Hi If you are doing this from scratch today, would you go IRIG or would you go RS-485 for a wall clock? Both will drive more cable than you are likely to have in a house. Both are reasonably noise immune. With RS-485 there's less to do. It's a serial stream like any other bunch of "stuff" into a UART.
Some math: YYMMDDHHMMSSCR = 13 ASCII characters. With one check byte it would be 14. A baud rate of 115.4K isn't stretching things on RS-485 or on most UART's these days. Sent it at 7N1 you have 9 bits per character, 126 bits in the message. Message takes a bit over 1 ms. Time it to anywhere in the string and the clock should be within <+/- 2 ms. That's better than I can see on a clock. Better yet, time it to the first (or last) character in the string. More or less a 10X improvement. You could also drop the year / month / day if the clock isn't going to use them. Take any of the Arduino (or what ever) LED display boards and drive them with something cheap. I doubt the "clock" end plus the drivers would be over $30. I suspect IRIG would cost a bit more once you got it all worked out. Bob On May 27, 2013, at 11:03 AM, Chris Albertson <[email protected]> wrote: > I've seen LLCD computer monitors used as clocks. Seems this would be > the perfect use for a Rasbury Pi. and a cheap monitor. $100 or maybe a > low-end Android tablet. > > The way it is more commonly done is you have you computer that is > using NTP produce an IRIG time code. Then there are any number of > commercial clocks and large digital LED displays that will use IRIG. > IRIG displays are not cheap but they sure are easy to find. > > On Mon, May 27, 2013 at 6:29 AM, Miguel Barbosa Gonçalves <[email protected]> wrote: >> Hi! >> >> I was wondering if anyone knows about a not so expensive wall digital clock >> that gets its time from an NTP server... >> >> TIA, >> Miguel >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > > > -- > > Chris Albertson > Redondo Beach, California > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
