Numpty's Progress

Month: December 2010

  • Interfacing the Pharos GPS-500 to Mac OS X

    Update 2015: This is very old. I don’t know the status of a decent OS X 10.10 driver for the Prolific PL-2303 in this GPS.

    I’m stopping short of calling this “Using the Pharos GPS-500 to Mac OS X” because all I’ve been able to do is read raw NMEA sentences from the device. But that might be of use to you.

    The Source is clearing out copies of Microsoft Street & Trips with GPS 2008 for $20. The GPS is a very simple USB Pharos GPS-500, which uses the SiRF III chipset. Between the USB cable and the GPS is a small black box which looks suspiciously like a serial to USB converter. I have no use for the software, but the GPS is a bargain, considering a similar bare unit costs $60.

    Plugging it into a Mac does nothing beyond being recognized as a “USB-Serial Controller D” from Prolific Technology, Inc. The ancient driver on Pharos’ website identifies the serial chipset as the Prolific PL2303. The only driver I could get to work with Snow Leopard was the failberg/osx-pl2303, a fork of an earlier project from Sourceforge. You’ll know if it’s working when you get a device called /dev/tty.PL2303-something appear.

    Reading the data’s pretty simple if you have GNU Screen installed. I entered the following command:

    screen /dev/tty.PL2303-12345678^XX^D?^XX 4800

    and very quickly started to get NMEA data scrolling in the terminal:

    $GPRMC,003322.000,A,4343.8349,N,07915.8845,W,0.38,112.13,211210,,,A*7B
$GPGGA,003323.000,4343.8351,N,07915.8838,W,1,05,2.8,174.3,M,-35.1,M,,0000*65
$GPGSA,A,3,09,18,14,21,22,,,,,,,,6.9,2.8,6.3*34
$GPRMC,003323.000,A,4343.8351,N,07915.8838,W,0.89,122.04,211210,,,A*76
$GPGGA,003324.000,4343.8351,N,07915.8843,W,1,06,1.5,176.0,M,-35.1,M,,0000*62
$GPGSA,A,3,27,09,18,14,21,22,,,,,,,3.4,1.5,3.1*30
$GPGSV,3,1,12,18,78,082,28,22,61,307,27,09,56,076,30,27,40,053,19*7F
$GPGSV,3,2,12,14,38,254,18,21,32,180,21,15,27,062,16,26,12,059,*7E
$GPGSV,3,3,12,19,10,302,,12,07,119,,06,04,261,,03,02,272,*7E

    To stop screen, type Control-A K. Do not just unplug the GPS, as you risk your machine crashing.

    These NMEA sentences can easily be converted to GPX.

  • Magellan Triton 400 micro-review

    My office’s Garmin was stuck in a branch office last week, and we needed a GPS for the next morning, so we got a cheapo Magellan Triton 400 for $90 at Future Shop. I think that’s a clearance price, and none of the big-box retailers still carry it.

    The Triton 400’s a Windows CE unit with a surprisingly good display for the price. I only had a little time to set it up and test it briefly outside the office, so all I can do is give you is first impressions.

    Pros:

    • Cheap!
    • SIRFstarIII chipset for reasonably fast/accurate acquisition
    • SDHC card (worked with my 4GB card)
    • Bright display
    • Works with GPSBabel (as Magellan’s VantagePoint obviously installs a copy)
    • Doesn’t route

    Cons:

    • Wouldn’t acquire any position until I updated the firmware (at which time I discovered that it basically updates a full Windows CE image from an archive)
    • Weird proprietary USB cable
    • Tiny buttons that aren’t very positive
    • Eats batteries
    • Overly simplistic menu structure makes it hard to set up
    • VantagePoint is buggy, and will repeatably crash under certainly (admittedly rare) menu items
    • Only works under Windows; the USB protocol is proprietary
    • Hard limit of 5000 points per track, and track logging stops when this limit is reached
    • SD card is only usable for maps and geotagged photos, not track storage.

    I should be able to play with it in more detail in the new year. It was cheap, but not all cheap things are good.

    More on the Magellan – OpenStreetMap Wiki page.