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Thread: Help creating an LED matrix controlled by a microcontroller.

  1. #1
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    Lightbulb Help creating an LED matrix controlled by a microcontroller.

    Hi all, I've got a bit of a project on the go at the moment, and need some help!!

    My mother has got a 1971 type II VW camper, and whilst at a show we spotted some LED cluster rear lights which showed a 'VW' logo when the sidelights were on, and then a big block of them lit up red for brake lights, etc. she really wants a set making, but my idea is to give the design a bit of a twist

    my idea is to make a big matrix of 5mm LED's controlled by a PIC microcontroller, which (when off the road) displays a moving, rotating VW logo on the LED's, similar to the screensaver on most DVD players (like a DVD logo bouncing off the edges of the screen)

    Ive been looking around on the net for a bit and can only find dot matrix controllers which control a matrix of 5x8 LED's... the lights im going to be making are going to need a controller for say.... 20cm x 10cm, which is approx (40x20) 800 LED's... gulp. and thats a LOT of soldering for me as well lol


    Do any of you know of any controllers that can do this?

    the nearest ive found is on here... http://www.instructables.com/id/OSRA...ay-Module-Ini/

    they cant be controlled by a computer, and will need to have 4 inputs for brakelight, sidelight, indicator, and perhaps fog light too.

    all the controllers ive stumbled across seem to need to be connected to USB for them to work, which is unsuitable. it needs to be standalone, and runnable off 12v. I dont really know what im searching for at the moment though so perhaps im wrong


    If i cant get a microcontroller solution, it looks like its gonna be good old diodes and settle for a static VW logo

    using an LCD screen is out of the question because sunlight tends to blind them out, and it would look really gay anyway!


    I've got a budget of £120, ($200 ish) and they need to be built in time for VANFEST 2009 which is 11th to 13th of september.


    i was even hoping to get RGB LED's and have a craaazy setup... but the prices of the LED's will be about 60 billion quid.


    Cheers,
    Tom

  2. #2
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    Sounds like an interesting project. To drive that many LEDs it's best to use a multiplexing technique to reduce the number of output pins required. Using traditional multiplexing you'd need 58 output pins to control 800 LEDs, which is far more realistic than 800 pins. There's another multiplexing technique though, called charlieplexing. With charlieplexing you'd only need 29 pins, but it does have some drawbacks.

    As for the hardware, I can recommend using TI TLC5940 for controlling the LEDs and an Arduino microcontroller. It's very beginner-friendly and there is a library for the TLC5940 to make programming even easier. The library has support for multiplexing, though it's still a bit experimental. Using the TLC5940s will make the hardware design much easier. You'll practically only need 2 or 4 TLC5940s, an arduino and a lot of LEDs.

  3. #3
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    I can second the Arduino or AVR, but I'd suggest using one of the serial-input LED array devices. They significantly reduce the amount of wiring you need, which will be your major time expense on a one-off (or two-off :-) ) device like this.

  4. #4
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    Thanks for the pointers everyone, i'm gonna have a good search into those, and hopefully i can get something together
    i noticed a lot of books in the library today about the programming side of it so they should also help

    Tom

  5. #5
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    Have a look at SparkFun- they sell the kind of things you're going to need, in small quantities. Nathan's a top guy too- they'll help you out any way they can.

    http://www.sparkfun.com/

  6. #6
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    sparkfun is a great shop i have a funnel I/O and a arduino pro for my lamp i made u shake it to change the colour arduinos are very easy to use spark fun also sell RGB 8x8 led matrix's SPI controlled
    The glint in your eyes .....
    the warmth and the light ....
    is everything you love ...
    burning right before you ...

  7. #7
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    Quote Originally Posted by ionlaser555 View Post
    sparkfun is a great shop i have a funnel I/O and a arduino pro for my lamp i made u shake it to change the colour arduinos are very easy to use spark fun also sell RGB 8x8 led matrix's SPI controlled
    I have a couple of those arrays, they're nice but not very bright.

  8. #8
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    replace it by a "EDIT: removed due to a project to be released "

    sorry for that, but this idea is something I must do, and post here, as it is more than UBER

    btw do you know of something that fluoresces with IR light? I might need a non-nasty dye for this purpose

    to sta within subject:

    perhaps driving your cube's common pin with a pulsed higher current supply would drive more visible light out of the leds

  9. #9
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    You need a dye that absorbs or emits IR? Most of my dyes have some NIR emission, but typically you should look at the lanthanides for IR activity.

  10. #10
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    yeah ive looked at the sparkfun modules working on YouTube etc, and they seem too expensive, and the LED's will have to be ultrabright anyway as they'll be replacing the existing lights.

    I wish i had more free time on my hands!


    EDIT: shrad, do you mean making the same thing as i am? if you could get the PIC thingies configured/layed out etc then i'd pay you! lol

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