Function/Reset pushbutton

On a sunny day (Fri, 12 Apr 2013 10:07:46 -0700) it happened Joerg wrote in :

together.

to the chip.

screwdriver

poking

Vladimir specidied high accuracy, your circuit is even more expensive with small tolerence caps and resistors, if it is stable at all due to chip tolerances in voltage thresholds. Takes me righ tback to the seventies.... We have advanced.

That old bicycle with dynamo and you peddling as signal generator I can imagine.

Normally FPGA code is tested in some test code setup, the only thing that bugged me about webpack is the insane error messages you sometimes get when you make some mistake, sends you in the wrong direction. Once it works it always works. You have to rely on the software for the timing specs being valid over the full temp range etc... But it is up to you how much extra margin you keep.

Cannot help you there, but it is the beginning o wanting to understand I suppose.

In spite of me tweaking him with the notion of a six-pin processor, Vladimir has a very valid point: there are some functions that you'd just as soon leave in hardware rather than software.

One may, on a design-by-design basis, review these decisions. But that doesn't mean that there isn't a valid place for what he's asking.

--
My liberal friends think I'm a conservative kook. 
My conservative friends think I'm a liberal kook. 
Why am I not happy that they have found common ground? 

Tim Wescott, Communications, Control, Circuits & Software 
http://www.wescottdesign.com

together.

to the chip.

screwdriver

poking

tolerances in voltage thresholds.

Did you forget your glasses? Quote from OP "If you press and hold the pushbutton for about 10 seconds, ..." ^^^^^^^

Now tell us, how high of an accuracy is "about"?

[...]

--
Regards, Joerg 

http://www.analogconsultants.com/

:)

--
My liberal friends think I'm a conservative kook. 
My conservative friends think I'm a liberal kook. 
Why am I not happy that they have found common ground? 

Tim Wescott, Communications, Control, Circuits & Software 
http://www.wescottdesign.com

Hardware can be more than an equal partner in such endeavors.

On a sunny day (Fri, 12 Apr 2013 11:08:01 -0700) it happened Joerg wrote in :

tolerances in voltage thresholds.

Actually he wrote: >I wonder what is the schematics for that. Should be super simple and >cheap. I would not trust R-C for 10 second delays. An oscillator with >divider logic would be bulky. Is there a specialized IC for that purpose?

Your 'solution' from 30 years back in the last centrury is exactly what he did NOT trust and want.

A simple 8 pin PIC using internal oscillator gives 2% accuracy an can be used for other things too, and is cheaper than specialized chips. If you have a FPGA on board use that.

If you cannot understand that no need to get all worked up about it :-) Just retire and grow some plants or go to a warm place in the sun where they have hula girls and large cool drinks.

tolerances in voltage thresholds.

So where is the requirement "high accuracy" in there?

[...]

--
Regards, Joerg 

http://www.analogconsultants.com/

On a sunny day (Fri, 12 Apr 2013 12:07:58 -0700) it happened Joerg wrote in :

tolerances in voltage thresholds.

Implied as obvious from 'would not trust 10 seconds RC'

10 seconds RC IS inaccurate, and the opposite of accurate, at least on my planet,

tolerances in voltage thresholds.

With an electrolytic in there you can have +80/-20% or so tolerance. With the CD4060 and regular ceramics, however, the reset could take 9sec in one case, 11sec in another. Big deal. Well, maybe on whichever planet you've landed that does make a difference for a simple reset function :-)

Didn't you call in from outer space some time ago?

--
Regards, Joerg 

http://www.analogconsultants.com/

tolerances in voltage thresholds.

Why would a 10 second time constant be any less accurate than a 10 microsecond one?

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

On a sunny day (Fri, 12 Apr 2013 13:41:18 -0700) it happened Joerg wrote in :

Bad electrolitics

Terrible.

Yes.

On my planet earth it does.

No was not me, did they ask you to join in abduction? Do not say yes, Joerg, they do horrible experiments with humans. I have seen that movie, Mars Attacks, where they put a dogs body on the head on the nice female reporter. She was scratching herself with a rear leg. Just put that receiver down when they call again, really!

Pretty standard. You need to get out more ...

For a reset? Good grief.

Aha. Then you do live on another planet.

on the nice female reporter.

Just had that, the cell phone and the lanline rang at exactly the same time. They are coming! GAAAH!!

--
Regards, Joerg 

http://www.analogconsultants.com/

on the nice female reporter.

What? The Killer Tomatoes ?>:-} ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

For timing, low leakage aluminum electrolytics are typically +/-20%.

Good for high volume designs- quite cheap you can keep the impedances reasonably low on the board by using 100uF or 220uF cap and 50-100K.

The manual is probably going to tell the user to hold it for 10 seconds even if it takes 5 seconds to reset, since many people are not all that good at judging time.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Design it so that an LED blinks upon reset activation, then tell user to hold button down until blink is observed. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

You might need to add a reset circuit for the 10F204 itself. It doesn't even have nominal BOR.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

That's a good suggestion.. usually the device goes dark after the button is held, so the user gets feedback.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Something around here does just that, but it took me a few head scratches before I remembered... programming the cable remote... blinks twice when it's done. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Why not? 10uF and a 555 (or something else that triggers near

2/3 VCC ) do you need high precision in this application ? all these parts are available as in small-ish surface mount parts the cap in 0805 (2mm x 1.2mm) the 555 in sizes down below 2mm square if your're short of space

you could possibly use a TL431 instead of the 555 it depends on on the voltage needed for reset and how much current the 431 needs on the ref pin. I've got some TL431's but I can't find them at the moment.

Oscillator with divider? 4060

reset chip? digikey has these:

--
?? 100% natural 

--- news://freenews.netfront.net/ - complaints: news@netfront.net ---