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Parallax GPS

amalamal Posts: 11
edited 2009-05-16 19:16 in BASIC Stamp
hii all
i am not sure if this is the right place to post my issue ..but anyway [noparse]:)[/noparse]
am working with a parallax GPS .. it got to modes .. and am working with the raw mode in which it dosnt need to be programmed
it just sends the NMEA strings.
i've connected it to my labtop serial port .. with the specifications of 4800bps, 8 data bits, no parity, 1 stop bit, non-inverted.
.. but i got just a rubbish data..!!!!!!!!!!!!! confused.gif

plzzzzzz help ... am i missing something ????????????????

Comments

  • SRLMSRLM Posts: 5,045
    edited 2009-05-14 07:09
    The GPS is a TTL level device. The Serial port is RS-232 (if memory serves right). You cannot hook them up directly to one another and expect to get good data, and you may have damaged the GPS and/or the serial port. You'll need some sort of converter in there.
  • amalamal Posts: 11
    edited 2009-05-14 12:14
    for sure i've did that ... i mentioned that am recieving data from it ... but it is rubbish data ....
  • sylvie369sylvie369 Posts: 1,622
    edited 2009-05-14 13:48
    Does it have a fix on the satelites? There's a red light on the side - when you've got a fix, it stops blinking and shows steady red. Until then you'll get largely garbage.
  • amalamal Posts: 11
    edited 2009-05-14 13:56
    yes.. it stops blinking .. i guess this is not my problem ... :S
  • SRLMSRLM Posts: 5,045
    edited 2009-05-14 14:34
    You could hook up two wires and jiggle them and get data. It would be rubbish data though.
  • sylvie369sylvie369 Posts: 1,622
    edited 2009-05-14 16:00
    How do you have it connected?

    If the light blinks and then goes solid red, you must have the right +5V/Gnd connections.
    If you're using·raw mode, you must have the /RAW pin connected to ground.

    Let's assume that much is correct.

    I assume you're reading the SIO pin for your data into a Basic Stamp, using the appropriate baud rate code on the Stamp.
    Which Stamp are you using?
    What does your SERIN statement look like?
    Are you using the correct code for non-inverted data? For a BS2 the Baud should be 188 (8N1, True).

    Then I assume you're sending the data to a Debug terminal using Debug statements, right? How are you doing that?
  • amalamal Posts: 11
    edited 2009-05-14 18:44
    hii sylvie

    i've didnt use it with any microcontroller yet .. although am going to use PIC 16F778A ..
    all what am doing is ... i 've connected the GPS to the computer using MAX232..the raw pin is connected to the ground..
    and since am using the raw mode .. am expecting to receive data only .. am not sending any type of commands ...i've got the specifications of the serial communication from the data sheet ( 4800bps, 8 data bits, no parity, 1 stop bit, non-inverted )... just to be sure .. the connections to a PC is normally inverted,,but am using the MAX232..so there will be no problems with that issue ,, right ???
  • sylvie369sylvie369 Posts: 1,622
    edited 2009-05-14 21:35
    Do the data received seem correlated with the actions of the GPS?

    That is, do they start coming in when the power is applied to the GPS, or are there data appearing on your screen even the GPS is unpowered?

    Do the data seem to change when the GPS gets a satelite lock?

    What I'm getting at, of course, is that if the answers are "no" then you've probably got a problem in your wiring. If the answers are "yes", then it could be wiring or settings.
  • ts-minits-mini Posts: 3
    edited 2009-05-14 23:47
    I need serious help with my GPS Module. I have the expensive GPS Reciever Module that is compatible with all the models of the BS2, or atleast it said it is. Regardless, I needed to upgrade to a BS2px and now the GPS in my program doesn't recognize the data or even the GPS module and neither does the GPS test program downloaded from the website. Upon retesting the module, it still works fine with the test program on a BS2, yet still no success on the BS2px. Any clue as to why and how i can fix this?

    Also, it has a solid red light when connected, so I know i acquire the satellites as the BS2 module works fine.
  • hover1hover1 Posts: 1,929
    edited 2009-05-14 23:56
    sylvie369 said...

    Do the data received seem correlated with the actions of the GPS?

    That is, do they start coming in when the power is applied to the GPS, or are there data appearing on your screen even the GPS is unpowered?

    Do the data seem to change when the GPS gets a satelite lock?

    What I'm getting at, of course, is that if the answers are "no" then you've probably got a problem in your wiring. If the answers are "yes", then it could be wiring or settings.

    Probably belongs in the Sensor Forum.

    But in the mean time...check out this post:


    http://forums.parallax.com/showthread.php?p=640507

    Are you using the same parts and connections that Chris is calling for? That would help to know that.

    Jim



    Post Edited (hover1) : 5/15/2009 12:14:20 AM GMT
  • hover1hover1 Posts: 1,929
    edited 2009-05-15 00:11
    ts-mini said...
    I need serious help with my GPS Module. I have the expensive GPS Reciever Module that is compatible with all the models of the BS2, or atleast it said it is. Regardless, I needed to upgrade to a BS2px and now the GPS in my program doesn't recognize the data or even the GPS module and neither does the GPS test program downloaded from the website. Upon retesting the module, it still works fine with the test program on a BS2, yet still no success on the BS2px. Any clue as to why and how i can fix this?

    Also, it has a solid red light when connected, so I know i acquire the satellites as the BS2 module works fine.
    Could you post your code? The BS2px has different timing specs for RS-232. Page 419 of the Basic Synax and Reference Manual (Ver 2.2)· has the Baudmode changes for the different BS2 chips.

    Just a note. You should have started a new thread. Different topic. Even so, we will try to help.

    Jim··
  • ts-minits-mini Posts: 3
    edited 2009-05-15 00:27
    sorry, first time on a forum.

    But here is the code that I'm adapting to work for our car.
    Also attached is the GPS Test Program

    would the baudmode cause that big of an error? what exactly does it do?
    zip
    zip
    Code.zip
    8K
  • hover1hover1 Posts: 1,929
    edited 2009-05-15 01:04
    ts-mini said...
    sorry, first time on a forum.

    But here is the code that I'm adapting to work for our car.
    Also attached is the GPS Test Program

    would the baudmode cause that big of an error? what exactly does it do?
    Try changing:

    '
    [noparse][[/noparse] Constants ]
    T4800·········· CON···· 188

    to

    '
    [noparse][[/noparse] Constants ]
    T4800·········· CON···· 813

    Baudmode specifies serial timing and configuation, (Baudrate, Parity-Non Parity, True-Inverted)

    It's a number that Parallax uses on the BS2 to specify serial parameters. It threw me for a loop when I started with the Basic Stamps.

    The Basic2 runs at 20Mhz where the BS2px runs at 32Mhz, so timing has to be compensated for because of the speed differences. That's where the baudmode comes in. Parallax has already calculated it for you!

    I haven't looked through the rest of the code yet, but try this and see what happens.

    Jim
  • ts-minits-mini Posts: 3
    edited 2009-05-15 03:51
    B.e.a.utiful.


    thank you. and that makes perfect sense now.
  • amalamal Posts: 11
    edited 2009-05-15 12:35
    hi sylvie

    my answer is yes .. but i think it is neither a wiring nor a setting problem .. because the GPS got 4 pins and am quite sure about their wiring,,and about the setting issue
    am using the RAW mode which demand the minimal specifications .. that is why am so confused about the output.... any suggestions !!!!!!!!!!!!!!????
  • amalamal Posts: 11
    edited 2009-05-16 19:16
    hii all .. my problem is solved.. i dont know what was the problem !!!! but any way ...all what matters now .. my GPS is working [noparse]:)[/noparse]
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