Question about design of clocking circuit

U

usao

Guest
Disclaimer: I am not a student, but a home hobbyist trying to work out
a problem.

Here's the situation. I have a 1Mhz osc which I want to switch on-off.
The issue is that I don't want the on-time of the clock to change
depending on when the switch is thrown.
Im looking not for answers, but for pointers or suggestions on how I
should work this problem. The angle I have tried so-far is to use a
edge triggered flip-flop to catch the output of the input osc ANDed
with the switch input. The idea here is that if I catch the edge, and
it's active, then I can send this through a one-shot, or somthing else
to keep the width of the pulse the same size.
However, this seems kind of complicated, and may require a debounce on
the switch as well...
Is there some simpler approach im missing?
Thanks,
Ron (rwatkins at dssolutions dot com)
 
usao wrote:
Disclaimer: I am not a student, but a home hobbyist trying to work out
a problem.

Here's the situation. I have a 1Mhz osc which I want to switch on-off.
The issue is that I don't want the on-time of the clock to change
depending on when the switch is thrown.
Im looking not for answers, but for pointers or suggestions on how I
should work this problem. The angle I have tried so-far is to use a
edge triggered flip-flop to catch the output of the input osc ANDed
with the switch input. The idea here is that if I catch the edge, and
it's active, then I can send this through a one-shot, or somthing else
to keep the width of the pulse the same size.
However, this seems kind of complicated, and may require a debounce on
the switch as well...
Is there some simpler approach im missing?
Click to expand...
Yes, you just have to synchronize your on/off with the clock with a FF.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
 
On 2 Aug 2004 12:06:13 -0700, usao wrote:

Disclaimer: I am not a student, but a home hobbyist trying to work out
a problem.

Here's the situation. I have a 1Mhz osc which I want to switch on-off.
The issue is that I don't want the on-time of the clock to change
depending on when the switch is thrown.
Im looking not for answers, but for pointers or suggestions on how I
should work this problem. The angle I have tried so-far is to use a
edge triggered flip-flop to catch the output of the input osc ANDed
with the switch input. The idea here is that if I catch the edge, and
it's active, then I can send this through a one-shot, or somthing else
to keep the width of the pulse the same size.
However, this seems kind of complicated, and may require a debounce on
the switch as well...
Is there some simpler approach im missing?
Thanks,
Ron (rwatkins at dssolutions dot com)
Click to expand...
HArd to say without more osc circuit details but I'm quessing this
osc is made with inverters (?) Why not use a SPDT or dpdt switch
with one side to turn on the OSC supply and the other (when off) to
ground out the timing cap to return it's initial condition to 0V?
--
Best Regards,
Mike
 
In article <dc312199.0408021106.32a7e7a4@posting.google.com>,
usao <ron@argus.lpl.arizona.edu> wrote:
Disclaimer: I am not a student, but a home hobbyist trying to work out
a problem.

Here's the situation. I have a 1Mhz osc which I want to switch on-off.
The issue is that I don't want the on-time of the clock to change
depending on when the switch is thrown.
Im looking not for answers, but for pointers or suggestions on how I
should work this problem. The angle I have tried so-far is to use a
edge triggered flip-flop to catch the output of the input osc ANDed
with the switch input. The idea here is that if I catch the edge, and
it's active, then I can send this through a one-shot, or somthing else
to keep the width of the pulse the same size.
However, this seems kind of complicated, and may require a debounce on
the switch as well...
Is there some simpler approach im missing?
Thanks,
Ron (rwatkins at dssolutions dot com)
Click to expand...
Clk in
-------------------------------------------
! NOR -------- Output
! ---
! DBSW !--------! !
! ----------!D ! !
------------!Clk ! !
! Q/ !----------
!--------!

DBSW = debounced switch

You can use the other section of a dual FF to debounce the switch.

--
--
kensmith@rahul.net forging knowledge
 
Rene Tschaggelar wrote:
usao wrote:

Disclaimer: I am not a student, but a home hobbyist trying to work out
a problem.

Here's the situation. I have a 1Mhz osc which I want to switch on-off.
The issue is that I don't want the on-time of the clock to change
depending on when the switch is thrown.
Im looking not for answers, but for pointers or suggestions on how I
should work this problem. The angle I have tried so-far is to use a
edge triggered flip-flop to catch the output of the input osc ANDed
with the switch input. The idea here is that if I catch the edge, and
it's active, then I can send this through a one-shot, or somthing else
to keep the width of the pulse the same size.
However, this seems kind of complicated, and may require a debounce on
the switch as well...
Is there some simpler approach im missing?


Yes, you just have to synchronize your on/off with the clock with a FF.

Rene
Click to expand...
it can be done even simpler with a latch,

____ ___
gatesignal --------|D Q|--------| |
| | | & |---- CLKout
| | +---|___|
CLK ---------+----o|LE | |
| |____| |
+---------------+

-Lasse
 
Rene Tschaggelar wrote:
usao wrote:

Disclaimer: I am not a student, but a home hobbyist trying to work out
a problem.

Here's the situation. I have a 1Mhz osc which I want to switch on-off.
The issue is that I don't want the on-time of the clock to change
depending on when the switch is thrown.
Im looking not for answers, but for pointers or suggestions on how I
should work this problem. The angle I have tried so-far is to use a
edge triggered flip-flop to catch the output of the input osc ANDed
with the switch input. The idea here is that if I catch the edge, and
it's active, then I can send this through a one-shot, or somthing else
to keep the width of the pulse the same size.
However, this seems kind of complicated, and may require a debounce on
the switch as well...
Is there some simpler approach im missing?


Yes, you just have to synchronize your on/off with the clock with a FF.

Rene
Click to expand...
its even simpler with a latch

____ ___
gatingsignal ---------|D Q|------| |
| | | & |---- Gated CLK
CLK --------------+--o|LE | +--|___|
| |____| |
+------------+

Lasse
 
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