[time-nuts] Virgin time nutter fell at the first M12+ hurdle

Chris Albertson albertson.chris at gmail.com
Wed Jun 11 22:05:43 EDT 2014


My bet is that you are telling us what you THINK you did which is not
actually what you did.  Because from what you say it should be
working.  The MT12 is not dead if it outputs a PPS signal.  Something
we can't see is wrong, a short, miscounted the pin numbers, something
like that.

If you are going to build a GPSDO then I'd guess you don't want the
GPSDO tied to something as big as a Windows PC.   You'd likely have
some kind of tiny uP inside your GPSDO.  You may as well jump in and
learn how to get the uP to talk to the MT12.   The good thing then is
you don't need the MAX3232 chip.  if you use a 3.3V uP the pins can
directly wired and you reduce a chance of error.

On Wed, Jun 11, 2014 at 4:11 PM, Stephen <si at 2si.co.uk> wrote:
> Thanks for all the replies so far. (I didn't expect them so quickly :) )
>
> I'm measuring the voltages on Pins 1 and 2 when connected to a max3232 so neither pin is floating.
>
> I have the manuals for the M12 and am aware that it's not NMEA.
> The Winoncore software isn't a terminal it is Motorola GPS software and can talk native to the M12
>
> When selecting the ID button Winoncore sends sends:@@Cj
> And i expect to see an @@Cj prefixed response string but so far nothing.
>
> I've hooked another max3232 to monitor the txd and rxd lines and there is data being sent to the M12.
> Just in case i'm being stupid i've also swapped txd and rxd over but still no response from the card.
>
> I haven't tried NTP yet.
>
> Stephen
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-- 

Chris Albertson
Redondo Beach, California


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