Problem getting NMEA from Emtac GPS sleeve

I am running an iPAQ 3650 (PPC2002) with the Transplant Computing (Emtac)
GPS sleeve. Holux GPS Viewer software works, OZIExplorer works, but in my
application no NMEA data is received. My code works fine with any type of
Garmin unit on COM1, and fine with a Holux CF GPS on COM4. The sleev is
also on COM4.
I use ReadFile( hCommPort, &char_c, 1, &dwBytesRead, NULL ) to read one
character at a time, but 0 bytes are returned. COM4 opens OK.
Is it possible that there is something unique about this receiver, such as
having to be "told" to output NMEA strings?
I guess I can look for a terminal type utility to run on the iPAQ, something
like TTY from Teletype...
Thanks in advance.
Dan

wk7414
Sun Feb 08 15:48:50 CST 2004

This is just a guess, but make sure you are raising the hardware flow
control lines. Specifically DTR/DSR and CTS/RTS. On some of these
GPSs they won't transmit without out it, but others like the TeleType
and the Pharos will transmit as long as they have power and don't dive
a hoot about the flow control.

WKM


<Dan Joerissen> wrote in message news:<u4ifNiP7DHA.2064@TK2MSFTNGP11.phx.gbl>...
> I am running an iPAQ 3650 (PPC2002) with the Transplant Computing (Emtac)
> GPS sleeve. Holux GPS Viewer software works, OZIExplorer works, but in my
> application no NMEA data is received. My code works fine with any type of
> Garmin unit on COM1, and fine with a Holux CF GPS on COM4. The sleev is
> also on COM4.
> I use ReadFile( hCommPort, &char_c, 1, &dwBytesRead, NULL ) to read one
> character at a time, but 0 bytes are returned. COM4 opens OK.
> Is it possible that there is something unique about this receiver, such as
> having to be "told" to output NMEA strings?
> I guess I can look for a terminal type utility to run on the iPAQ, something
> like TTY from Teletype...
> Thanks in advance.
> Dan

Dan
Mon Feb 09 09:54:39 CST 2004

I will look into that; presently I use XON/XOFF software flow control only,
hardware control disabled. This was because the software was originally
designed for connecting to a receiver that only had transmit/receive pins.
dcbCommPort.BaudRate = CBR_4800;
dcbCommPort.fOutxCtsFlow = FALSE;
dcbCommPort.fRtsControl = RTS_CONTROL_DISABLE;
dcbCommPort.fDtrControl = DTR_CONTROL_DISABLE;
dcbCommPort.fOutxDsrFlow = FALSE;
dcbCommPort.fOutX = TRUE;
dcbCommPort.fInX = TRUE;
dcbCommPort.ByteSize = 8;
dcbCommPort.Parity = NOPARITY;
dcbCommPort.StopBits = ONESTOPBIT;

Can I have software and hardware flow control enabled?

Regards,

"Perpetual Projects" <wk7414@hotmail.com> wrote in message
news:ff471c6b.0402081348.4bb7b1e2@posting.google.com...
> This is just a guess, but make sure you are raising the hardware flow
> control lines. Specifically DTR/DSR and CTS/RTS. On some of these
> GPSs they won't transmit without out it, but others like the TeleType
> and the Pharos will transmit as long as they have power and don't dive
> a hoot about the flow control.
>
> WKM
>
>
> <Dan Joerissen> wrote in message
news:<u4ifNiP7DHA.2064@TK2MSFTNGP11.phx.gbl>...
> > I am running an iPAQ 3650 (PPC2002) with the Transplant Computing
(Emtac)
> > GPS sleeve. Holux GPS Viewer software works, OZIExplorer works, but in
my
> > application no NMEA data is received. My code works fine with any type
of
> > Garmin unit on COM1, and fine with a Holux CF GPS on COM4. The sleev is
> > also on COM4.
> > I use ReadFile( hCommPort, &char_c, 1, &dwBytesRead, NULL ) to read one
> > character at a time, but 0 bytes are returned. COM4 opens OK.
> > Is it possible that there is something unique about this receiver, such
as
> > having to be "told" to output NMEA strings?
> > I guess I can look for a terminal type utility to run on the iPAQ,
something
> > like TTY from Teletype...
> > Thanks in advance.
> > Dan

Dan
Mon Feb 09 10:33:32 CST 2004

This works with the Emtac:
dcbCommPort.fDtrControl = DTR_CONTROL_ENABLE;
dcbCommPort.fOutX = FALSE;
dcbCommPort.fInX = FALSE;
but I'm not sure if it will work with a Garmin or similar connected by a
cable...
Regards,

"Perpetual Projects" <wk7414@hotmail.com> wrote in message
news:ff471c6b.0402081348.4bb7b1e2@posting.google.com...
> This is just a guess, but make sure you are raising the hardware flow
> control lines. Specifically DTR/DSR and CTS/RTS. On some of these
> GPSs they won't transmit without out it, but others like the TeleType
> and the Pharos will transmit as long as they have power and don't dive
> a hoot about the flow control.
>
> WKM
>
>
> <Dan Joerissen> wrote in message
news:<u4ifNiP7DHA.2064@TK2MSFTNGP11.phx.gbl>...
> > I am running an iPAQ 3650 (PPC2002) with the Transplant Computing
(Emtac)
> > GPS sleeve. Holux GPS Viewer software works, OZIExplorer works, but in
my
> > application no NMEA data is received. My code works fine with any type
of
> > Garmin unit on COM1, and fine with a Holux CF GPS on COM4. The sleev is
> > also on COM4.
> > I use ReadFile( hCommPort, &char_c, 1, &dwBytesRead, NULL ) to read one
> > character at a time, but 0 bytes are returned. COM4 opens OK.
> > Is it possible that there is something unique about this receiver, such
as
> > having to be "told" to output NMEA strings?
> > I guess I can look for a terminal type utility to run on the iPAQ,
something
> > like TTY from Teletype...
> > Thanks in advance.
> > Dan

Dick
Mon Feb 09 13:39:07 CST 2004

Hi,

As the other reply says, make sure that both DTR and RTS are high (True).
Often, GPS receivers use one or both of these controls to enable receiver
functions -- otherwise, they are in "power saving mode."

You shouldn't need XonXoff or other flow control. In my experience, most
receivers ignore flow control.

Dick

--
Richard Grier (Microsoft Visual Basic MVP)

See www.hardandsoftware.net for contact information.

Author of Visual Basic Programmer's Guide to Serial Communications, 3rd
Edition ISBN 1-890422-27-4 (391 pages) published February 2002.

Dan
Mon Feb 09 15:36:57 CST 2004

Thanks to both for the posts; DTR enabled did the trick.
Regards,