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Thread: Garmin Serial USB=Fast, USB BU-303=Slow?

  1. #1
    Join Date
    Apr 2004

    Garmin Serial=Fast, USB BU-303=Slow?

    I have a BU-303 and when I use it in conjunction with Mappoint 2004, perfomance is really horrible. Map refreshes are way too long, my position cursor disappears for a good 5 seconds sometimes, and Mappoint itself seems slow to use (ie, searching for POIs). Running AGPS with Mappoint results in waaaay lagged turn directions and very choppy voices. It's plain unusable.

    But I plug in my Garmin Rino 110 with a serial cable, and Mappoint runs as smooth as butter.

    I suspect that maybe the USB to Serial driver is bogging down the system when the BU-303 is in use. My system is a AMD K6-2 400mhz laptop with 128mb of ram running Win2k.

    Any ideas besides chuckin the antique laptop and spending money on something faster?

    edit: My title is mistyped. The Garmin is plugged in with a serial cable into a 9pin serial port on the laptop, NOT USB. The BU-303 is plugged into a USB port.

    Edit: The port settings for the bu-303 are at 4800,8,N,1. I even tried updating the Prolific drivers to (was at 1.4 before) with no improvement. I only have one USB port on my laptop so I can't try another port. I can't think of anything else to try


  2. #2
    Constant Bitrate faichiu's Avatar
    Join Date
    Sep 2004
    have you put the bu-303 on the roof of your car? bu-303 receive better if u put it outside of the car.

    98 Honda civic
    In-Dash LCD Monitor K-301
    cappuccino EZ3
    256MB PC133
    40GB HD
    Holux GR 213 Sirf Star III GPS
    CNX-P1900 power supply
    Sound Blaster Live USB

  3. #3
    Join Date
    Apr 2004
    Yes the BU-303 is on the roof of my car. And reception is good. But satellite reception doesn't explain why mappoint and agps bogs down only with the BU-303 and not the garmin.

    Something else I noticed. When connecting to the Garmin using Hyperterminal, I can see the NMEA Data stream. But when doing the same with the BU-303, there is a crapload more data. The BU-303 apparently does NMEA-0183 V2.2, I'm not sure what version the Garmin outputs. Could the expanded data stream be the culprit?

    When I check the Task Manager, my CPU usage when running HyperTerminal is about 15% with the BU-303. And it's only 5% with the Garmin... Hmm..


  4. #4
    Join Date
    Apr 2004
    bump! Still haven't solved the problem yet.
    Mappoint just chokes whenever it's connected to the BU-303. If the GPS is simply plugged into the USB port, but Mappoint doesn't connect to it, it runs smoothly and fast. Only after connecting to the GPS does it slow way down.

    I'm still leaning toward the idea that it's the relatively slow CPU bogging down with the USB-to-serial conversion. But someone else out there has to have tried using a BU-303 on a ~400mhz cpu...



  5. #5
    What can I say? I like serial. Curiosity's Avatar
    Join Date
    Mar 2004
    Florence Yall, BFKY
    How many NMEA strings does the Garmin spit out vs. the BU-303. Mine has quite a few more which means it's just doing more waiting on the BU-303 but the important info is really just coming at the same intervals. That's kind of a guess really.

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