Sunday, January 31, 2010

GPS Speedometer project

Here is a project I worked on a couple of months ago that I thought I'd like to post before I "reclaim" the parts into something else.


Inside the trendy "lunchbox" is a small GPS sensor and a PICAXE that work together to display the current speed in Kilometres-per-hour (KPH) on the display - forming a universal speedometer. In an attempt to make this project as simple as possible, the PICAXE uses PWM to output 0-200mV to a 0-200mV DC Voltmeter. This removes the need for a (more expensive) dedicated LCD as the circuit can be connected to any multimeter with a 200mV range setting.


The program reads in the KPH from the GPS unit (one of these) using the serial pin, multiplies that number by 4 and sets its PWM output to the result.

The PICAXE code is available here on GitHub.

The PWM output ranges from zero the supply voltage to the chip - in this case 5V. This is then limited to 0-3V by a Zener diode and further reduced to 0-200mV using a potentiometer wired as a voltage divider.

The result is an accurate speedometer that can be used in a car, boat, bicycle, motorcycle without any sort of special configuration and that costs virtually nothing. Performance-wise, it updates once every second and the speed is steady and accurate to within +/- KPH at highway speeds.

32 comments:

  1. plz, can you write me the components used in your project of GPS speedometer.
    plz reply me soon

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  2. Hi Neel. I will draw up a diagram with the components this weekend and post a link to the diagram in the comments. Cheers, Robert

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    2. Hi zubair,

      Unfortunately I don't have any diagrams other than this one: http://github.com/thisismyrobot/GPS-Speedo/raw/master/circuit.png - a drawing of the output from the Picaxe. I have since recycled the components of this project so I cannot produce another one, although the .bas file identifies the input/output pins fairly clearly.

      I haven't got any experience with other pic programming, I would suggest re-writing the .bas in the language for your pic would be the fastest, as the .bas code is very simple.

      Cheers,
      Robert

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    3. THANK YOU ROBERT,
      If you know or have any example code for pic please could you share_? here i did not found picaxe so i want to use pic or atmel. any idea or weblink like your project. i would be appreciated.
      thanks again
      regard
      zubair

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  3. thanks buddy, i will take your help when required.

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  4. i haven't got your diagram of project, so plz reply me when & where are you placing it?

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  5. Sorry Neel, got caught up in other things at the start of the weekend. I have drawn out the diagram of the circuit from the output of the Picaxe-08M to the input to the multimeter (http://github.com/thisismyrobot/GPS-Speedo/raw/master/circuit.png).

    The Picaxe code is linked on the blogpost above and will give you all the info you need to talk to the GPS module etc.

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  6. Hey Robert i was talking about whole circuit diagram from gps receiver to seven segment display, and what components were used in your whole project so that i could able to find components in India!

    ok, so plz make soon as date is coming near for submission of project.

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  7. Hi Neel. There is nothing else really in the project.

    As I said in the article, the right-hand-side of the circuit diagram goes directly into a 0-200mV Voltmeter - one of these:

    http://littlebirdelectronics.com/products/3-5-digit-jumbo-led-panel-meter

    Using the voltmeter was a cheap and simple solution instead of a proper 7 segment display.

    The left-hand-side is connected to Picaxe 08M (on Pin 5), running the code that is linked in the article. The pin-out of this chip is available here:

    http://www.rev-ed.co.uk/docs/axe230.pdf

    and the code is linked to above.

    The GPS module is also linked to above, and its serial output is connected to the only serial input on the Picaxe, Pin 2.

    The photo above is a bit more complex than the finished circuit, but gives you the general idea. The project was only ever made on prototype board and doesn't have a definitive list of components - that's the fun of designing and building it yourself :)

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  8. sorry for disturbing you again & again, but i didn't understand as it is explained separetly, so plz combine each & everything and prepare whole circuit diagram very soon as it has remained less time for submission of project.
    and sorry again for disturbing.

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  9. Sorry Neel, but his project requires a fairly comprehensive electronics and programming knowledge to build and configure - it is not a project that can just be built from a circuit diagram.

    If you require a complete project with detailed instructions, I would try this one: http://www.sparkfun.com/tutorials/123

    Cheers,
    Robert

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  10. so does this gps receiver & picaxe-08M requires programming to run & if it is, plz let me know.

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  11. Yes, the Picaxe-08m requires the program that is linked to in the article above. The GPS does not require programming.

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  12. so plz write me the program and software details in a link for this project you have used.

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  13. I don't mean to be rude, but I have said 3 times that the link is above in the article.

    The url is http://github.com/thisismyrobot/GPS-Speedo/blob/master/speedo%20gps.bas

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  14. ok dude very sorry for such rude behavior with you i agree that i am asking yo usuch questions but i am student of diploma engineering and doesn't know much about programming.
    so one last thing which software was used for loading program in Picaxe-08M and does it requires a IC loader?
    I know you must be tired of me but this is last thing i want.
    sorry friend again.

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  15. Hi Neel. Hopefully this will help you get over the line. The Picaxe is made by Revolution Education:

    http://www.rev-ed.co.uk/picaxe/

    The software and datasheets for programming are on the Revolution Education website.

    To program the Picaxe 08M I used the Picaxe 08M Starter Pack and a Programming Cable.

    Starter pack:
    http://www.sparkfun.com/products/8323

    Programming Cable:
    http://www.sparkfun.com/products/8312

    This allowed me to experiment with the Picaxe before putting it into the GPS Speedometer. Good luck!

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  16. Hi Robert I have tried to design according to diagram shown on front page which is on bread board. But it is not able to see correctly that paths you joined on bread board from voltage regulator upto the PICAXE pin.
    so plz at last try to draw up diagram showing paths correctly.
    Thanks.

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  17. Hi Robert, the project is good but te display you prepared for it plz show or guide me to prepare a simple 4 digit display.
    does this display used atmega IC in display.
    plz reply me soon.
    thanks.

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  18. Hi Neel,

    The LCD I used is a voltmeter. It is set to display 0-200mV. This is used to represent 0-200 km/h. Unfortunately I don't know how what ICs are inside.

    You can easily test the project using a standard Multimeter set to 0-200mV.

    Cheers,
    Robert

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  19. Hi Robert, after a long working on your project I ound a little bit difficulty in project.....
    what IC you have used as voltage regulator as shown in diagram from input voltage, bcoz i have used IC7805 voltage regulator & also what you have used as battery source power and where it is available.
    If you don't mind can you give your contact number with country code or you have facebook id then plz reply me....its urgent..

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  20. Hi Neel,

    I used a 7805 as well, and I used a standard 9V battery. The circuit is very low current so the 9V battery lasts a while.

    I get an email when you comment here so I am able to reply just as quickly.

    Cheers,
    Robert

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  21. so which kind of battery is used which provide less current requirement according to MN5010HS about 46mA maximum.
    i have used 9V PP3 battery..

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  22. Yeah, a 9V PP3 is what I used to.

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  23. Hi Robert, on Tuesday is my submission so will you plz tell me that what kind of programming is this and which software is used any kind of programming language.
    list me the resistor values you have used with zener diode and along between capacitor and potentiometer as seen in diagram.
    and also most important you noticed me to place serial input to pin no 2 of picaxe but as seen in diagram it is placed on pin no 3. so clarify it soon within few hours.

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  24. Hi Neel,

    The PICAXE chips are all programmed in PICAXE BASIC - the programming IDE is downloadable off the PICAXE website (http://www.rev-ed.co.uk/picaxe/). My code is linked to my article.

    Sorry for the confusion with the photo vs. the diagram - I made some changes after the photo was taken; the resistor in the photo between the potentiometer and the capacitor is not necessary and the Zener is not included as I added that later. The diode in the photo between Pin 3 and Pin 1 was a recommendation from the manual to help with serin - but you don't need that either.

    Also, Pin 2 was a typo in an earlier comment - I read the GPS data on PICAXE Pin 3, Serial In is used for programming and is Pin 2.

    Good luck with your submission!

    Cheers,
    Robert

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  25. the last final thing does GPS receiver light remains on continuously as battery is connected, bcoz when i connect battery with receiver it glows and goes off as soon as connected.
    bye and thanks for your best project

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  26. The light stays on until the GPS locks and sends the first coordinate, then it turns off. No probs, hope it all goes well :)

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  27. I love these projects.
    I have used this GPS with great success, the main advantage being the $29 price tag.
    I am using one just to provide a accurate time base for a weather station project.

    http://shop.4dsystems.com.au/gps-modules-accessories/246-9102.html

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  28. A decent GPS cruiser unit will come preloaded with an enormous number of maps, thus you can explore your route right the nation over with the maps supplied.
    http://gpscustomerservice.com/gramin-issues

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  29. It is also possible to track the movement of the tracker across various sessions simultaneously. Location data of the tracker can be stored in a central location if it is required. Family locator

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