Features of a Precision Clock?
Hi:
I've got the Precision Clock to work and have some questions about the
priority of the features. As it is now the clock allows user selection
of the input frequency at power up that determines the instruction clock
for the PIC micro controller. The choices are 2.5, 5, 10 or 20 Mhz.
The clock displays on line one HH:MM:SS and on line two Day of Week,
YYYY, Mon, Day of Month. The leap year testing uses the 4, 100 and 400
year rules and so you can determine the day of the week for any Georgian
calendar (1583 onwards) date.
Setting is by means of 4 buttons, Right, Left, Increment, Decrement.
This is very intuitive and quick. During setting the clock continues to
keep time. Also a new data field to the right of the seconds appears as
4 hex digits to allow moving the LED/1 PPS output pulse in 1 ms steps.
If the input frequency fails then all the fields that can blink do blink
and the clock stops. Pressing and holding Right or Left for a few
seconds clears the blinking and restarts the clock using the input
frequency that was selected at power up.
For more see:
http://www.pacificsites.com/~brooke/PRC68COM.shtml#PC3
Now for the possible next features to be added. It would be nice to get
some feel for how important they are:
(1) Synchronize the 1 PPS output rising edge to be near a 1 PPS input
pulse on a one time basis (the 1 PPS edge will have an error of a few
instruction cycles which are each 4/Fin long). If this was done the
manual setting would be removed.
(2) Add another mode of operation where the clock runs on it's internal
RC oscillator and the timing is determined by an external 1 PPS that
needs to always be connected.
(3) Add a backup Real Time Clock with it's own coin cell battery to
allow using the clock in a portable application and allow the clock to
be shipped while running. The chip has a 0.1 ppm aging trim capability
and there could be a provision to automatically trim it when one of the
above precision input frequencies is applied for maybe a day. Then when
the input frequency is disconnected the clock would continue to tell the
time. There are also many options for alarms.
(4) Other displays such as fractional Julian Day number, fractional
Modified Julian Day number. sidereal time, or ???
I don't think there's enough memory for all of the above, probably only
one or two of them so I'm hoping to get some input on the priorities.
Have Fun,
Brooke Clarke
--
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
On receipt of Bulletin C, can you arm this clock to display the upcoming
leap second? That's a feature that I would desire.
Brooke Clarke wrote:
Hi:
I've got the Precision Clock to work and have some questions about the
priority of the features. As it is now the clock allows user selection
of the input frequency at power up that determines the instruction clock
for the PIC micro controller. The choices are 2.5, 5, 10 or 20 Mhz.
The clock displays on line one HH:MM:SS and on line two Day of Week,
YYYY, Mon, Day of Month. The leap year testing uses the 4, 100 and 400
year rules and so you can determine the day of the week for any Georgian
calendar (1583 onwards) date.
Setting is by means of 4 buttons, Right, Left, Increment, Decrement.
This is very intuitive and quick. During setting the clock continues to
keep time. Also a new data field to the right of the seconds appears as
4 hex digits to allow moving the LED/1 PPS output pulse in 1 ms steps.
If the input frequency fails then all the fields that can blink do blink
and the clock stops. Pressing and holding Right or Left for a few
seconds clears the blinking and restarts the clock using the input
frequency that was selected at power up.
For more see:
http://www.pacificsites.com/~brooke/PRC68COM.shtml#PC3
Now for the possible next features to be added. It would be nice to get
some feel for how important they are:
(1) Synchronize the 1 PPS output rising edge to be near a 1 PPS input
pulse on a one time basis (the 1 PPS edge will have an error of a few
instruction cycles which are each 4/Fin long). If this was done the
manual setting would be removed.
(2) Add another mode of operation where the clock runs on it's internal
RC oscillator and the timing is determined by an external 1 PPS that
needs to always be connected.
(3) Add a backup Real Time Clock with it's own coin cell battery to
allow using the clock in a portable application and allow the clock to
be shipped while running. The chip has a 0.1 ppm aging trim capability
and there could be a provision to automatically trim it when one of the
above precision input frequencies is applied for maybe a day. Then when
the input frequency is disconnected the clock would continue to tell the
time. There are also many options for alarms.
(4) Other displays such as fractional Julian Day number, fractional
Modified Julian Day number. sidereal time, or ???
I don't think there's enough memory for all of the above, probably only
one or two of them so I'm hoping to get some input on the priorities.
Have Fun,
Brooke Clarke
--
James Maynard
Salem, Oregon, USA
Hi James:
Can you point me to an example Bulletin C?
Have Fun,
Brooke Clarke
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
James Maynard wrote:
On receipt of Bulletin C, can you arm this clock to display the upcoming
leap second? That's a feature that I would desire.
Brooke Clarke wrote:
Hi:
I've got the Precision Clock to work and have some questions about the
priority of the features. As it is now the clock allows user selection
of the input frequency at power up that determines the instruction clock
for the PIC micro controller. The choices are 2.5, 5, 10 or 20 Mhz.
The clock displays on line one HH:MM:SS and on line two Day of Week,
YYYY, Mon, Day of Month. The leap year testing uses the 4, 100 and 400
year rules and so you can determine the day of the week for any Georgian
calendar (1583 onwards) date.
Setting is by means of 4 buttons, Right, Left, Increment, Decrement.
This is very intuitive and quick. During setting the clock continues to
keep time. Also a new data field to the right of the seconds appears as
4 hex digits to allow moving the LED/1 PPS output pulse in 1 ms steps.
If the input frequency fails then all the fields that can blink do blink
and the clock stops. Pressing and holding Right or Left for a few
seconds clears the blinking and restarts the clock using the input
frequency that was selected at power up.
For more see:
http://www.pacificsites.com/~brooke/PRC68COM.shtml#PC3
Now for the possible next features to be added. It would be nice to get
some feel for how important they are:
(1) Synchronize the 1 PPS output rising edge to be near a 1 PPS input
pulse on a one time basis (the 1 PPS edge will have an error of a few
instruction cycles which are each 4/Fin long). If this was done the
manual setting would be removed.
(2) Add another mode of operation where the clock runs on it's internal
RC oscillator and the timing is determined by an external 1 PPS that
needs to always be connected.
(3) Add a backup Real Time Clock with it's own coin cell battery to
allow using the clock in a portable application and allow the clock to
be shipped while running. The chip has a 0.1 ppm aging trim capability
and there could be a provision to automatically trim it when one of the
above precision input frequencies is applied for maybe a day. Then when
the input frequency is disconnected the clock would continue to tell the
time. There are also many options for alarms.
(4) Other displays such as fractional Julian Day number, fractional
Modified Julian Day number. sidereal time, or ???
I don't think there's enough memory for all of the above, probably only
one or two of them so I'm hoping to get some input on the priorities.
Have Fun,
Brooke Clarke
Brooke Clarke wrote:
Hi James:
Can you point me to an example Bulletin C?
Have Fun,
Brooke Clarke
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
Here's the most recent one, downloaded from the IERS Web site:
INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE (IERS)
SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE
SERVICE DE LA ROTATION TERRESTRE
OBSERVATOIRE DE PARIS
61, Av. de l'Observatoire 75014 PARIS (France)
Tel. : 33 (0) 1 40 51 22 26
FAX : 33 (0) 1 40 51 22 91
Internet : services.iers@obspm.fr
Paris, 19 July 2006
Bulletin C 32
To authorities
esponsible
for the measurement and
distribution of time
INFORMATION ON UTC - TAI
NO positive leap second will be introduced at the end of December 2006.
The difference between Coordinated Universal Time UTC and the
International Atomic Time TAI is :
from 2006 January 1, 0h UTC, until further notice : UTC-TAI = -33 s
Leap seconds can be introduced in UTC at the end of the months of
December or June, depending on the evolution of UT1-TAI. Bulletin C is
mailed every six months, either to announce a time step in UTC, or to
confirm that there will be no time step at the next possible date.
Daniel GAMBIS
Director
Earth Orientation Center of IERS
Observatoire de Paris, France
Good to hear that this project is coming along nicely!
(1) Synchronize the 1 PPS output rising edge to be near a 1 PPS input
pulse on a one time basis (the 1 PPS edge will have an error of a few
instruction cycles which are each 4/Fin long). If this was done the
manual setting would be removed.
Would this be used to sync a 10 MHz osc to a 1 PPS from a GPS?
If yes, then definately.
Another idea along these lines: make the clock able to set it's time
from a GPS (Oncore would be my choice).
(2) Add another mode of operation where the clock runs on it's internal
RC oscillator and the timing is determined by an external 1 PPS that
needs to always be connected.
Not a bad idea, but #3 seems like a better idea:
(3) Add a backup Real Time Clock with it's own coin cell battery to
allow using the clock in a portable application and allow the clock to
be shipped while running. The chip has a 0.1 ppm aging trim capability
and there could be a provision to automatically trim it when one of the
above precision input frequencies is applied for maybe a day. Then when
the input frequency is disconnected the clock would continue to tell the
time. There are also many options for alarms.
Yes! Yes! Yes! An alarm would be great. "Snooze" would make it even better!
Although, something I could hook a relay up to would be MUCH better than
a buzzer. This would then replace my bedside alarm clock.
(4) Other displays such as fractional Julian Day number, fractional
Modified Julian Day number. sidereal time, or ???
IMHO, features like an alarm, which would make the clock much more
"acceptable" to "significant others" would make it easier to sell (and buy)
than alternate date displays.
cheers,
glenn
How about a version that works from the 50/60 Hz power frequency
with a 1 PPS output and internal micro clock oscillator?
Great for watching the power grid lose time and regain it as the
power generated vs. consumed balance varies. If the power line
PPS lags behind at an increasing rate, it's time to turn off the
air conditioner and run all those clock ovens on battery before
the under-frequency relays start cascading.
Of course, you need the precision version for comparison.
Does anybody in this group look at power line frequency drift?
Bill Hawkins
Does anybody in this group look at power line frequency drift?
On Fri, Oct 06, 2006 at 03:17:14PM -0500, Bill Hawkins wrote:
Does anybody in this group look at power line frequency drift?
Not currently, but I did so last year during a few months:
http://wwwhome.cs.utwente.nl/~ptdeboer/misc/mains.html
Pieter-Tjerk (PA3FWM)
Hi Bill:
On the "to do" list is a version based on Richard McCorkle's RS232 Time
Interval counter.
For a minimum cost version a different PIC is needed than the 16F88 used
in the Current Version (PC4).
Once the TI counter is part of the clock then all kinds of neat things
can be done. I'll keep in the looking at the mains.
In the PC4 there's a software TI counter good to 1 ms that can be used
to trim the Real Time Clock chip.
Have Fun,
Brooke Clarke
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
Bill Hawkins wrote:
How about a version that works from the 50/60 Hz power frequency
with a 1 PPS output and internal micro clock oscillator?
Great for watching the power grid lose time and regain it as the
power generated vs. consumed balance varies. If the power line
PPS lags behind at an increasing rate, it's time to turn off the
air conditioner and run all those clock ovens on battery before
the under-frequency relays start cascading.
Of course, you need the precision version for comparison.
Does anybody in this group look at power line frequency drift?
Bill Hawkins
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