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Thread: NEED GPS TUTORIAL

  1. #1

    Default NEED GPS TUTORIAL

    Hello all,

    For making my autonomous robot helicopter project, i need to learn about gps tracking with a microcontroller can anyone suggest how to use gps with a microcontroller and where to buy them and how to set up gps communication ???

    Regards ... Jaydeep

  2. #2
    Senior Member Cyborg
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    hello superchiku,

    Tracking with gps is easy to do thing. Most or almost every GPS module gives standard NMEA sentences (start with $ sign) tru serial. You just have to parse these sentence using standard UART of any mcu.

    For your hint :-
    use GGA sentence it gives latitude and and longitude and many other info abt the point in consideration.
    $GPGGA,hhmmss.ss,llll.ll,a,yyyyy.yy,a,x,xx,x.x,x.x ,M,x.x,M,x.x,xxxx*hh
    and RMC gives the time and date info (GMT).
    $GPRMC,hhmmss.ss,A,llll.ll,a,yyyyy.yy,a,x.x,x.x,dd mmyy,x.x,a*hh

    but one important point these data are ONLY valid when you get a fixvalid string equal to "1", in the $GGA sentence otherwise data is not correct and should be rejected.

    to working with GPS i found one have to be good in string manuplation.
    and look wheater your complier support atoi, atof like functions (if have to do calculation using data) or else u can make one of your own.

    one more thing it is not good to start directly with live NMEA sentence from module as it mostly hang up our code (personal exp. ) first one have to build algo/ code structure using constant NEMA sentence giving it to uart i.e. more like that of simulation. It enable us to build algo more strong to face the random data. This make working on GPS more easy as one could do as much trail before spending on real module.

    anyways, i think this is a sort of short tutorial and may help you
    Nikhil Chandra | Bangalore

    Imagination is more important than knowledge.

  3. #3

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    Thanks for the info but can u tell me where can i buy them and how to interface them with a microcontroller , yes i can use uart to send down strings to the gps but how does it exactly navigate and will the microcontroller realise how to affect the sensors or how to affect the motors and all to move the helicopter

  4. #4
    Super Moderator T-1000 docel's Avatar
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    ..Chiku!!
    That sure is an ambitious project , indeed 8O 8O
    Controlling a Heli is not easy, if noone has told you yet.
    Making and controllig is even more not easy!
    I hope you know what you are getting into.......
    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

  5. #5

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    i know it isnt easy, the electronics isnt easy and the cost is high but if one can do it then all can , also there is no hard in trying

  6. #6
    Senior Member Cyborg
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    i can use uart to send down strings
    you dont send anything to gps module(if not config.). it itself give u info. i.e. NMEA sentences continuously and it can be received through UART of mcu. then mcu take the info from these sentences. just take it as sensor with give u data i.e. Lat, Long, Alt,..etc through serial port.

    For real time navigation we have to calculate distance using equations like "haversine" equation, which is trigonometrical calculation. For that u will be needing very high processing mcu. as doc said it not a very easy as it sound (navigation). I use ARM cortex @72mhz for this.

    and about module availability there are many source in India itself.
    Nikhil Chandra | Bangalore

    Imagination is more important than knowledge.

  7. #7

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    ARM CORTEX where is it exactly found???

  8. #8
    Senior Member Cyborg
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    ARM CORTEX where is it exactly found
    actually that time i was just showing off !!!!
    :lol:
    anyways its an ARM processor superior to ARM7, and ARM9. And had i used stm32 its an ARM based microcontroller from ST.
    Nikhil Chandra | Bangalore

    Imagination is more important than knowledge.

  9. #9
    Senior Member T-1000 debu's Avatar
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    Quote Originally Posted by shashak
    ...its an ARM processor superior to ARM7, and ARM9...
    Really? :roll:
    The Cortex-M3 (aka STM32 family) IS ARM7. Its simply optimized for IO, so the onchip IOP is different, it uses a Seprate CM3Core (clickie), along with the ARMv7 core and the CM3Core (clickie), uses NVIC's (Nested VIC's) instead of the old fashioned VIC's of the earlier ARM family. The other main difference is that the seperate VDDCORE, VDDIO, VDDFLASH, VDDPLL,... etc. have all been integerated at 0-3.6v on the same net as VDD and VDDA.

    Sorry for going so thoroughly off-topic.

    Regards,

    Debu

  10. #10
    Senior Member Cyborg
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    oh debu come on as i told frankly i was just showing off!!

    anyways your own post substantiates the cortex M3 contend, in past 5 month i have used arm7(LPC2138) arm9(STR9) and cortex m3, and in all i found cortex m3 mix of arm7 convience and arm9 power, a personal opinion biased of hangover and may be very superficial.

    as word "superior" may be inappropriate i could have use "predecessor".
    Nikhil Chandra | Bangalore

    Imagination is more important than knowledge.

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