Yes, Miguel, someone did mention an NTP synched clock some time back,
and
I thought it might be a fun project. Based on an Arduino board IIRC?
Although I don't think it had Wi-Fi by default....
I have it running at the moment. Have to build a case tough. See
attached
picture.
It looks very smart!
It syncs at the 9th, 19th, 29th, ... second mark from a local GPS based
NTP
server.
On every sync, the timestamp returned from the NTP server is on the 6 ms
mark this means that the local clock of the Arduino drifts a lot.
6 ms per 10 s. Outside the 500 ppm allowed for NTP! <G>
I am
installing a realtime clock (Chronodot) this weekend that has an
accuracy
of +/- 3.5 ppm from -40C to 85C (I read somewhere that between 0 and 40C
it
is 2 ppm). This RTC can output a square wave signal at 1 Hz and Arduino
can
read that and use it to update the display at the exact second mark.
With the RTC and synching every 10 minutes (9th, 19th, 29th, 39th, 49th
and
59th of every hour) I expect a maximum error of 1.2 ms (based on 2 ppm).
My
eyes can't read that :-)
Nor mine! On my PC, the radio pips, and the hands on the analogue clock I
wrote, appear to be precisely in sync, but I expect that means within a
few tens of milliseconds.
A neat feature I added is that when the clock can't synch it won't show
a
time. It will show -- : --.
Shouldn't that be the classic video recorder display? A flashing 00:00 or
whatever?
I also have code that enables the user to telnet to the clock's IP
address
and change its setting which are saved in the Arduino EEPROM.
If you are interested in a parts list and even the code I can send it to
you next week as soon as I add the RTC
The most interesting part is that buying a clock from Inova (
http://www.inovasolutions.com/network-clocks/products/digital-network-clock.htm)
would cost be 5 times more and it would not be as accurate as this one.
Cheers,
Miguel
Yes, I would be interested, but others might as well, so perhaps put it up
on the Web somewhere?
Cheers,
David
--
SatSignal software - quality software written to your requirements
Web: http://www.satsignal.eu
Email: [email protected]
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