[Premium-Rx] 3030 keypads

John Perlick p at mn.rr.com
Tue Jul 1 19:03:56 EDT 2003 

Gary G brought up some good points, for Form-C switches, and yes, you can
make an excellent hardware debounce with SPDT switches.  And, he is right,
no one ever makes SPDT switches in keypads or keyboards.  So you are left
with software debounce.

When I say software, I guess this really would be firmware.  In any
keyboard, there is a microprocessor (or microcontroller) which reads the
matrix keyboard switches (typically an 8051 or Z-80 or something related).
The uP also serializes the data and sends it to the computer.  All the
computer knows is that a "C' key was pressed once.  The micro usually
fulfills the repeat function in the keyboard.

In the case of keypads, which are often matrixed also (if matrixed is a
word), then this debounce "software" function is also usually done in the
local micro.   This is not something that  you see running in DOS software.

The software debounce typically does a couple of things (that are
accomplished MUCH more easily in software than in hardware):  First, it will
see a key closure.  It will watch to see that the key stays closed for a
certain amount of time (not bouncing).  THis is a noise filter--assuming
that you might have had a noise pulse look like a key closure, but typically
not a few consecutive reads.  If they key is closed for 3-5 consecutive
reads, then you assume you have a valid key hit.  Then you start a second
read sequence to see that the key is opened within a certain time.  If not,
then you assume you want multiple characters.  And, finally, when you
finally do read an open on the key read, you assume that the key is open and
you ignore any possible closure for a short interval (this is the actual
debounce).  So, keypad/keyboard debouncing is not trivial, and best done in
firmware.  Yes, software can lock up or screw up (my keyboard does once a
year or so) so you have to deal with that.  On the other hand, it is much
more immune to noise this way.  Fast is really not the point...even with a 4
MHz clock (typical for most keyboards) you can do all of this debouncing
MUCH faster than anyones  fingers can move!  So, fast hardware gets you
nothing because all you are doing is slowing down fast hardware for noise
immunity.  I do like the last comment....I'd love to bounce...just not on my
keyboard.

John
K0UM
----- Original Message -----
From: "Henry Kolesnik" <wd5jfr at oklahoma.net>
To: "John Perlick" <p at mn.rr.com>; "refmon" <monitor at referencevideo.com>
Cc: <premium-rx at ml.skirrow.org>
Sent: Tuesday, July 01, 2003 4:02 PM
Subject: Re: [Premium-Rx] 3030 keypads


> I may be a off on this but I would think a hardware debounce would be much
> more effective than software debounce because:
> 1. it's a hardware feature that's not wanted or a malfunction..
> 2. hardware would be faster!
> 3. firmware would be the second choice..
> 4. don't waste software doing something that easily done in hardware
unless
> you've got the resources and may need bounce later..
> 5. when would anyone want bounce or the ability to control it in software?
>
> tnx
> 73
> hank wd5jfr
> ----- Original Message -----
> From: "John Perlick" <p at mn.rr.com>
> To: "Henry Kolesnik" <wd5jfr at oklahoma.net>; "refmon"
> <monitor at referencevideo.com>
> Cc: <premium-rx at ml.skirrow.org>
> Sent: Monday, June 30, 2003 2:22 PM
> Subject: Re: [Premium-Rx] 3030 keypads
>
>
> > Keypad debouncing is best done in software...
> > ----- Original Message -----
> > From: "Henry Kolesnik" <wd5jfr at oklahoma.net>
> > To: "refmon" <monitor at referencevideo.com>
> > Cc: <premium-rx at ml.skirrow.org>
> > Sent: Monday, June 30, 2003 12:36 PM
> > Subject: Re: [Premium-Rx] 3030 keypads
> >
> >
> > > John
> > > That sounds like a great idea.  I've done a bit of snooping and if I
> read
> > it
> > > right Cubic uses Grayhill 88JB2 which is available from Digi-Key for
> > $27.74.
> > > I wonder if anyone can confirm this number as I would like to have
> > > bounceless keypads on my A model.
> > > 73
> > > hank wd5jfr
> > > ----- Original Message -----
> > > From: "refmon" <monitor at referencevideo.com>
> > > To: "Carcia, Frank A. HS" <francis.carcia at hs.utc.com>; "'Herschel
> > > McCullough'" <w5mc at austin.rr.com>; "Al Klase" <skywaves at bw.webex.net>
> > > Cc: <premium-rx at ml.skirrow.org>
> > > Sent: Monday, June 30, 2003 12:30 PM
> > > Subject: Re: [Premium-Rx] 3030 keypads
> > >
> > >
> > > > Hi Frank et al,
> > > >
> > > > As far as I can determine, all the keypad switch assy's are the
> > > same...it's
> > > > the overlay and firmware that varies by model & options.  I know you
> > have
> > > a
> > > > few other models...I can't speak for them, but do any of the keys on
> > 3512,
> > > > etc bounce?
> > > >
> > > > I still find it highly suspect that all 3030A's so far have baggy
> > overlays
> > > > and bouncy switches....all 3030's have firm overlays and no bounce.
> > > Before
> > > > everyone runs out and buys new switches, let's figure out if all the
> > > 3030A's
> > > > have bad keypads or if they're simply not debounced.  As a start, I
> will
> > > > pour through my manuals .. failing an answer there, I'll check panel
> > > > interfaces between 3030A and 3030, including PC board # and rev.  If
> > > > everything there is the same, I'll swap a known-good keypad, which
is
> a
> > > ton
> > > > of work, and see if that makes a difference.
> > > >
> > > > John Collins
> > > > ________________________________________________
> > > > ----- Original Message -----
> > > > From: "Carcia, Frank A. HS" <francis.carcia at hs.utc.com>
> > > > To: "'Herschel McCullough'" <w5mc at austin.rr.com>; "Al Klase"
> > > > <skywaves at bw.webex.net>
> > > > Cc: <premium-rx at ml.skirrow.org>
> > > > Sent: Monday, June 30, 2003 06:13 AM
> > > > Subject: RE: [Premium-Rx] 3030 keypads
> > > >
> > > >
> > > > > I have found a number of different key pad covers going through
the
> > > Cubic
> > > > > stash. I
> > > > > have not found a perfect match for the 3030 yet but have some
close
> > > ones.
> > > > > They appear
> > > > > to just have a backing that peals off then the pad sticks on the
> front
> > > of
> > > > > the panel.
> > > > > They appear to have no effect on bounce just a simple membrane. I
> will
> > > > look
> > > > > for switches
> > > > > if someone can give me a part number or an idea of what they look
> > like.
> > > I
> > > > > found a number of
> > > > > push buttons but have not looked into the configuration.      fc
> > > > >
> > > > >
> > > > > -----Original Message-----
> > > > > From: Herschel McCullough [mailto:w5mc at austin.rr.com]
> > > > > Sent: Saturday, June 28, 2003 11:09 AM
> > > > > To: Al Klase
> > > > > Cc: premium-rx at ml.skirrow.org
> > > > > Subject: Re: [Premium-Rx] 3030 keypads
> > > > >
> > > > >
> > > > > Al, John, etal. as I see my 2 key pads,  the front printed
membrane
> > has
> > > > > become  " de-laminated "  my words.. away somewhat from the button
> > > > surface,
> > > > > and if I rub this face it will for a short time STICK back as it
> > should,
> > > > and
> > > > > the button action seems good to fair in feel and proper responses
> > during
> > > > > this time..  but after a short time the membrane face comes away
and
> > > then
> > > > > when you actuate a key / button it typically will take 2 efforts
to
> > get
> > > > the
> > > > > proper response..  a new key pad I think would make these false
> > > conditions
> > > > > go away.. I would as a personal preference prefer more response or
> > > > positive
> > > > > action when a keypad action is iniated. this is just a personal
> want..
> > > > > albeit false, in my mind I am making a more positive command
request
> > and
> > > > > report..  this might very well be available as a part of replacing
> > these
> > > > > pads with new ones that we might order..
> > > > >
> > > > > John compares the keypads between a 3030 and a 3030a  ..  and true
> to
> > > his
> > > > > findings, my unit is a 3030a and has the bubbly or mushy pad
faces..
> > my
> > > > > hour readings indicate on the left unit 4456 and the right unit
> 7104..
> > > I
> > > > > often think about disconnecting these meters , during quite times
or
> > low
> > > > > volume, the constant  " Ticking " or pulse action of the meters
> annoys
> > > me
> > > > > somewhat..but I haven't done it yet..  All of my modules are
sealed
> > and
> > > > > unbroken..  S/Ns between the same modules are not all that close..
> not
> > > > using
> > > > > my sig generator, but using the same signal source and feeding
both
> > > units
> > > > > thru my Stridsberg coupler, all readings are very similar, not a
> > > > noticeable
> > > > > or visible difference in meter or audio actions.. Back to the
> original
> > > > > problem.. I hung [ Texanise ] suspended the front control panel
from
> > the
> > > > > ceiling and overshifted the operating positions, the receivers
both
> > > > respond,
> > > > > the audio board or pin and wiring is the area where my problem
is..
> I
> > > > > overshifted the control panel both ways and the fault tracked with
> the
> > > > right
> > > > > control section.. I used  # 12  romex conductors to jumper power
to
> > the
> > > > > respective receiver that I was testing..   so I never got into
> > swapping
> > > > > modules , as you know and I found out, the audio driver board is
> > mounted
> > > > on
> > > > > the back of the front control panel.. When I re- assemble this ..
I
> > will
> > > > > swap audio boards, that will pretty much be the final test to
> isolate
> > > the
> > > > > fault.. I have however looked very close at the brown @$%^
> connectors
> > > and
> > > > > each units wiring seems in order..  but I got into the keypad area
> and
> > > now
> > > > > have 198 parts spewed around that will need re-assembly before I
can
> > > > resume
> > > > > testing for the original problem..
> > > > > I followed last weeks keypad discussion with keen interest, so it
> just
> > > > > seemed like I was already in that area and partially apart , to
just
> > go
> > > > > ahead and explore this keypad issue, and try and find a solution
> while
> > I
> > > > was
> > > > > at it..
> > > > >
> > > > > All feedback or other 3030a issues will be greatly welcomed, but
> this
> > > > pretty
> > > > > much concludes my 3030A report till Monday sometime after talking
> with
> > > > > someone at Grayhill about replacement keypads.. thanx for the
> > bandwidth
> > > > > 73  mac/mc  w5mc
> > > > > ----- Original Message -----
> > > > > From: "Al Klase" <skywaves at bw.webex.net>
> > > > > To: "Herschel McCullough" <w5mc at austin.rr.com>
> > > > > Cc: <premium-rx at ml.skirrow.org>
> > > > > Sent: Saturday, June 28, 2003 5:53 AM
> > > > > Subject: Re: [Premium-Rx] 3030 keypads
> > > > >
> > > > >
> > > > > > Do we know for sure that it's the keypads causing the
> > > > > > problem rather than lack of proper de-bouncing in the
> > > > > > electronics?
> > > > > >
> > > > > > Al
> > > > > >
> > > > > > Herschel McCullough wrote:
> > > > > > > The Grayhill web site still shows this style that is used with
> the
> > > > 3030
> > > > > > > ..  some others of you might check it out as well and see what
I
> > > might
> > > > [
> > > > > > > very likely ] be overlooking and lets discuss and decide how
to
> go
> > > > > > > forward..
> > > > > > > and then we say goodbye to the " bubbly "  keypads..  one
stroke
> > > > actions
> > > > > > > will come back to us 3030 drivers..  mac/mc
> > > > > > >
> > > > > > > Located 46 Miles due North of the Alamo
> > > > > > > and 121 Miles due South of the Western White House
> > > > > > >
> > > > > > >
> > > > > >
> > > >
> >
> ------------------------------------------------------------------------
> > > > > > >
> > > > > > > _______________________________________________
> > > > > > >
> > > > > > > Premium-Rx Mailing List
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> > > > > > > For Info: http://ml.islandnet.com/mailman/listinfo/premium-rx
> > > > > >
> > > > > >
> > > > > > --
> > > > > > Al Klase - N3FRQ
> > > > > > skywaves at bw.webex.net
> > > > > > Flemington, NJ 08822
> > > > > > Web Page:  http://www.webex.net/~skywaves/home.htm
> > > > > >
> > > > >
> > > > >
> > > > >
> > > > > _______________________________________________
> > > > >
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> > > > >
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