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Usb GPS module — Parallax Forums

Usb GPS module

Erik FriesenErik Friesen Posts: 1,071
edited 2007-07-20 11:31 in Propeller 1
Can anyone give me a quick overview of what it would take to interface one of the many usb gps modules to the prop?· Is there a 4800 baud serial data stream coming off the module that I could read directly or would it take a interpreter chip?

Comments

  • LeonLeon Posts: 7,620
    edited 2007-07-17 20:07
    Why a USB module? One of the RS-232 modules like those from u-blox would be easier to use.

    Leon


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  • RinksCustomsRinksCustoms Posts: 531
    edited 2007-07-19 14:17
    I have a module i got with microsoft streets and trips, but the usb chip got crushed in my door. I'm under the impression that any usb module like this has a baud rate of about 115K (USB 1.1?) but i got a feeling i'm wrong. I agree with Leon in that implementing a USB device with the prop will prove to be agrivating since you'll have to write a custom driver for communications.

    If your still inclined to go the usb route, i have the book USB complete, it's a few yrs old but good on info for 1.1 & 2.0 protocalls, and interfacing. If your so inclined to write a driver i know it'd be usefull in some projects, I don't recall anybody attempting a propeller based USB driver.

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    http://folding.stanford.edu/·- Donating some CPU/GPU downtime just might lead to a cure for cancer! The average PC while browsing the internet typically uses less than 30% of it's potential, why not donate a portion of the rest for cancer resaerch?
  • SteelSteel Posts: 313
    edited 2007-07-19 17:03
    I believe the USB Chip in the MS product is a custom ASIC, and not just a generic USB Chip (They would have to program the chip with there own vendor and product information in the configuration descriptors).·

    ...If you are set on using a USB GPS module, you would need a USB Host controller to talk to the Prop Chip, such as the FTDI Viniculum controller.· You will have to develop a host interface to talk with the USB GPS Device to make sure that enumeration a data transfers occur correctly.
    The USB GPS Dongle that you have right now is a GPS unit that spits out data in UART.·Then there is a custom ASIC that takes that UART and puts it in a USB Device interface.

    ...It may be silly to convert something from UART to USB just to tranfer it back to UART again...it would be cheaper, and a much easier interface to just connect a UART GPS Module directly to the Prop Chip.
    ·
  • LeonLeon Posts: 7,620
    edited 2007-07-19 17:04
    It would be feasible, someone has done it for an AVR. The controller can't do anything else, of course. Running the code on one cog would leave the other cogs free for other software.

    Leon


    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Amateur radio callsign: G1HSM
    Suzuki SV1000S motorcycle
  • RinksCustomsRinksCustoms Posts: 531
    edited 2007-07-19 18:42
    Uh, yeah, sorry i left that out. The ASIC was part of the cable going to the GPS reciever, so i might actually be able to use this GPS module then?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    E3 = Thought

    http://folding.stanford.edu/·- Donating some CPU/GPU downtime just might lead to a cure for cancer! The average PC while browsing the internet typically uses less than 30% of it's potential, why not donate a portion of the rest for cancer resaerch?
  • SteelSteel Posts: 313
    edited 2007-07-19 21:35
    you should be able to. look for any identifying marks on it, to make sure...but it seems pretty common practice for GPS Modules to just spit out UART.
  • Erik FriesenErik Friesen Posts: 1,071
    edited 2007-07-20 11:31
    Thanks for the info.· I have used the ttl modules and it is easy but there are no low priced ttl modules that I can find that come plastic covered and ready to go.
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