Re: Debouncing....at About 1Mhz

On Thu, 08 Nov 2007 12:01:51 GMT, JosephKK
<joseph_barrett@xxxxxxxxxxxxx> wrote:

John Larkin jjlarkin@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx posted to
sci.electronics.design:

On Wed, 07 Nov 2007 03:13:10 GMT, JosephKK
<joseph_barrett@xxxxxxxxxxxxx> wrote:

D from BC myrealaddress@xxxxxxxxx posted to sci.electronics.design:

On Mon, 05 Nov 2007 07:05:08 -0800, John Larkin
<jjlarkin@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

On Mon, 05 Nov 2007 07:25:10 -0600, John Fields
<jfields@xxxxxxxxxxxxxxxxxxxxx> wrote:

On Sun, 04 Nov 2007 20:59:04 -0800, John Larkin
<jjlarkin@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

On Sun, 04 Nov 2007 20:06:45 -0800, whit3rd <whit3rd@xxxxxxxxx>
wrote:

On Nov 4, 9:07 am, John Larkin
<jjlar...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
On Sat, 03 Nov 2007 17:16:56 -0700, whit3rd
<whit...@xxxxxxxxx> wrote:
So, use a nonretriggerable monostable with rising clock

So what happens when a really fast spike fires both
one-shots? What happens when an edge comes in just about the
time one or both one-shots is timing out?

The problem, as stated, requires a circuit to operate in four
different phases:
Phase A: wait for a rising edge, go high when it does
Phase B: stay high, ignore edges for 'a while'
Phase C: wait for a falling edge, go low when it does
Phase D: stay low, ignore edges for 'a while'

So, something with two monostables or latches or whatever is
required,
because the four states require two bits of state information.
And there are two time periods of some (presumably known)
duration to
be part of the mix. It's required BY THE PROBLEM to have some
kind of one-shot to handle that timing, unless you can use
higher- speed


<snip>


Ok..if I hairballize your circuit a bit :)
D from BC

OK here is my suggestion:


5k
20 pF || ___
.-||-o-----|___|- 5v
| || |
| |
__ .-o-----. __
gnd --\ \| .-------------------| \
| | | | )o-
o--------o/__/| | .---|__/ | __
| | | | '-------| \
| | | | | )o-----o
| 9602 | )---------------)---' '--|__/ |
| | | | | | |
| '--o----' | | | |
| | | | '--+ +---'
| | | | \ /
| | | | X
| '--------------------| | / \
| | | .--+ +---.
| | | | |
| | | | |
| 5k | | | __ |
| 20 pF || ___ | | '--| \ |
| .-||-.-----|___|- 5v | | | )o--'
| | || | | | '-----|__/
| | | | | |
| __ .-------. | | |
'----\ \| | __ | | |
| | o-------| \ | | |
5v --o/__/| | | )o--)---)--------'
| | .--|__/ | |
| | | | |
| | | | |
9602 | '----)----------' |
'--o----' | |
| | |
| | |
----------o--------------'











A fast input spike can fire both one-shots! Then the fun begins.

John

Maybe, they are cross interlocked.

Yup. After they both fire, roughly 40 ns after, the fun begins.

Another hairball, but at least it's a bit simpler. Still too slow,
even when it doesn't screw up.

John

.

Relevant Pages

  • Re: Debouncing....at About 1Mhz
    ... the time one or both one-shots is timing out? ... A fast input spike can fire both one-shots! ... After they both fire, roughly 40 ns after, the fun begins. ...
    (sci.electronics.design)
  • Re: Weekend one-shot timer design
    ... one-shots with only 5 components instead of 30 for one. ... exercise. ... But what fun is playing with ... Website: http://webpages.charter.net/dawill/tmoranwms ...
    (sci.electronics.design)