Just in case someone else ends up with the Pharos USB GPS (the one that comes with Microsoft Streets & Trips with GPS). This device is a USB-only GPS receiver powered by SIRF III technology. It reads model no. GPS-500 and part no. X13-51914.

Instead of buying a separate Bluetooth dock, I thought I would try and make use of the USB host mode that comes with OS versions chinook and up. A specially modified adapter does the specific trick of automatically switching the USB mode.

The Pharos USB GPS-500 receiver has a built-in Prolific USB-serial interface. N800 however does not come with the necessary modules and drivers to perform USB-serial interfacing. Fanoush was kind enough to make available a module pack (tar.gz) (see also this post) containing suitable modules: usbserial.ko and pl2303.ko under drivers/usb/serial. These of course will have to be loaded with insmod from the root account. Upon successfully insmodding, a new /dev/ttyUSB0 serial device is created.

One last trick I had to figure out was a hidden file called /var/lib/gps/.gps_no_serial_ports which will prevent maemo-mapper and the built-in gpsd daemon from accessing /dev/ttyUSB0. Once you remove that file everything should work like a charm.

The following steps are involved:

Maemo-mapper will have to be configured to use the serial device /dev/ttyUSB0 under Settings/GPS/File Path. Make sure you write down the default /dev/pgps somewhere before replacing just in case it may prove critical some time in the future.

Cheers

Z

2/7/09 Edit: here is an implementation suggestion in conjunction with the Personal Menu app. A notable change from the example above is the use of gpsd as data source in maemo-mapper as opposed to pointing it to /dev/ttyUSB0. The scripts below will fire up gpsd with the right command-line options, This way several gps-enabled applications can run simultaneously.

Caution: some unix/linux skills are required, such as opening an xterm session, navigating the file system using cd and ls, copying and renaming files etc--

(1) I opened a Terminal session and created a new directory called /home/user/bin/usbser containing the following files; the .ko files are the new kernel modules described above:
The other 3 files are simple shell scripts as shown below:

start-gpsd restart-gpsdstop-gpsdThese scripts can be created on your PC using notepad then copied over a USB cable on the internal or external card. Then you could open a terminal session and copy the new files from either your external card (found at /media/mmc1) or internal (/media/mmc2). An alternative of course would be to create said shell scripts in vi or any other editor you may have available that can save plain text files (I for one use mc / mcedit).

With all files in place, I made the scritps executable: chmod +x *-gpsd.

(2) I installed Personal Menu. Then using the Edit Personal Menu option, I created entries for the scripts above and checked the "run as root" box; here are excerpts from my ~/.personal_menu.rc config file:

(3) Logged in as root (see below posting from Aquabits describing how to do this,) I went ahead and added the following line to the bottom of /etc/sudoers:

(4) One final step is to set maemo-mapper to use gpsd on localhost port 2947.

The "restart-gpsd" command above is sometimes useful when maemo-mapper is unable to locate the gps device; this most likely happens when the OS (stubbornly) recreates the .gps_no_serial_ports file.

Hope this helps

Cheers

Z.

I wondered if there was a way to get that GPS to work. Especially since it was $29.99 on woot about two weeks ago.

So, since it's working, how is the reception on it? Is the lock time fast? Does it really drain the power pretty fast?

It locks within seconds (less than 10 in my case). I take that back, it locks within 20-30 seconds if no prior gpsd instances are active.

I had the entire setup on battery for about about 3 hrs before it drained.

Very cool indeed...

Is your USB GPS two seperate peices not including the modified adapter? I have one from Microsoft Streets & Trips laying around here somewhere that has a postage stamp sized GPS reciever that plugs into a seperate USB-serial interface.

Now I'm wondering if this smaller serial interface with the modified adapter can be used for connecting other serial devices with the Tablet.

You're right, it is the two separate parts one, see attached, blurry pic. In my very limited experience with serial devices I have never seen a serial connector like this one in the past, so it may actually be Pharos-specific.

Z.

Just for the record, Zzzy instructions worked *great* for enabling a Holux GR-213 ("GPS mouse" serial receiver) plugged into a Nokia N800 using a Holux USB adapter cable (which contains a Prolific PL2303 serial-to-usb chip): maemo-mapper is working wonderfully.

If afterwards it stops working, just see it the /var/lib/gps/.gps_no_serial_ports is back there, and if so, just remove it and restart maemo-mapper. That happened to me, I think some program in Maemo recreates it from time to time.

Cheers,
--
Durval Menezes.

I had worked this out a couple of months ago, but did't have a chance to write up a tutorial. I used a BU-353 and I also get about 3 hours of continous mapping with my n800. I believe the SirFSTAR III chipset uses 70 mA.

Would be nice if someone could package this all into an installable .deb file.

Thanks much to zzzy (and Fanoush).

Few tips for newbies like me:
- The device zzzy mentiones comes with 2007 version of MS Streets&Trips. Older versions may have a slower GPS chip.
- The insmod command is only available when you are logged in as root. To do it, you can use the "rootsh" program which when installed, shows up as "x-terminal". Issue "sudo gainroot" in x-terminal and you are root.
- You can use a regular mini-usb adapter, but you will have to manually put N800 in host mode. To do so, you can use the "usbcontrol" program. Once it is in host
mode, you can exit the program.
- Make sure to delete the hidden file, even though you may not see it.
- When you plug-in the GPS, N800 will recognize "a usb device". You will get a message about unknown file system, just ignore it.
-The default Map program won't work with this. You will need Maemo Mapper.
- Do the settings change for ttyUSB0 in Maemo Mapper and then go to GPS->enable GPS. It will take a while for it to find the device and get a lock on it.
- Use the center button on the pad on N800 to center the map to your location.
- Additional maemo mapper information here.

By the way, I have N800 and the latest OS2008 version (4.2008.36-5). This GPS works on it with the steps described in the initial post by zzzy.