One Second Pulse-Width, Once Per Hour

Jim Thompson · Apr 2, 2004

On Fri, 02 Apr 2004 04:08:30 GMT, "Tom Del Rosso"
<tdnews01@att.net.invalid> wrote:

In news:8e1p60tkc3c5jdcm38ld96pge3s14gs2ef@4ax.com,
Jim Thompson typed:

Do you remember the VetaVitaVegamin skit that Lucille Ball did eons
ago ?

VitaMeataVegamin

It has vitamins and meat and vegetables, and apparently some liquor.
^^^^^^^^^^^^^^^^^^^^^^

480)460-2350 | |
| E-mail Address at Website Fax

Tam/WB2TT · Apr 2, 2004

Whichever way you do it, you need a power on reset circuit so the thing
doesn't require an hour to straighten itself out.

Tam

John Fields · Apr 2, 2004

On Fri, 2 Apr 2004 15:42:15 -0500, "Tam/WB2TT" <t-tammaru@c0mca$t.net>
wrote:

Whichever way you do it, you need a power on reset circuit so the thing
doesn't require an hour to straighten itself out.
---

Yes. See my circuit posted on alt.binaries.schematics.electronic.

--
John Fields

John Fields · Apr 2, 2004

On Fri, 02 Apr 2004 22:52:19 GMT, maxfoo
<maxfooHeadFromButt@punkass.com> wrote:

On Thu, 01 Apr 2004 18:32:05 +1000, Al Borowski
aj.borowski@erasethis.student.qut.edu.au> wrote:

Jim Thompson wrote:
I can't locate the original post, but there was a request for a way to
generate a one second pulse-width, occurring once per hour. I
happened on to a similar circuit in the 74HC4040 data sheet and
modified it for the required pulse-width.

This is just *begging* for a low end PIC

This would take literally 5 mins to code (if that) and be very accurate.
Only problem is if the OP doesn't have a programmer. If he does, heck,
I'll even code it.

Al

yup, pic12c508 eight pin dip internal 4mhz clk, less than a buck each.
But the old timers'll never go for it...

---
Maybe not, since it might depend on the accuracy of the internal clock
oscillator. What is it?

--
John Fields

Jim Thompson · Apr 2, 2004

On Fri, 02 Apr 2004 22:52:19 GMT, maxfoo
<maxfooHeadFromButt@punkass.com> wrote:

On Thu, 01 Apr 2004 18:32:05 +1000, Al Borowski
aj.borowski@erasethis.student.qut.edu.au> wrote:

Jim Thompson wrote:
I can't locate the original post, but there was a request for a way to
generate a one second pulse-width, occurring once per hour. I
happened on to a similar circuit in the 74HC4040 data sheet and
modified it for the required pulse-width.

This is just *begging* for a low end PIC

This would take literally 5 mins to code (if that) and be very accurate.
Only problem is if the OP doesn't have a programmer. If he does, heck,
I'll even code it.

Al

yup, pic12c508 eight pin dip internal 4mhz clk, less than a buck each.
But the old timers'll never go for it...

I don't have any in my junk box. CK722's, though ;-)

But I'm open to education... what do I need to buy to learn this
"new-fangled" thingy... is it anything like a tooob ?

480)460-2350 | |
| E-mail Address at Website Fax

Jim Thompson · Apr 2, 2004

On Fri, 02 Apr 2004 23:36:36 GMT, maxfoo
<maxfooHeadFromButt@punkass.com> wrote:

On Fri, 02 Apr 2004 23:17:51 GMT, jfields@austininstruments.com (John Fields)
wrote:

On Fri, 02 Apr 2004 22:52:19 GMT, maxfoo
maxfooHeadFromButt@punkass.com> wrote:

On Thu, 01 Apr 2004 18:32:05 +1000, Al Borowski
aj.borowski@erasethis.student.qut.edu.au> wrote:
[snip]
This is just *begging* for a low end PIC

This would take literally 5 mins to code (if that) and be very accurate.
Only problem is if the OP doesn't have a programmer. If he does, heck,
I'll even code it.

Al

yup, pic12c508 eight pin dip internal 4mhz clk, less than a buck each.
But the old timers'll never go for it...

---
Maybe not, since it might depend on the accuracy of the internal clock
oscillator. What is it?

Its an internal 4 MHz RC oscillator with programmable calibration.
here is the link to the datasheet.

http://www.microchip.com/1010/pline/picmicro/category/digictrl/8kbytes/devices/12c508a/index.htm

[snip]

Thanks for the reminder. The existing R/C oscillator in the PICs is
not very stable.

I designed a replacement that will be in future PICs. It's similar to
"CMOS-Osc-NoClip.pdf" on the S.E.D/Schematics page of my website,
except that the R-tap approach isn't used, since that node does not
have an external connection.

But my approach still isn't anything near what you can get with a
crystal.

...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

John Fields · Apr 2, 2004

On Fri, 02 Apr 2004 23:36:36 GMT, maxfoo
<maxfooHeadFromButt@punkass.com> wrote:

On Fri, 02 Apr 2004 23:17:51 GMT, jfields@austininstruments.com (John Fields)
wrote:

On Fri, 02 Apr 2004 22:52:19 GMT, maxfoo
maxfooHeadFromButt@punkass.com> wrote:

On Thu, 01 Apr 2004 18:32:05 +1000, Al Borowski
aj.borowski@erasethis.student.qut.edu.au> wrote:

Jim Thompson wrote:
I can't locate the original post, but there was a request for a way to
generate a one second pulse-width, occurring once per hour. I
happened on to a similar circuit in the 74HC4040 data sheet and
modified it for the required pulse-width.

This is just *begging* for a low end PIC

This would take literally 5 mins to code (if that) and be very accurate.
Only problem is if the OP doesn't have a programmer. If he does, heck,
I'll even code it.

Al

yup, pic12c508 eight pin dip internal 4mhz clk, less than a buck each.
But the old timers'll never go for it...

---
Maybe not, since it might depend on the accuracy of the internal clock
oscillator. What is it?

Its an internal 4 MHz RC oscillator with programmable calibration.
here is the link to the datasheet.

http://www.microchip.com/1010/pline/picmicro/category/digictrl/8kbytes/devices/12c508a/index.htm

---
Since I'm an "old timer" and I don't have all that much time left to
go slogging through Microchip's data sheets, I thought that since you
seem to be familiar with their products perhaps you might be good
enough to summarize the maximum accuracy attainable???

--
John Fields

Spehro Pefhany · Apr 2, 2004

On Fri, 02 Apr 2004 16:20:33 -0700, the renowned Jim Thompson
<thegreatone@example.com> wrote:

On Fri, 02 Apr 2004 22:52:19 GMT, maxfoo
maxfooHeadFromButt@punkass.com> wrote:

On Thu, 01 Apr 2004 18:32:05 +1000, Al Borowski
aj.borowski@erasethis.student.qut.edu.au> wrote:

Jim Thompson wrote:
I can't locate the original post, but there was a request for a way to
generate a one second pulse-width, occurring once per hour. I
happened on to a similar circuit in the 74HC4040 data sheet and
modified it for the required pulse-width.

This is just *begging* for a low end PIC

This would take literally 5 mins to code (if that) and be very accurate.
Only problem is if the OP doesn't have a programmer. If he does, heck,
I'll even code it.

Al

yup, pic12c508 eight pin dip internal 4mhz clk, less than a buck each.
But the old timers'll never go for it...

I don't have any in my junk box. CK722's, though ;-)

But I'm open to education... what do I need to buy to learn this
"new-fangled" thingy... is it anything like a tooob ?

...Jim Thompson

Octal base if you like. ;-)

Unadjusted accuracy is +/-7% over temperature @5V Vdd, which isn't too
bad, but there are better ones.

The similar 8-pin PIC12F629/75 is within +/-2% over Vdd and
temperature, and within +/-1% at 3.5V and 25°C. Of course that's
because it's calibrated at the factory. $1.11 in 100's.

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

Spehro Pefhany · Apr 2, 2004

On Fri, 02 Apr 2004 17:02:14 -0700, the renowned Jim Thompson
<thegreatone@example.com> wrote:

Thanks for the reminder. The existing R/C oscillator in the PICs is
not very stable.

I designed a replacement that will be in future PICs. It's similar to
"CMOS-Osc-NoClip.pdf" on the S.E.D/Schematics page of my website,
except that the R-tap approach isn't used, since that node does not
have an external connection.

But my approach still isn't anything near what you can get with a
crystal.

Even a resonator is pretty good compared to anything made with
ordinary RC components. +/-0.5% initial tolerance and very low drift.
Cheap; only one added part.

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

Winfield Hill · Apr 3, 2004

Jim Thompson wrote...

I designed a replacement that will be in future PICs. It's similar
to "CMOS-Osc-NoClip.pdf" on the S.E.D/Schematics page of my website,
except that the R-tap approach isn't used, since that node does not
have an external connection.

I imagine you modified the input-protection circuit to allow beyond-
the-rail swings, thereby stopping any undesired input-current draw?
Very nice, this reduces any errors from power-supply voltage drift,
etc. Nevertheless, surely Microchip's in-circuit post-calibration
approach is still necessary, given the usual poor capacitor accuracy?

Thanks,
- Win

whill_at_picovolt-dot-com

Winfield Hill · Apr 3, 2004

John Fields wrote...

Since I'm an "old timer" and I don't have all that much time left to
go slogging through Microchip's data sheets, I thought that since you
seem to be familiar with their products perhaps you might be good
enough to summarize the maximum accuracy attainable???

Their in-circuit calibration scheme talks about 1% overall accuracy.

Thanks,
- Win

whill_at_picovolt-dot-com

Jim Thompson · Apr 3, 2004

On 2 Apr 2004 17:27:05 -0800, Winfield Hill
<Winfield_member@newsguy.com> wrote:

Jim Thompson wrote...

I designed a replacement that will be in future PICs. It's similar
to "CMOS-Osc-NoClip.pdf" on the S.E.D/Schematics page of my website,
except that the R-tap approach isn't used, since that node does not
have an external connection.

I imagine you modified the input-protection circuit to allow beyond-
the-rail swings, thereby stopping any undesired input-current draw?
Very nice, this reduces any errors from power-supply voltage drift,
etc. Nevertheless, surely Microchip's in-circuit post-calibration
approach is still necessary, given the usual poor capacitor accuracy?

Thanks,
- Win

whill_at_picovolt-dot-com

480)460-2350 | |
| E-mail Address at Website Fax

Al Borowski · Apr 3, 2004

I designed a replacement that will be in future PICs. It's similar to
"CMOS-Osc-NoClip.pdf" on the S.E.D/Schematics page of my website,
except that the R-tap approach isn't used, since that node does not
have an external connection.

Is there any large company you *haven't* designed for?

Al

Winfield Hill · Apr 3, 2004

Jim Thompson wrote...

The main inaccuracy is poly R's, NOT the (fairly) accurate C's.

So, how do you solve that? External R? Or is it back to
requiring a factory cal? What *uncalibrated* accuracy are
we talking about here, 1% 2% 5%?

Thanks,
- Win

whill_at_picovolt-dot-com

John Fields · Apr 3, 2004

On Sat, 03 Apr 2004 18:08:07 +1000, Al Borowski
<aj.borowski@erasethis.student.qut.edu.au> wrote:

I designed a replacement that will be in future PICs. It's similar to
"CMOS-Osc-NoClip.pdf" on the S.E.D/Schematics page of my website,
except that the R-tap approach isn't used, since that node does not
have an external connection.

Is there any large company you *haven't* designed for?

---
Austin Instruments...

--
John Fields

Spehro Pefhany · Apr 3, 2004

On 3 Apr 2004 03:23:47 -0800, the renowned Winfield Hill
<Winfield_member@newsguy.com> wrote:

Jim Thompson wrote...

The main inaccuracy is poly R's, NOT the (fairly) accurate C's.

So, how do you solve that? External R? Or is it back to
requiring a factory cal? What *uncalibrated* accuracy are
we talking about here, 1% 2% 5%?

I have 20-30% in mind for unadjusted resistor accuracy.. don't know if
that's still true, have things improved, Jim? Some of the specialist
linear IC makers have much more accurate resistors but I suspect they
are trimmed metal film.

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

John Fields · Apr 3, 2004

On Sat, 03 Apr 2004 13:41:36 GMT, maxfoo
<maxfooHeadFromButt@punkass.com> wrote:

On Sat, 03 Apr 2004 00:04:43 GMT, jfields@austininstruments.com (John Fields)
wrote:

Since I'm an "old timer" and I don't have all that much time left to
go slogging through Microchip's data sheets, I thought that since you
seem to be familiar with their products perhaps you might be good
enough to summarize the maximum accuracy attainable???

Sheesh...You can lead an old timer to water, but you can't make em drink.
(The water that is, tequila is an other story)

---
Translation: "I don't have a fucking clue."

--
John Fields

Jim Thompson · Apr 3, 2004

On Sat, 03 Apr 2004 13:34:04 GMT, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

On 3 Apr 2004 03:23:47 -0800, the renowned Winfield Hill
Winfield_member@newsguy.com> wrote:

Jim Thompson wrote...

The main inaccuracy is poly R's, NOT the (fairly) accurate C's.

So, how do you solve that? External R? Or is it back to
requiring a factory cal? What *uncalibrated* accuracy are
we talking about here, 1% 2% 5%?

I have 20-30% in mind for unadjusted resistor accuracy.. don't know if
that's still true, have things improved, Jim? Some of the specialist
linear IC makers have much more accurate resistors but I suspect they
are trimmed metal film.

Best regards,
Spehro Pefhany

480)460-2350 | |
| E-mail Address at Website Fax

Jim Thompson · Apr 3, 2004

On Sat, 03 Apr 2004 18:08:07 +1000, Al Borowski
<aj.borowski@erasethis.student.qut.edu.au> wrote:

I designed a replacement that will be in future PICs. It's similar to
"CMOS-Osc-NoClip.pdf" on the S.E.D/Schematics page of my website,
except that the R-tap approach isn't used, since that node does not
have an external connection.

Is there any large company you *haven't* designed for?

Al

480)460-2350 | |
| E-mail Address at Website Fax

Rich Grise · Apr 4, 2004

"maxfoo" <maxfooHeadFromButt@punkass.com> wrote in message

On Thu, 01 Apr 2004 18:32:05 +1000, Al Borowski
aj.borowski@erasethis.student.qut.edu.au> wrote:

Jim Thompson wrote:
I can't locate the original post, but there was a request for a way to
generate a one second pulse-width, occurring once per hour. I
happened on to a similar circuit in the 74HC4040 data sheet and
modified it for the required pulse-width.

This is just *begging* for a low end PIC

This would take literally 5 mins to code (if that) and be very accurate.
Only problem is if the OP doesn't have a programmer. If he does, heck,
I'll even code it.

Al

yup, pic12c508 eight pin dip internal 4mhz clk, less than a buck each.
But the old timers'll never go for it...

Yeah, but what does the development system cost? I can't just

buy a PIC chip and plug it in, now, can I? I have to have
_some_ way of getting this hypothetical 5-minute program into
the chip, right?

So, what's that going to cost?

Thanks,
Rich

One Second Pulse-Width, Once Per Hour

Jim Thompson

Guest

Tam/WB2TT

Guest

John Fields

Guest

John Fields

Guest

Jim Thompson

Guest

Jim Thompson

Guest

John Fields

Guest

Spehro Pefhany

Guest

Spehro Pefhany

Guest

Winfield Hill

Guest

Winfield Hill

Guest

Jim Thompson

Guest

Al Borowski

Guest

Winfield Hill

Guest

John Fields

Guest

Spehro Pefhany

Guest

John Fields

Guest

Jim Thompson

Guest

Jim Thompson

Guest

Rich Grise

Guest

Log in

Welcome to EDABoard.com

Sponsor