Debouncing....at About 1Mhz

I designed the pen-to-tablet electronics for the Kurta (now Mutoh) tablet. Though I was always impressed with the speed and accuracy we attained I never really cared for tablets. Though I almost succumbed to using a track ball many years ago.

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

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Funny!!! ;-)

But it still has an RC.

John

Gosh, where did you acquire such wit?

John

Perhaps I didn't make our procedures clear. We design, think, build, test. "Build" means a full multilayer production item, not a breadboard. "Test" means verify that everything works properly.

John

ok ok... there's an RC but it's just to make a one shot 'blip' to capture the input steady state in the D ff.

I made this circuit because I was having difficulty with tau in the original circuit.

Edge triggering should not depend on duty or repetition rate or changes in duty or repetition rate.

D from BC

On a similiar subject...

A team I was working with was developing a vehicle classifier using an overhead laser rangefinder and some other sensors. Their problem was that the laser system was not very accurate or precise, it gave the range to a vehicle with an 'error' of several inches. The laser system had actually been developed just to detect presense, not range, and range was just an unsupported feature.

So, the team went to work. Unfortunately, they were of the 'hacker' level of software developers - lets write code, and figure out how to do things later! So, after about four months, they had working code, but it was of the consistency of spaghetti, having had four different hackers working on it simultaneously.

So, the project team went to management and said "We now know how to do it, and make good determinations. Let us have another month, and we can start from scratch and build it right, from the ground up, and you will have a system that will be much more stable and dependable.

Management told them to get off their duffs and start on the next project, the system worked and that was all they needed, and that they were behind schedule anyway.

Then they fired the head of R&D!

I transfered out to the field...

Charlie

It needs an RC that doesn't transition to the cmos threshold in 100 ns, but mostly settles in 500. So maybe 250 would do it. Adding a series inductor will help a lot, make it a bit closer to a true delay and make the settling tail a lot nicer.

No, but it should be capable of meeting your specs.

John

Engineers should just say "no, it's not good enough, it's not ready, and we won't release it until it is."

Really.

John

My circuit is close to a true digital delay... play with it and observe the snap-action/hysteresis.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

Yep, but then management always has the option of then firing the design team, which in this case was a real threat. They instead just fired the manager, and broke up the team.

Charlie

[snip]

Most of the time I've had the luxury of being the "hired gun" and they wanted ME to sign off on the project. Even happened once during the Shuttle redesign. I dug in my heels and won the changes necessary.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

I have two reactions to that:

1. If they fired the team, the project would be delayed a lot more than if they negotiated a cleanup/release plan that delivered a good product. So they probably wouldn't fire them.

1. If I discovered that my management was such jerks, I'd quit before they could fire me.

John

Yup, management is easy to manage. Just set it up so that if they don't do what you want, success or failure will be their public responsibility. That works miracles.

The function of management is to provide engineering with the resources it needs to do good work, to do the admin scut work so we can design.

John

Jim...are you referring to your circuit on

? At present, it's my favorite design for now*.. (*Until I figure out JL's RC filter variants 'shoe fit's the foot' designs.)

My solution on

can use one 3.5nS comparator for an output edge delay of only 3.5nS. This makes it one of the fastest/tightest solutions. But I dunno...it's got a 'too good to be true' look to it.. I'm worried a built circuit might find a way to oscillate. So..I'm dodging that pita analysis for now and will save it for the next iteration.

For now.. Dff based designs look less stressful. :)

D from BC

[snip]

Yes.

Same here. Build it and see ;-)

Certainly ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

Yeah, but they had the 'product' that they needed to fulfil a contract requirement, even if it was a piece of cr*p, and that was all they really cared about. They kept most of the team on, and made one of the senior folk the new 'manager' (on a very short leash!) for the 9 months they spent keeping the team on until the contract was ready to finish. I transfered to the actual project from the R&D team to get back to CA and out of Omaha, and was laid off a year later (also referred to as my Year in Hell...)

Should have quit, but they held this big carrot of bonuses if I stayed out the project. Then, just before Christmas, they had a special meeting where they handed out the bonus checks. Imagine my reaction when at the end of the meeting, I was the only one that didn't get a check! I should have sued them, but just wanted out so bad that I just left...

Charlie

Well, Charlie, You know what the final end-of-project meeting is called, "Punishment of the innocent" ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

Well, I have to admit that by that time the last thing I felt was 'innocent!' That project had so much afro-engineering that it was amazing that it ran long enough to get through the acceptance trials.

Charlie