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USB 'breakout'??

S

Steve

Jan 1, 1970
0
I have a laptop with and have my GPS connected to the USB port using NMEA
183 4800 baud .. The navigation software finds this input without a problem.
However I need to have the software communicate with my Autopilot for course
correction.. This is signal is sent out in the NMEA 183 data sentence as
well but the software has no provision for me to direct it to a different
serial port.

Since the software insists on sending it data communication out on the same
USB port that is is receiving the NMEA 183 input, I need to be able to tap
the data out line from that USB port.

Is there a USB break-out box available that I can plug into the USB port
and then plug the GPS into, while leaving a connector strip that give me
access to the other lines??

I can't get any support from the software vendor because I haven't been
upgrading..

Thanks for any help.

Steve
s/v Good Intentions
 
P

Peter Bennett

Jan 1, 1970
0
I have a laptop with and have my GPS connected to the USB port using NMEA
183 4800 baud .. The navigation software finds this input without a problem.
However I need to have the software communicate with my Autopilot for course
correction.. This is signal is sent out in the NMEA 183 data sentence as
well but the software has no provision for me to direct it to a different
serial port.

Since the software insists on sending it data communication out on the same
USB port that is is receiving the NMEA 183 input, I need to be able to tap
the data out line from that USB port.

Is there a USB break-out box available that I can plug into the USB port
and then plug the GPS into, while leaving a connector strip that give me
access to the other lines??

Does the GPS connect directly to the USB port, or does it connect
through an RS-232<->USB adaptor?

If the GPS connects directly to USB, I think you're stuck.

If it really outputs serial data, and you use an RS-232<->USB adaptor
between it and the PC, you just have to do your splitting on the
RS-232 side of the adaptor.
 
S

Steve

Jan 1, 1970
0
The GPS is one of those modules, about a third the size of a pack of
cigarettes. Gets it's power from the USB port. It has a molded cable and USB
connector. No place to tap into the data out line..

Since the GPS is a talker only and the autopilot is a listener only, I
figure that neither wouldn't care if I tapped into the Data Out from the
Laptop. I need the cross track error portion of the NMEA sentence for the
autopilot.

This wouldn't be a big deal if I had purchase the Serial Port model of the
GPS, but that required a connection to the keyboard connector or something
to get the power for the module (seemed kinda hokie to me).

If the software were using a standard serial port, I could pick the NMEA
sentence off the DB9 connector data out pin.

I suppose that could be done if I opened the molded USB connector but I
thought I would look for something like a breakout box for USB..

Thanks again Peter

Steve
s/v Good Intentions
 
T

the Wiz

Jan 1, 1970
0
Steve said:
I have a laptop with and have my GPS connected to the USB port using NMEA
183 4800 baud ..

The connection is using NMEA protocol but I doubt that it's at 4800 baud - USB
doesn't run at that speed. If your device uses the standard 4 wire USB cable,
"baud" is a meaningless term.
The navigation software finds this input without a problem.
However I need to have the software communicate with my Autopilot for course
correction.. This is signal is sent out in the NMEA 183 data sentence as
well but the software has no provision for me to direct it to a different
serial port.

Since the software insists on sending it data communication out on the same
USB port that is is receiving the NMEA 183 input, I need to be able to tap
the data out line from that USB port.

Is there a USB break-out box available that I can plug into the USB port
and then plug the GPS into, while leaving a connector strip that give me
access to the other lines??

NO. USB is NOT like serial. It's a high speed 4 wire (2 power, 2 signal)
connection that does NOT provide the equivalent of a serial connection.
I can't get any support from the software vendor because I haven't been
upgrading..

Thanks for any help.

Steve
s/v Good Intentions

That "hokie" connection to the keyboard provides the power to the serial version
because the serial port is designed for communications, not for powering
devices. The USB port provides both power and communications, but it's a
totally different animal.


More about me: http://www.jecarter.com/
VB3/VB6/NSBasic Palm/C/PowerBasic source code: http://www.jecarter.com/programs.html
Drivers for Pablo graphics tablet and JamCam cameras: http://home.earthlink.net/~mwbt/
johnecarter [email protected] mindspring dot.dot com. Fix the obvious to reply by email.
 
P

Peter Bennett

Jan 1, 1970
0
The GPS is one of those modules, about a third the size of a pack of
cigarettes. Gets it's power from the USB port. It has a molded cable and USB
connector. No place to tap into the data out line..

Since the GPS is a talker only and the autopilot is a listener only, I
figure that neither wouldn't care if I tapped into the Data Out from the
Laptop. I need the cross track error portion of the NMEA sentence for the
autopilot.

This wouldn't be a big deal if I had purchase the Serial Port model of the
GPS, but that required a connection to the keyboard connector or something
to get the power for the module (seemed kinda hokie to me).

If the software were using a standard serial port, I could pick the NMEA
sentence off the DB9 connector data out pin.

I suppose that could be done if I opened the molded USB connector but I
thought I would look for something like a breakout box for USB..

Although USB does use serial data transmission, it is quite unlike
RS-232/NMEA-0183. USB uses a complex protocol, and uses differential
bi-directional communications. That is, there are not separate
transmit and receive wires in the cable - there is one pair of wires,
that carry data in different directions at different times.

It is possible that you may be able to find some serial transmit data
on the GPS side of the USB<->GPS interface chip, if the USB interface
function isn't integrated into the GPS processor.

Are you sure that your navigation program can't send the autopilot
commands out a second serial port? (either a "real" serial port, or a
USB<->serial adaptor port). My nav program (Ozi Explorer) allows me
to set the GPS i/o and autopilot output ports independently.
 
S

Steve

Jan 1, 1970
0
Ok, I think I understand what your telling me about the USB. The USB version
of this GPS module is most likely not using a serial communication since it
is independent of the NMEA 183 buss.

I guess that leaves me with the prospect of obtaining a serial GPS module or
trying to get Nautical Technologies to support my Ver 6.1 of The Cap'n
Voyager.

I'll try this question of seperate data output from The Capn on some of the
other boating forums.. I don't hold much hope for the Nautical Tech. forum.
Very crappy attitude there if your not using the latest version. Same with
their tech support..

Steve
s/v Good Intentions
 
J

Jim Large

Jan 1, 1970
0
the said:
The connection is using NMEA protocol but I doubt
that it's at 4800 baud - USB doesn't run at that
speed.

The O.P. said that the same GPS module is available
in either USB or RS-232 configurations. I'd bet
money that the the USB version has a built-in
USB <-> RS232 adapter. It's probably a single chip
in an SMT package that's no bigger than your pinkie
nail. The same companies that sell the chips will
even customize their driver software so that it
looks like a custom driver for your product rather
than a generic USB serial port driver.

There probably really *IS* async serial data
flowing at 4800 BPS. There's just no easy way to
break it out.

-- Jim L.
 
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