Variable Binary Counter?

[none]

Hello,

I'm putting together a circuit that uses a binary counter to cycle through
addresses of SRAM. I would like to vary the number of addresses used while
the circuit is running. Does anyone know of a simple way to build a binary
counter with a variable count?

Thanks.

 

[John Fields]

On Sat, 30 Aug 2008 08:18:36 -0400, none <eat@joes.com> wrote:

Hello,

I'm putting together a circuit that uses a binary counter to cycle through
addresses of SRAM. I would like to vary the number of addresses used while
the circuit is running. Does anyone know of a simple way to build a binary
counter with a variable count?

---
Probably, but how about some more details?

JF

 

[none]

John Fields wrote:

On Sat, 30 Aug 2008 08:18:36 -0400, none <eat@joes.com> wrote:

Hello,

I'm putting together a circuit that uses a binary counter to cycle through
addresses of SRAM. I would like to vary the number of addresses used
while
the circuit is running. Does anyone know of a simple way to build a
binary counter with a variable count?

---
Probably, but how about some more details?

JF

I'd like to start out with a binary counter with a count of 0-255, and
either with switches, or preferably a rheostat, slowly lower the maximum
count, hopefully all the way down to 0-1.

 

[Jasen Betts]

On 2008-08-30, none <eat@joes.com> wrote:

John Fields wrote:

On Sat, 30 Aug 2008 08:18:36 -0400, none <eat@joes.com> wrote:

Hello,

I'm putting together a circuit that uses a binary counter to cycle through
addresses of SRAM. I would like to vary the number of addresses used
while
the circuit is running. Does anyone know of a simple way to build a
binary counter with a variable count?

---
Probably, but how about some more details?

JF


I'd like to start out with a binary counter with a count of 0-255, and
either with switches, or preferably a rheostat, slowly lower the maximum
count, hopefully all the way down to 0-1.

run the output of the counter into a DAC (digital to analogue converter)
use a comparitor to compare it to the voltage from a potentiometer
across the same supply as the DAC the output of the comparitor feeds
the reset pin of the counter.

if you really need to use a rheostat instead of a potentiometer
there's probably a way to make that work too.

a pre-built DAC will probably give smoother tuning of the count than a
simple r-2r ladder, but the only one I found locally requires dual supply


Bye.
Jasen

 

[none]

Jasen Betts wrote:

I'd like to start out with a binary counter with a count of 0-255, and
either with switches, or preferably a rheostat, slowly lower the maximum
count, hopefully all the way down to 0-1.

run the output of the counter into a DAC (digital to analogue converter)
use a comparitor to compare it to the voltage from a potentiometer
across the same supply as the DAC the output of the comparitor feeds
the reset pin of the counter.

if you really need to use a rheostat instead of a potentiometer
there's probably a way to make that work too.

a pre-built DAC will probably give smoother tuning of the count than a
simple r-2r ladder, but the only one I found locally requires dual supply


Bye.
Jasen

I think that would work great for my application. Thank you.

 

[Electronworks]

TLC7524 is a parallel input 8 bit DAC that should suffice - from ti (TI.COM)

Rgds

Bill

Electronworks.co.uk



"none" <eat@joes.com> wrote in message
news:48baeec2$0$4002$bbae4d71@news.suddenlink.net...

Jasen Betts wrote:

I'd like to start out with a binary counter with a count of 0-255, and
either with switches, or preferably a rheostat, slowly lower the maximum
count, hopefully all the way down to 0-1.

run the output of the counter into a DAC (digital to analogue converter)
use a comparitor to compare it to the voltage from a potentiometer
across the same supply as the DAC the output of the comparitor feeds
the reset pin of the counter.

if you really need to use a rheostat instead of a potentiometer
there's probably a way to make that work too.

a pre-built DAC will probably give smoother tuning of the count than a
simple r-2r ladder, but the only one I found locally requires dual supply


Bye.
Jasen


I think that would work great for my application. Thank you.