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'[PIC:] Using clock mechanisms (was High sleep cur'
2005\03\31@085648 by Howard Winter

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Daffy,  (just following your instructions :-)

On Tue, 29 Mar 2005 21:23:23 +1200, Jinx wrote:

{Quote hidden}

Now that's an interesting idea!  Here in the UK we have the MSF transmission on 60kHz that contains the time
and date, derived from the hyper-accurate stuff at the National Physical Laboratory.  Being a gadget-hound,
almost all of the clocks in my house are "radio controlled" from that, so I always know *exactly* how late I
am!  Most of them are digital, but I have a couple that are 3-handed.  Apart from keeping time really
accurately, they self-change in Spring and Autumn - they run at 12x usual speed to go forward an hour - I
forget if they stop for an hour or run forwards 23 to "go back" (I know they don't go backwards).

I had been wondering how to get a PIC that could keep itself spot-on in timekeeping, and your idea but using
an MSF mechanism should work fine, although obviously you have to set it accurately first.  Maplin used to
sell these, but sadly they discontinued them a few years ago, otherwise I'd be straight there to get another.  
As it is, I have to decide whether to canibalise one of my existing clocks...

Cheers,


Howard Winter
St.Albans, England


2005\03\31@090641 by Michael Rigby-Jones

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>-----Original Message-----
>From: spam_OUTpiclist-bouncesTakeThisOuTspammit.edu [.....piclist-bouncesKILLspamspam@spam@mit.edu]
>Sent: 31 March 2005 14:57
>To: Microcontroller discussion list - Public.
>Subject: Re: [PIC:] Using clock mechanisms (was High sleep
>current on 16F88)
>
>Now that's an interesting idea!  Here in the UK we have the
>MSF transmission on 60kHz that contains the time
>and date, derived from the hyper-accurate stuff at the
>National Physical Laboratory.  Being a gadget-hound,
>almost all of the clocks in my house are "radio controlled"
>from that, so I always know *exactly* how late I
>am!  Most of them are digital, but I have a couple that are
>3-handed.  Apart from keeping time really
>accurately, they self-change in Spring and Autumn - they run
>at 12x usual speed to go forward an hour - I
>forget if they stop for an hour or run forwards 23 to "go
>back" (I know they don't go backwards).

If they run at 12x speed, it would take 5 minutes to move forward an
hour, so it would take 23*5=115minutes to move forward 23hours, so it
would actually have to move forward for just over 25 hours to gain an
hour!

Regards

Mike

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2005\03\31@104823 by Alan B. Pearce

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>I had been wondering how to get a PIC that could keep itself
>spot-on in timekeeping, and your idea but using an MSF mechanism
>should work fine, although obviously you have to set it
>accurately first.  Maplin used to sell these, but sadly they
>discontinued them a few years ago, otherwise I'd be straight
>there to get another.  As it is, I have to decide whether to
>canibalise one of my existing clocks...

Me too. One idea I have had, but I think they are all too slow to actually
do it, is to feed the 60kHz straight into an input, and then have a software
phase lock loop on it, but somehow I just cannot see it working in a PIC,
unless the super clock speed of a dsPic could do it. Essentially a tuned
circuit hung on a PIC input is the way I was looking at doing it. If it is
possible to use a couple of comparators as amplifiers if need be, then so be
it.


'[PIC:] Using clock mechanisms (was High sleep cur'
2005\04\01@013046 by Peter
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On Thu, 31 Mar 2005, Alan B. Pearce wrote:

{Quote hidden}

Aren't those clocks fitted with two motors, one for each hand ? I think
they are. Both are the cheap one-coil stator with magnetic detent type.

Peter

2005\04\01@051628 by Howard Winter
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Michael,

On Thu, 31 Mar 2005 15:06:15 +0100, Michael Rigby-Jones
wrote:

>...<
> If they run at 12x speed, it would take 5 minutes to
move forward an
> hour,

True, so it then has to move on for another 5/12 minutes
to make up the difference, then another 5/144 minutes to
make up *that* difference... until the discrepancy is
less than a second, when it probably just synchronises
with the correct time.

> so it would take 23*5=115minutes to move forward
23hours, so it
> would actually have to move forward for just over 25
hours to gain an hour!

I think you mean "lose" an hour... otherwise you're
right!  I don't remember exactly what it does, so I'll
let you know in October - if I can be arsed to wait up
and watch it!  :-)

Cheers,


Howard Winter
St.Albans, Herts


2005\04\01@052203 by Howard Winter

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Alan,

On Thu, 31 Mar 2005 16:44:18 +0100, Alan B. Pearce wrote:

> One idea I have had, but I think they are all too slow to actually
> do it, is to feed the 60kHz straight into an input, and then have a software
> phase lock loop on it, but somehow I just cannot see it working in a PIC,
> unless the super clock speed of a dsPic could do it. Essentially a tuned
> circuit hung on a PIC input is the way I was looking at doing it. If it is
> possible to use a couple of comparators as amplifiers if need be, then so be
> it.

Well you could just receive the signal and decode it (the data rate is *really* low) and again Maplin used to
sell receiver and decoder kits - I think I have an uncompleted one somewhere.  I'm not sure you could use a
PLL because if I remember rightly the data is sent by interrupting the carrier, but it's a while since I
looked at this and I may be wrong.

The problem is the receiver, because the signal isn't very strong and is very susceptible to interference.  
Best to have the receiver in the loft, away from all the noisy computers and such, and feed the decoded data
down to the PIC.

Cheers,



Howard Winter
St.Albans, Herts


2005\04\01@052841 by Howard Winter

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Peter,

On Thu, 31 Mar 2005 22:08:08 +0200 (IST), Peter wrote:

> Aren't those clocks fitted with two motors, one for each hand ? I think
> they are. Both are the cheap one-coil stator with magnetic detent type.

I'm not sure (and did you mean three?).  Dammit, I'll dismantle my kitchen clock and find out, and report
back.  Its battery is reading 1.1V anyway so it's probably a good time to change it!

Cheers,


Howard Winter
St.Albans, Herts


2005\04\01@054348 by Jinx

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> Maplin used to sell these, but sadly they discontinued them a few years
> ago, otherwise I'd be straight there to get another.  As it is, I have to
> decide whether to canibalise one of my existing clocks...

Hows about July 2001

http://www.epemag.wimborne.co.uk/projects2001.html

Can't make out the IC. Once you've buffered the received signal it
wouldn't take too much to smarten things things up with a PIC. You
get quite a few hits Googling with PIC MSF 60kHz

http://www.npl.co.uk/time/msf.html

Is there an equivalent in NZ ? I'd like to have a go with it if so

2005\04\01@080325 by Howard Winter

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Jinx,

Time transmissions...

On Fri, 01 Apr 2005 22:43:42 +1200, Jinx wrote:

> Is there an equivalent in NZ ? I'd like to have a go
with it if so

The only ones I know about are from Rugby (England),
Frankfurt (Germany) and Colorado (USA).  You'd have to
ask around the scientific community to see if there is
one in NZ.

Cheers,


Howard Winter
St.Albans, England


2005\04\01@083818 by Charles Rogers

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> Jinx,
>
> Time transmissions...
>
> On Fri, 01 Apr 2005 22:43:42 +1200, Jinx wrote:
>
> > Is there an equivalent in NZ ? I'd like to have a go
> with it if so
>
> The only ones I know about are from Rugby (England),
> Frankfurt (Germany) and Colorado (USA).  You'd have to
> ask around the scientific community to see if there is
> one in NZ.
>
> Cheers,
>
>
> Howard Winter
> St.Albans, England

Came accross this thread kinda late but maby   http://www.atomtime.com  is
what you are looking for.  I use this to keep my computer clock set
with the atomic clock in Boulder. CO

CR

2005\04\01@085929 by Alan B. Pearce

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>The only ones I know about are from Rugby (England),
>Frankfurt (Germany) and Colorado (USA).  You'd have to
>ask around the scientific community to see if there is
>one in NZ.

Not aware of any 60kHz transmissions in NZ. When I worked at the DSIR the
only thing they did was a 2.5MHz continuous carrier signal for about half a
day once a week. With the break up of the DSIR as it was at that stage, I
guess they do not even do that now.

2005\04\01@092258 by Howard Winter

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Right, well having spent an interesting half hour
pulling my kitchen clock (which is an analogue, 3-hand
type that synchronises to the MSF radio signal) I can
report that the physical mechanism is a single
solenoid/ratchet driving the second hand, with the
minute and hour hands geared to that.  

This is a photo of the mechanical side:

http://www.hibernaculum.org.uk/PicPics/MSFclock.jpg

The other side of the PCB has the electronics, with all
the interesting parts having an epoxy blob over them  
:-(

Since the second hand "ticks" once a second, Jinx's idea
of pinching the drive pulse for the solenoid to feed to
a PIC would work well, as long as you can get round the
initial setting problem.  And I discovered (by reading
the instructions! :-) that when it has to go back an
hour in the Autumn, it just freezes for an hour, rather
than going forwards 23 hours (actually 11, since most
traditional clocks are inherently 12-hour).  Not ideal,
but if you can put up with a rogue hour once a year,
it's usable,  If not, then you'd have to get one of the
signal decoders that aer designed for passing the data
on to other equipment, rather than just telling people
the time.

Cheers,


Howard Winter
St.Albans, England


2005\04\01@095258 by olin_piclist

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Howard Winter wrote:
> The only ones I know about are from Rugby (England),
> Frankfurt (Germany) and Colorado (USA).

I assume you are talking about low frequency transmitters.  There is also
one in Hawaii.  There are a bunch more high frequency time transmitters
around the world, and then there's GPS everywhere.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\04\01@095955 by Alan B. Pearce

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>Well you could just receive the signal and decode it (the data
>rate is *really* low) and again Maplin used to sell receiver
>and decoder kits - I think I have an uncompleted one somewhere.
>I'm not sure you could use a PLL because if I remember rightly
>the data is sent by interrupting the carrier, but it's a while
>since I looked at this and I may be wrong.

Yeah, IIRC it is carrier off/on. But I was figuring that one could detect
PLL lock to obtain the data. Probably a long winded way to go about things,
but it was something I had considered for a long time, but never got around
to really forming ideas up. I do suspect that one would need some form of Rf
amplification to make a decent go of it, but it was one of those "I wonder
if I could ..." ideas.

I know that Temic used to have a small chip that was ideal as a receiver, to
recover the data signal. One of my colleagues used to have one here blinking
an LED with the received data, but I cannot see it at the moment. There are
probably other suitable chips as well, most likely some form of TRF system
than anything else.

2005\04\01@111331 by Dave Tweed

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Howard Winter wrote:
> The only ones I know about are from Rugby (England),
> Frankfurt (Germany) and Colorado (USA).

I found a reference to a station "HBG" on 75 kHz in Prangins, Switzerland.

olin_piclistspamKILLspamembedinc.com (Olin Lathrop) wrote:
> I assume you are talking about low frequency transmitters.
> There is also one in Hawaii.

There is???

I know about:
  WWVB - LF, Colorado (60 kHz)
  WWV  - HF, Colorado (2.5, 5, 10, 15, 20 MHz)
  WWVH - HF, Hawaii   (2.5, 5, 10, 15, 20 MHz)

> There are a bunch more high frequency time transmitters
> around the world, and then there's GPS everywhere.

I also found this:

Australia  VNG  2500, 5000, 8638, 12984, 16000 kHz  Llandilo

-- Dave Tweed

2005\04\01@112149 by Mike Hawkshaw

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> Howard Winter wrote:
> Subject: Re: [PIC:] Using clock mechanisms (was High sleep current

> Now that's an interesting idea!  Here in the UK we have the MSF
> transmission on 60kHz that contains the time
> and date, derived from the hyper-accurate stuff at the National
> Physical Laboratory.

I thought I'd heard rumours that this was going to be discontinued (which is
annoying enough for me and I only have one MSF clock) so I went and had a
look at the DTI website to see what they had to say on the matter. Here is a
link to the document, the relevant bit is project T21 starting on page 34:
http://164.36.164.20/nms/prog/new/time0306prv.pdf

But the jist is it is not certain beyond 31st March 2007...

On a brighter note, i.e. if it does continue, you might be able to use the
documents on this page:
http://www.npl.co.uk/time/msf.html to write a program to decode the data.

If it did close down in 2007 (and I had a house-full of MSF clocks, which I
don't), I would almost certainly use the above to make my own MSF
transmitter referenced to GPS, to keep them all going.

Though that would be illeagal of course.

Cheers.....Mike.






2005\04\01@115916 by olin_piclist

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Dave Tweed wrote:
>> I assume you are talking about low frequency transmitters.
>> There is also one in Hawaii.
>
> There is???

I looked it up, and my recollection was wrong.  The one in Hawaii is "short
wave" only as you said, just like WWV in Colorado.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\04\01@194231 by michael brown

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From: "Alan B. Pearce"

> Yeah, IIRC it is carrier off/on. But I was figuring that one could
detect

Alright, enough is enough.  ;-)  The carrier is never turned off, it is
reduced in power by 10dB at the start of each second.  It is then
restored to full power at either 200mS, 500mS or 800mS later.  This
conveys a binary 0, a binary 1 or a position marker respectively.  I
wonder how they do that without causing any phase/frequency distortion.

> PLL lock to obtain the data. Probably a long winded way to go about
things,
> but it was something I had considered for a long time, but never got
around
> to really forming ideas up. I do suspect that one would need some form
of Rf
> amplification to make a decent go of it, but it was one of those "I
wonder
> if I could ..." ideas.
>
> I know that Temic used to have a small chip that was ideal as a
receiver, to
> recover the data signal. One of my colleagues used to have one here
blinking
> an LED with the received data, but I cannot see it at the moment.
There are
> probably other suitable chips as well, most likely some form of TRF
system
> than anything else.
>
> --

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