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Frequency Divide by 2.5 - SYMMETRIC - Win ???

J

Jim Thompson

Jan 1, 1970
0
Win claimed a *symmetric* divide by 2.5.

I asked to see the schematic.

Win?

...Jim Thompson
 
W

Winfield Hill

Jan 1, 1970
0
Jim Thompson wrote...
Win claimed a *symmetric* divide by 2.5.
I asked to see the schematic.

Win?

I'm very pleased to show it Jim, but am far too
busy right now to type it in, it'll have to wait
until this weekend. BTW, I didn't mean to imply
it makes a square-wave output, but it does have
evenly-spaced output pulses (assuming square-wave
input). Note, some parts can be saved if the goal
is simply to register the right number of output
pulses per five input cycles... And then we have
Fred, who's not satisfied if we don't always use
the same clock edge (whether leading or trailing).
:>D

Thanks,
- Win

whill_at_picovolt-dot-com
 
J

Jim Thompson

Jan 1, 1970
0
Jim Thompson wrote...

I'm very pleased to show it Jim, but am far too
busy right now to type it in, it'll have to wait
until this weekend. BTW, I didn't mean to imply
it makes a square-wave output, but it does have
evenly-spaced output pulses (assuming square-wave
input). Note, some parts can be saved if the goal
is simply to register the right number of output
pulses per five input cycles... And then we have
Fred, who's not satisfied if we don't always use
the same clock edge (whether leading or trailing).
:>D

Thanks,
- Win

whill_at_picovolt-dot-com

I mis-read "symmetric" as "square" which is why I was yanking your
chain... 'tain't possible ;-)

...Jim Thompson
 
W

Winfield Hill

Jan 1, 1970
0
Jim Thompson wrote...
I mis-read "symmetric" as "square" ...

Right, time to get a 23" computer display?

Thanks,
- Win

whill_at_picovolt-dot-com
 
J

Jim Thompson

Jan 1, 1970
0
Jim Thompson wrote...

Right, time to get a 23" computer display?

Thanks,
- Win

whill_at_picovolt-dot-com

Are there any non-crt displays that large?

...Jim Thompson
 
S

Spehro Pefhany

Jan 1, 1970
0
Are there any non-crt displays that large?

...Jim Thompson

Yes. LCD and plasma. But not cheap.

Best regards,
Spehro Pefhany
 
S

S.M.Taylor

Jan 1, 1970
0
Jim said:
Are there any non-crt displays that large?

...Jim Thompson

Easily. Plasma screens and LCD panels are available.

STeve
 
R

Richard Henry

Jan 1, 1970
0
Jim Thompson said:
Are there any non-crt displays that large?

You can get 4-foot plasma TVs. Has anyone done a computer-monitor
adaptation?
 
J

John Fields

Jan 1, 1970
0
---
Win:

What you're describing isn't a counter/divider, it's a rate multiplier.

Anyway, what are you getting on Fred's case for? He was right; any of
these junk circuits trying to predict where an edge will be will suffer
from phase noise.
---

I mis-read "symmetric" as "square" which is why I was yanking your
chain... 'tain't possible ;-)

---
Jim:

Sure it is, and it's easy.

Just start with 20.

20/2 = 10
---- = 2.5
20/5 = 4

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
20 _| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_|

___ ___ ___ ___ ___ ___ ___ ___ _
10 _| |___| |___| |___| |___| |___| |___| |___| |___|

_________ _________ _________ _____
4 _| |_________| |_________| |_________|


Perfectly predictable edges and minimal phase noise courtesy of 20!
 
U

Uwe Bonnes

Jan 1, 1970
0
: Win claimed a *symmetric* divide by 2.5.

: I asked to see the schematic.

Xilinx Coolrunner II has Flops that may switch on both edges.

always @ (posedge clk or negedge clk)
begin
if (cnt == 4)
begin
cnt <= 0;
out <+ ~out;
end;
else cnt <= cnt +1;

No guarantee for functionallity :)

Bye
 
S

Spehro Pefhany

Jan 1, 1970
0
You can get 4-foot plasma TVs. Has anyone done a computer-monitor
adaptation?
You can just plug a VGA cable into some 42" plasma TVs....

Best regards,
Spehro Pefhany
 
J

Jim Thompson

Jan 1, 1970
0
---
Win:

What you're describing isn't a counter/divider, it's a rate multiplier.

Anyway, what are you getting on Fred's case for? He was right; any of
these junk circuits trying to predict where an edge will be will suffer
from phase noise.
---



---
Jim:

Sure it is, and it's easy.

Just start with 20.

20/2 = 10
---- = 2.5
20/5 = 4

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
20 _| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_|

___ ___ ___ ___ ___ ___ ___ ___ _
10 _| |___| |___| |___| |___| |___| |___| |___| |___|

_________ _________ _________ _____
4 _| |_________| |_________| |_________|


Perfectly predictable edges and minimal phase noise courtesy of 20!

Oh horse pucky! How can you claim "20" is available?

...Jim Thompson
 
W

Winfield Hill

Jan 1, 1970
0
Spehro Pefhany wrote...
You can just plug a VGA cable into some 42" plasma TVs....

These aren't acceptable - too low edge-to-edge pixel count!

Thanks,
- Win

whill_at_picovolt-dot-com
 
W

Winfield Hill

Jan 1, 1970
0
John Fields wrote...
What you're describing isn't a counter/divider, it's a rate multiplier.

Hey, a rate multiplier with a fixed setting is a divider.
Of sorts.
Anyway, what are you getting on Fred's case for? He was right; any of
these junk circuits trying to predict where an edge will be will suffer
from phase noise.

It's a matter of emphasis and useability and of courtesy. :>)

Anyway, consider these two possibilities: 1) the source is
inherently very stable and square (e.g. from a divider), or
2) the resulting x 0.4 frequency is not used with a PLL in
communications and isn't sensitive to small levels of inter-
pulse jitter. I have encountered many such cases in my own
engineering experience.

Thanks,
- Win

whill_at_picovolt-dot-com
 
R

Richard Henry

Jan 1, 1970
0
Spehro Pefhany said:
You can just plug a VGA cable into some 42" plasma TVs....

What is the maximum pixel resolution?
 
S

Spehro Pefhany

Jan 1, 1970
0
Spehro Pefhany wrote...

These aren't acceptable - too low edge-to-edge pixel count!

Acceptable for what? They're okay for spreadsheets and games. I think
the native resolution is 1024 x something or other. I think I'd prefer
a 1600 x 1200 20" LCD for work if my 21" Panasonic is to get replaced.
Sam's Club has a one-time purchase of Philips units on sale rather
cheap right now (< $1K US).

The 24" ones (eg. Apple Cinema) are still pretty pricey, but the size
and the 16 x 9 aspect ratio is pretty attractive. They'll probably
drop a lot in the next year or two.

Best regards,
Spehro Pefhany
 
S

Spehro Pefhany

Jan 1, 1970
0
What is the maximum pixel resolution?

On that size, 852 x 480 (wide VGA). On the 60" it's 1280 x 720.

Best regards,
Spehro Pefhany
 
T

Tim Shoppa

Jan 1, 1970
0
Winfield Hill said:
Jim Thompson wrote...

I'm very pleased to show it Jim, but am far too
busy right now to type it in, it'll have to wait
until this weekend.

What did Fermat write, something about "it is possible to have a
square be the sum of two squares, but that a cube can not be the sum
of two cubes, nor a fourth power be a sum of two fourth powers, and so
on. I have found a
truly marvelous proof of this which is too small to be contained in
this
margin" ?

Tim.
 
A

Aubrey McIntosh

Jan 1, 1970
0
Jim Thompson said:
Oh horse pucky! How can you claim "20" is available?

...Jim Thompson

A 1:20 phase lock loop?
 
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