| Author |
Garmin GPS18 (USB)
|
|
| BigAl.NZ@gmail.com 2006-03-04, 5:48 pm |
| Hi Guys,
We recently got a Garmin GPS18 which we are using with GPS Gate to get
the output to Virtual Serial Port.
This GPS claims to be 5Hz update, yet when I connected to the virtual
com port via Hyper Terminal the updates seem to only be coming about 2
every second.
Anyone know whats going on here?
-Al
| |
| Bruce E. Stemplewski 2006-03-04, 5:48 pm |
| BigAl.NZ@gmail.com wrote:
> Hi Guys,
>
> We recently got a Garmin GPS18 which we are using with GPS Gate to get
> the output to Virtual Serial Port.
>
> This GPS claims to be 5Hz update, yet when I connected to the virtual
> com port via Hyper Terminal the updates seem to only be coming about 2
> every second.
>
> Anyone know whats going on here?
>
> -Al
>
What do you mena by "5MHZ update"?
Are you talking about PVT transfer? If so Garmin's protocol
documentation says once per second.
--
Bruce E. Stemplewski
GarXface OCX and C++ Class Library for the Garmin GPS
www.stempsoft.com
| |
| Happy Trails 2006-03-04, 5:48 pm |
| On Sat, 04 Mar 2006 12:48:32 GMT, "Bruce E. Stemplewski"
<Bruce. Stemplewski@removeno
spamstempsoft.com> wrote:
>What do you mena by "5MHZ update"?
That's a bit quick, innit?
Happy Trails To You
| |
| Jack Erbes 2006-03-04, 5:48 pm |
| BigAl.NZ@gmail.com wrote:
> Hi Guys,
>
> We recently got a Garmin GPS18 which we are using with GPS Gate to get
> the output to Virtual Serial Port.
>
> This GPS claims to be 5Hz update, yet when I connected to the virtual
> com port via Hyper Terminal the updates seem to only be coming about 2
> every second.
>
> Anyone know whats going on here?
What baud rate are you using? Or is that configurable? If it is a 18
USB it might not be.
Jack
--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)
| |
|
|
<BigAl.NZ@gmail.com> wrote in message
news:1141475868.176624.51490@e56g2000cwe.googlegroups.com...
> Hi Guys,
>
> We recently got a Garmin GPS18 which we are using with GPS Gate to get
> the output to Virtual Serial Port.
>
> This GPS claims to be 5Hz update, yet when I connected to the virtual
> com port via Hyper Terminal the updates seem to only be coming about 2
> every second.
>
> Anyone know whats going on here?
>
> -Al
>
Did you get the 5Hz model? If so it looks like you need to configure it to
send the 5Hz pulses:
http://www.garmin.com/products/manu...ct=010-00321-05
| |
| BigAl.NZ@gmail.com 2006-03-04, 11:48 pm |
| They sent us the USB which looks like its 1Hz. Bugger will have to send
it back!
It took 10 weeks just to get the one we got - now its gonna be another
10 weeks....
-Al
| |
| BigAl.NZ@gmail.com 2006-03-04, 11:48 pm |
| I assume I read right - that the GPS18 USB doesnt have a 5Hz update
rate?
| |
| Jack Erbes 2006-03-05, 11:48 pm |
| BigAl.NZ@gmail.com wrote:
> I assume I read right - that the GPS18 USB doesnt have a 5Hz update
> rate?
Nope, that is a specific model, the GPS 18 5Hz, and it does not come in
a USB model. Full info here:
http://www.garmin.com/products/gps185hz/
I think the GPS 18 5Hz only comes with a cable with stripped and tinned
ends on the conductors. You'll have to make up your own connector and
supply 5V power. Full details in the manual at the link above.
You kind of have to be careful reading the specs and stuff there because
there is info on all of the different GPS 18 models there (GPS 18 PC,
LVC, OEM, USB and 5Hz).
Jack
--
Jack Erbes in Ellsworth, Maine, USA (jackerbes at adelphia dot net)
(also receiving email at jacker at midmaine dot com)
| |
| BigAl.NZ@gmail.com 2006-03-06, 2:48 am |
| I am assuming that you can make up a power connection via USB which is
5 VDC and should have no problem with 65 mA?
Then the data would go via RS232 and be powered from USB?
-Al
| |
| BigAl.NZ@gmail.com 2006-03-06, 2:48 am |
| Also I am curious - it talks about the pulse signal?
Is it really getting position fixes every 200ms or is it some kinda of
interpolation of your position based on the previous 4 fixes?
What do they mean when they say "Rising Edge"?
Cheers
-Al
| |
| Jack Erbes 2006-03-06, 5:48 pm |
| BigAl.NZ@gmail.com wrote:
> I am assuming that you can make up a power connection via USB which is
> 5 VDC and should have no problem with 65 mA?
>
> Then the data would go via RS232 and be powered from USB?
>
That should work. If you get a serial to USB adapter and can do a
little hardware modification it should be fairly easy. Here is an
example of one I happen to own:
http://catalog.belkin.com/IWCatProd...oduct_Id=109641
That uses the 5V on the USB bus to power the electronics (using a
Prolific PL-2303 serial to USB bridge) in the housing.
That does not pass the 5V from the USB bus on into the DB9P serial port
connector because that is not part of the RS-232 specification. But you
could probably open the housing and solder a couple of jumpers in to let
you use one or two of the DB9P pins not being used in the RS-232 scheme
to be used for the +5V and ground connections for the GPS 18. Then you
could put a DB9S connector on the cable of your GPS 18 and connect to
the serial to USB adapter for both power and data.
Having the 5V source on the pins in the DB9P connector is potentially
dangerous because that is not normally part of the RS-232 specification.
If you modified the serial to USB adapter to power the GPS 18 and then
plugged another serial device (other than your GPS 18) into it, the
presence of the 5V could cause damage to something and/or you could be
putting the 5V source on the USB bus at some risk.
So if I was going to modify an adapter like that I would mark and or
even "safety" the USB adapter so it could not accidently be used for
something else.
The serial connection from the GPS 18 only needs three conductors (TXD,
RXD, and Ground), or I guess four in your case if you are also using the
Measurement Pulse Output conductor. The same Ground can be used for
both power and RS-232 so there are plenty of unused pins in the DB9P
shell for you to use one of them for the power connection.
The USB bus provides for up to a 500mAH draw so there is plenty of power
there for the adapter and the GPS receiver.
If you're looking for serial to USB adapters to experiment with that are
on the cheap side, do a search on eBay for "serial to USB" and you'll
find a lot of them there. I'd look for one that comes with drivers and
it would be good if it was said to be using one of the more mainstream
IC's like the PL-2303.
I have a couple of generic serial to USB adapters that work as well as
the Belkin but I've also heard of people having trouble getting some of
them to work. I think sometimes that may be an issue with the knowledge
levels of the people involved and some of the foibles that arise from
various flavors of the Windows O/S, GPS receivers, serial mice, virtual
ports, etc. But a persistent "mad scientist" type should be able to get
it to work. :> )
Jack
--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)
| |
| Jack Erbes 2006-03-06, 5:48 pm |
| BigAl.NZ@gmail.com wrote:
> Also I am curious - it talks about the pulse signal?
>
> Is it really getting position fixes every 200ms or is it some kinda of
> interpolation of your position based on the previous 4 fixes?
>
> What do they mean when they say "Rising Edge"?
>
I'll defer to one of the true experts here for an explanation on that,
I'm more like a machinist with a smattering of extra knowledge.
I'd sort of like to know what you'd have to do five fixes a second
logged also.
Jack
--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)
| |
|
| Try out the USB-RS232 adapter before putting in the work modifying it.
The usual Windows problem is confusion between the GPS receiver and a
serial mouse. Windows gets confused and makes the cursor jump all over
the place. This problem is fairly easy to resolve - you have to disable
serial mice on that port or across the system. A web search should give
you the info you need.
I ran into one converter where the converter itself tried to recognize
a mouse. Unfortunately, if there was a gps present at startup, the
converter declared itself to be a different USB device type. There was
no way to disable it.
You want to put the 5V on a normally unused pin. I forgot which one I
used - pin 8? I think navtechgps.com sells a converter which has
already been modified.
- John Morris
PS Your testing should include hooking everything up, then turning on
power. That really brings out the "mouse" problem.
|
|
|
|