[Xastir] Help with TH-D72

[Alex Carver]

--- On Mon, 1/17/11, Harry Bloomberg wrote:

> > On Mon, 17 Jan 2011, Harry Bloomberg wrote:
> >
> >  I am able to connect to the TH-D72 using minicom
> and a USB cable.  Would
> >> it
> >> be of any value for me to manually query the
> TH-D72's TNC for GPS data?  I
> >> took a look at the Kenwood instruction set for the
> TNC and it was not
> >> obvious to me what the TNC commands would be to
> obtain GPS data to see why
> >> Xastir might think it is stale or unavailable, so
> I will need some help
> >> with
> >> the exact TNC instructions.
> >>
> >
> > I don't know what the TNC commands should be, but
> sending a Control-E
> > character from Minicom should cause the radio to dump
> the GPS string to you
> > if the TNC in the radio is set properly to capture
> it.
> >
> >
> > Thanks!  This evening I'll step through the TNC
> commands in the startup
> file for the THD7 using minicom and then issue a Control-E
> to my TH-D72 and
> see what happens.

I don't think the D72 is going to take a Control-E much like the D7 doesn't either.  The processor in the original D7 was configured to tee one single NMEA string from the GPS out onto the serial port every time it saw one come in on the GPS port.  That's the nature of the GPSHEAD command in the TNC.  You fill the GPSHEAD with a NMEA prefix (like "$GPGGA") and then every time the processor sees the prefix it pauses the output of the TNC, spits out the NMEA sentence, and then resumes the TNC data.

I once experimented with shorter prefixes on GPSHEAD but the system gets terribly confused if too many NMEA sentences match.  In one case I told the processor to look for just "$" and things fell apart from there.  There just wasn't enough throughput and horsepower to handle multiple NMEA sentences and the TNC data simultaneously out the one serial port at 9600 baud.  The processor doesn't have a problem when it's using the GPS data internally in APRS mode since it's not having to echo that data out later on, it's just parsing it.