[time-nuts] TruePosition and Arduino Progress
kd5byb at gmail.com
Sun May 21 09:45:19 EDT 2017
Good morning all,
A quick update for those interested on my Arduino code development for
the TruePosition boards. I've got Arduino code together than can read
in the serial stream, parse it, and display time, date, number of
satellites, and TFOM on a 2x16 LCD display. It does not do multiple
screens, handle survey, or display lat/long yet.
What I'm having issues with is handling the 1 PPS. Ideally, I want to
use the 1PPS signal to trigger the display update. IE:
getSerialString() // uses serial.available to pull in the serial data
parser() // this parses the data
wait for 1PPS tick to go high
if there has been a clock message, updateDispay() // update the display
This works great when there is a just a clock message. But when there
is a clock message, an extstatus message, and a status message, it seems
like it is still parsing when the 1PPS tick comes in...so it will
display seconds as follows: 30, 31, 33, 34, 35, 36, 37, 39, etc...
(If I don't wait for the 1PPS tick, it seems that my clock is one second
fast. I say "seems" to be fast, as the time agrees with an NTP clock on
one computer, but seems a half second slow per GPSCon's time display on
the Z3801. I think I need to put up the antenna and check against WWV.)
I've got one of those cheap little USB logic analyzers on order to
figure out how much time elapses between the clock, extstatus, status,
and 1PPS tick. I may need something faster than an Arduino Uno to do this.
I'm sure there is a way to do this with an interrupt...but I couldn't
make that work yesterday. More to follow.
thanks much and 73,
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