# Help me understand Counters

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#### Vicountboo

##### Newbie level 5
Counters

Hello
I need some help in understanding about Counters.
-Why do we use it and
-When do you know you need to use a 12 bit or 8 bit counter instead of a 4 bit counter?
Thanks for help.

#### WA

##### Member level 4
Re: Counters

A counter is a time-based and a counter based application.

What I mean is that it's used to syncronize other circuits.
For example, If I want one gate to turn on after another gate, I can use a counter.
The counter starts at zero. and (usually binary) begins counting up 1,2,3...
So lets say gate 1 activated and sent output to another gate. I could set an and-gate in circuit and tie one input to count 3.
Now this circuit will not allow anything through until the counter is at three.

Counters can be used as time delays, clock circuits (for telling time) etc...

As for the size of counter (4,8,12 bits)? This depends on how high you want your counter to count.
4- bit = 0-15
8- bit = 0-255
12- bit = 0-4095
As you can see, The more bits, the higher your counter can count. It is up to the designer to see how high a count they need.
The rule of thumb for counters is that they are in powers of 2
ex. 2^x where x is any positive number.
So 2^2 = 4, 2^3 = 8, 2^4 = 16 etc...

I hope this helps somewhat.
wa

#### papyaki

Re: Counters

Hi,

h**p://www.eelab.usyd.edu.au/digital_tutorial/part2/counter01.html

* = t

#### Kevin Weddle

Re: Counters

I have had an experience with a BCD counter. I wanted to use a counter fed to a decoder. But the BCD counter has 0 - 15 outputs. I think they should call it a counter decoder.

#### ipcore

##### Member level 2
Counters

based on the time interival you need 2^n

#### jay_ec_engg

##### Full Member level 3
Re: Counters

no. of bits used to design counter depends on ur application... like if u want counting upto4 u need 2 bits.. if u want 256 then 8 bit.. and accordingly.....
generaly counters are used to count incoming data... like frames.... samples.... etc..... or u can say to find the time interval.... say ur clokc is of 10Mhz( 100ns) and u want to count for 300ns..( 3 counts)...... like that... for what purpose u need counters ??

##### Newbie level 3
Re: Counters

Kevin Weddle said:
I have had an experience with a BCD counter. I wanted to use a counter fed to a decoder. But the BCD counter has 0 - 15 outputs. I think they should call it a counter decoder.

Are you sure that your BCD counter has 0 - 15 outputs. I think that BCD counter has 4 data outputs, and it counts only 0,2,3,4,5,6,7,8,9 in binary cod. (like UCY7490).

0 -15 outputs has a "1 of 15 counter" or 4bit demultiplexer.

#### Kevin Weddle

Re: Counters

No, it has 0 - 15 outputs. This makes it a counter decoder don't you think?

#### WA

##### Member level 4
Re: Counters

The BCD has 4 inputs.
Because there are 4 input, there must be 15 outputs.

Since the primary use of BCD is numerical use. the remaining outputs are not used. The outputs (BCD 0-9) is just that. But BCD outputs (10-15) are patterns (like small h etc) are generally not used.

As the designer/implementer, it is up to me to use these or not. If I don't need (or want), then I must ensure the conditions don't exist for these unwanted outputs.

hope this helps in understanding BCD's
wa

#### Kevin Weddle

Re: Counters

BCD normally means the count goes from 0 to 9. That is correct. The count is 0 to 9 with a binary output representative of the the number of pulses. So you should have 4 output lines that only count 0 to 9 and start over. However, this was not the case.

#### Serg_SV

##### Member level 3
Counters

You must take book about digital schematic and boleava algebra

#### ozek

##### Newbie level 5
Re: Counters

Hi,
look at Digital design
Morris MANO

#### starfish

##### Member level 2
Re: Counters

Counters are used in many applications.................

They basically count the clock pulses supplied to them..........

Can be used for timing control of some circuitry............

4bit , 8 bit , 12 bit etc counter length depends on ur application......

a 4 bit counter can max count from 0-3
a 8 bit counter can max count from 0-255

In general a counter of n bits can count from 0 to (2^n-1)

#### mopengfei

##### Member level 1
Counters

this is true that the counter of n bits can count any number from 0 to (2^n-1),it is very useful i

#### lambtron

##### Full Member level 5
Re: Counters

And now for something completely different: some counters are bidirectional, meaning that they can count up AND down. This is done by having a combination of inputs instead of just a single clock. For example, such counter might have both Clock and Direction inputs to control up/down counting.

This is very useful for applications in which the physical position of something is to be monitored with an incremental encoder. This is a device with TWO output clocks that are 90° out of phase with each other (i.e., "quadrature" encoded). An incremental encoder can be connected to a quadrature counter. The counter will count up when the encoder turns clockwise and down when the encoder turns counterclockwise. The physical position can move arbitrarily back and forth all day long and, at the end of the day, the counter will correctly indicate the position.

#### neils_arm_strong

##### Full Member level 5
Counters

counters are used for counting,time delays etc.The no of bits of the counter depends on the maximum count that is required.

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