"What time is it?" aksed the microcontroller

Assume that we have a group of computers. Some of them are PCs and others
are small microcontroller boards of different types. Some of the PCs running
Linux and others running Windows, vxWorks or QNX. Microcontroller boards
have no operating system but some embedded program that we are going to
provide.

Our mission is "some how" synchronize their time as accurate as possible.
What we are going to debate is the following special cases;
1. All computers (PCs and controllers) are placed next to each other and
we are free to connect them together any way we want (freedom in electronics
and in sw).
2. Computers are in the same room but separated from each other with few
meters
3. Computers are in different rooms of the same building.
4. Computers are in the same campus.
5. Computers would be anyware (in the same town or city, country,
continent, on the world or near Earth orbits).

What would be your suggestions ? How to connect them together? Which sort of
HW and SW would you use ? How accurate the time sync. you would acheive
(minute, secont, milli sec, micro sec, nano sec )?

<jiang> wrote in news:40ae398e$0$31679$afc38c87@news.optusnet.com.a u:

Note: you have exceeded the polite, 3 newsgroup cross-post limit. Please
don't blast you question to every newsgroup on the planet.

> Assume that we have a group of computers. Some of them are PCs and
> others are small microcontroller boards of different types. Some of the
> PCs running Linux and others running Windows, vxWorks or QNX.
> Microcontroller boards have no operating system but some embedded
> program that we are going to provide.

Have you read the RFC for NTP? What features of NTP might you make use of
in solving your problem? Re-inventing the wheel becomes quite boring.

--
- Mark ->
--

>What would be your suggestions ? How to connect them together? Which sort of
>HW and SW would you use ? How accurate the time sync. you would acheive
>(minute, secont, milli sec, micro sec, nano sec )?

Take a look at the NTP protocol ( RFC1305 ). IMHO this covers fairly
well what you need.

Markus

jiang wrote:
>
> Assume that we have a group of computers. Some of them are PCs and others
> are small microcontroller boards of different types. Some of the PCs running
> Linux and others running Windows, vxWorks or QNX. Microcontroller boards
> have no operating system but some embedded program that we are going to
> provide.
>
> Our mission is "some how" synchronize their time as accurate as possible.
> What we are going to debate is the following special cases;
> 1. All computers (PCs and controllers) are placed next to each other and
> we are free to connect them together any way we want (freedom in electronics
> and in sw).
> 2. Computers are in the same room but separated from each other with few
> meters
> 3. Computers are in different rooms of the same building.
> 4. Computers are in the same campus.
> 5. Computers would be anyware (in the same town or city, country,
> continent, on the world or near Earth orbits).
>
> What would be your suggestions ? How to connect them together? Which sort of
> HW and SW would you use ? How accurate the time sync. you would acheive
> (minute, secont, milli sec, micro sec, nano sec )?

What class is this for? If I give you an answer, do I get the credit
for the grade in the class?

I don't know how to compensate for the time of travel of a the signal
(only an issue for the last situation), but WWV in Colorado USA
broadcasts a time signal that can be used anywhere on earth if you can
receive the signal. By synchronizing to a common source, you can sync
all your computers. Another common source is the GPS system, but again,
you have to be able to receive the signals which precludes some
locations.

--

Rick "rickman" Collins

rick.collins@XYarius.com
Ignore the reply address. To email me use the above address with the XY
removed.

Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design URL http://www.arius.com
4 King Ave 301-682-7772 Voice
Frederick, MD 21701-3110 301-682-7666 FAX

Another option is IEEE 1588, it's a time sync protocol.


"rickman" <spamgoeshere4@yahoo.com> wrote in message
news:40AE4A9C.28B57BAC@yahoo.com...
> jiang wrote:
> >
> > Assume that we have a group of computers. Some of them are PCs and
others
> > are small microcontroller boards of different types. Some of the PCs
running
> > Linux and others running Windows, vxWorks or QNX. Microcontroller boards
> > have no operating system but some embedded program that we are going to
> > provide.
> >
> > Our mission is "some how" synchronize their time as accurate as
possible.
> > What we are going to debate is the following special cases;
> > 1. All computers (PCs and controllers) are placed next to each other
and
> > we are free to connect them together any way we want (freedom in
electronics
> > and in sw).
> > 2. Computers are in the same room but separated from each other with
few
> > meters
> > 3. Computers are in different rooms of the same building.
> > 4. Computers are in the same campus.
> > 5. Computers would be anyware (in the same town or city, country,
> > continent, on the world or near Earth orbits).
> >
> > What would be your suggestions ? How to connect them together? Which
sort of
> > HW and SW would you use ? How accurate the time sync. you would acheive
> > (minute, secont, milli sec, micro sec, nano sec )?
>
> What class is this for? If I give you an answer, do I get the credit
> for the grade in the class?
>
> I don't know how to compensate for the time of travel of a the signal
> (only an issue for the last situation), but WWV in Colorado USA
> broadcasts a time signal that can be used anywhere on earth if you can
> receive the signal. By synchronizing to a common source, you can sync
> all your computers. Another common source is the GPS system, but again,
> you have to be able to receive the signals which precludes some
> locations.
>
> --
>
> Rick "rickman" Collins
>
> rick.collins@XYarius.com
> Ignore the reply address. To email me use the above address with the XY
> removed.
>
> Arius - A Signal Processing Solutions Company
> Specializing in DSP and FPGA design URL http://www.arius.com
> 4 King Ave 301-682-7772 Voice
> Frederick, MD 21701-3110 301-682-7666 FAX

<jiang> wrote:
> Assume that we have a group of computers. Some of them are PCs and others
> are small microcontroller boards of different types. Some of the PCs running
> Linux and others running Windows, vxWorks or QNX. Microcontroller boards
> have no operating system but some embedded program that we are going to
> provide.
>
> Our mission is "some how" synchronize their time as accurate as possible.

Use NTP.

<http://www.ntp.org/>
--
"cbbrowne","@","ntlug.org"
http://www3.sympatico.ca/cbbrowne/postgresql.html
First Rule of Computer Security
- Only forbid that which can be made impossible.
- Facilitate the possible.
- Have the wisdom to explain the difference.
-- Mark Miller

Assume that someone find a magical way to sync all omputers with the
accuracy you want.
How can you verify that?

<jiang> wrote in message news:<40ae398e$0$31679$afc38c87@news.optusnet.com. au>...
> Assume that we have a group of computers. Some of them are PCs and others
> are small microcontroller boards of different types. Some of the PCs running
> Linux and others running Windows, vxWorks or QNX. Microcontroller boards
> have no operating system but some embedded program that we are going to
> provide.
>
> Our mission is "some how" synchronize their time as accurate as possible.
> What we are going to debate is the following special cases;
> 1. All computers (PCs and controllers) are placed next to each other and
> we are free to connect them together any way we want (freedom in electronics
> and in sw).
> 2. Computers are in the same room but separated from each other with few
> meters
> 3. Computers are in different rooms of the same building.
> 4. Computers are in the same campus.
> 5. Computers would be anyware (in the same town or city, country,
> continent, on the world or near Earth orbits).
>
> What would be your suggestions ? How to connect them together? Which sort of
> HW and SW would you use ? How accurate the time sync. you would acheive
> (minute, secont, milli sec, micro sec, nano sec )?

Ah yes, now I remember why I fled university.

Robin

<jiang> wrote in message news:<40ae398e$0$31679$afc38c87@news.optusnet.com. au>...
> Assume that we have a group of computers. Some of them are PCs and others
> are small microcontroller boards of different types. Some of the PCs running
> Linux and others running Windows, vxWorks or QNX. Microcontroller boards
> have no operating system but some embedded program that we are going to
> provide.
>
> Our mission is "some how" synchronize their time as accurate as possible.
> What we are going to debate is the following special cases;
> 1. All computers (PCs and controllers) are placed next to each other and
> we are free to connect them together any way we want (freedom in electronics
> and in sw).
> 2. Computers are in the same room but separated from each other with few
> meters
> 3. Computers are in different rooms of the same building.
> 4. Computers are in the same campus.
> 5. Computers would be anyware (in the same town or city, country,
> continent, on the world or near Earth orbits).
>
> What would be your suggestions ? How to connect them together? Which sort of
> HW and SW would you use ? How accurate the time sync. you would acheive
> (minute, secont, milli sec, micro sec, nano sec )?

Ah yes, now I remember why I fled university.

Robin

On Mon, 24 May 2004 00:45:29 +1000, "Michael" <Michael Mich> wrote:

>Assume that someone find a magical way to sync all omputers with the
>accuracy you want.
>How can you verify that?
>

Easy ... just use Thiotimoline based components and slave them all to
a common clock source.

George
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