. Next you just need to add in a few more configuration and you can count down in odd number.

#### KaiL

Joined Aug 30, 2014
69
May I know what module are you taking right now? This project should be related to what you are currently doing.
Digital electronic module? I remember doing something similar to this before and this is pretty straight forward.

#### dl324

Joined Mar 30, 2015
11,230
my professor just said that we have to make a down counter (that counts odd number only). I really don't have any idea how to make it
Hope we didn't scare you off.

The problem isn't difficult. We just need to know what the constraints are (min/max count, logic restrictions, etc), and what you know or don't know before we can offer guidance.