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[help] Multi Function Display - uC project..

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by m23404009, Oct 5, 2007.

  1. m23404009

    m23404009 New Member

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    guys.. need some help here.... i have an assignment.. details are below...

    I'm planning to make some kind of Multi Function Display that usually used in an expensive cars.. it'll shows:
    1. Time and date
    2. outside temperature
    3. rear distance (i'm thinking about parking aid using ultrasonic..)

    number 1 & 2 are done... the main problem is number 3..

    problem 1. since the sensor will be located outside the car, it must have some kind of weather-protection (rain, dust, etc)... Do you have any idea?

    problem 2. do you have any reference about making the parking aid sensor? because, i've tried to built just a distance meter and it doesnt work.. my method is to measure the time delay between transmitted and received signal..

    thanks..
    (Timothy)
     
  2. picbits

    picbits Well-Known Member

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    You can buy sealed ultrasonic transducers for outside applications.

    Might help if you let us know where you're located and people could perhaps suggest local suppliers.
     
  3. Torben

    Torben Well-Known Member

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    Hi Timothy!

    Saying "it doesn't work" doesn't really help us--we can't guess what you've tried and why it might have failed. Presumably you're using a microcontroller of some kind? Matched ultrasonic piezos or similar?

    There are many sonar rangefinders on the net and they've been discussed on these forums quite a bit. One of the more complete articles I've found is from the November 1998 Everyday Practical Electronics: http://tech-www.informatik.uni-hamb...-ultrasonic/epemag-nov98-pic-tape-measure.pdf

    There is another helpful article here: http://www.picbasic.org/articles/ultrasonic/ultrasonic_experiments.html

    But anyway: what have you tried? What do you mean by "it doesn't work"? That could mean anything. What are the maximum and minimum distances you would like to measure? Is this for a real installation (I am guessing so since you want the weatherproof transducer) or does it just have to work on the bench? Are you using two matched transducers or just one, and switching it quickly between transmit and receive?


    Torben
     
  4. dave

    Dave New Member

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  5. m23404009

    m23404009 New Member

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    @picbits
    i'm located in Indonesia.. I've tried searching for a weatherproof tranducer, but it's way to expensive.. I'm trying to build inexpensive gadgets.. Anyway, I'm thinking to put the tranducer inside a box and place it under the rear bumper..
    what do you think?
    in addition, my car is a sedan..

    @torben
    i've tried to build a distance meter using microprocessor. the algorithm is to measure the time delay between transmitted and received signal. "It doesn't work" because it can only measure for a short distance (less than 10cm). I need to measure up to 1m (with minimum distance --> +/- 10cm). Since it was an assignment, i can't buy sensor like ping (parallax) nor the range finder (devantech)..

    thanks for all your help, and i'm really sorry if my english is so bad..
     
  6. Torben

    Torben Well-Known Member

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    Hi! Your English is fine. The words are OK, but you need to post more of them to explain what you are doing. Post the schematic which does not work. You have said only that you are using a microcontroller to measure the distance, but not *how*. There are many ways to do what you describe, and even more ways to get it wrong.

    What transducers are you using?

    What amplifiers and/or comparators are you using on the input?

    Post your code.

    Post your schematic which isn't working for you so we can at least see what you've done. Without this we can only guess what might be wrong.

    You say it measures only short distances. It could be that the transducers are mismatched (you still haven't said whether you're using one or two--two is easier to start). It could be that your transmit power is too low. It could be that your input is not sensitive enough. It could be that your code is not waiting long enough between pings to allow longer distances.

    Please, post your work so far. Explain in more words what you have done and why it is not working. Do not worry that your English is not good--it is fine. Just post more of it! :)


    Torben
     
  7. m23404009

    m23404009 New Member

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    okay... i'm working on it... I'll attach my schematic and the code ASAP...
     

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