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LED timing with multiple variables??

Discussion in 'LEDs and Optoelectronics' started by Bernard_Concannon, Aug 28, 2014.

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  1. Bernard_Concannon


    Aug 28, 2014
    Hi all,

    I am trying to use LEDs to replicate the timing of Navigational Marks. I assume that it will involve a timer of some kind (555?). The sequence can be complicated though....

    There would be a lot of potential sequences, but one example might be:

    (Flash for 1 second - off for 1 second) repeat 6 times. Then flash for 2 seconds. Then off for 5,10 or 15 seconds. Then repeat the whole sequence.

    Any suggestions on how this might be achieved...?

  2. Arouse1973

    Arouse1973 Adam

    Dec 18, 2013
    I think you will struggle to do this with a 555. Your best bet is going to be a micro processor.
    Gryd3 likes this.
  3. ketanrd01


    Aug 11, 2014
    Instead of going for a complex ckt using timer IC 555, use a simple ckt consisting of an 8051. I could send you the code if you wish...
  4. Gryd3


    Jun 25, 2014
    @Bernard_Concannon , the microprocessor idea is ideal. You have a wide range of products and prices to choose from.
    They will allow for low component count installation and can control anywhere from a single LED to hundreds depending on your application.
    What's more, is if there is ever a need to change the pattern even in the slightest way, you would not need to re-engineer your circuit.
    You would merely need to upload a new program to the microprocessor and be done with it.
    KrisBlueNZ likes this.
  5. Bernard_Concannon


    Aug 28, 2014
    Hi all, thanks for all the feedback. A micro processor sounds we could potentially have dozens or hundreds of LEDs depending on the application.

    However, although I am fairly hands on and electronics experience is fairly limited. What is involved? What components would I typically need? How do you programme a microprocessor? What's the language/syntax? Could one processor control all of the LEDs if each had a different sequence?

    Thanks again for all the help!!!!
  6. Gryd3


    Jun 25, 2014
    First step would be buying a micro-processor. To learn, you would need the μprocessor itself, some resistors, LEDs and transistors. Optionally, you can get a potentiometer/trim-pot or two or some buttons that you can use as an 'input' for your processor.
    A micro-processor is programmed from you computer and can be done fairly easily. Some require a 'programmer' which is commonly a USB device that you connect between your computer and circuit/processor. Some bypass this, like many Arduino... they simply have a usb socket and you plug them right into the computer.
    A common language is C, but there are derivative languages that follow the same general structure and change or add functions. This will vary depending on which processor you go with.
    How many LEDs do you plan to control with your final project, and will the lighting sequences be pre-programmed, or will they be generated on the fly?
    You have a couple options:
    -Buy a processor with lots of inputs and outputs, and optionally buy components like 'io expanders'.
    Two things will limit you here. Processor memory, and how often you will be updating the patterns. (Fading LEDs, or very fast flashes will not scale well... only if you want individual control of each LED. You can always control groups of LEDs at the same time, which will cut down on how many pins you need and the memory required)
    -Buy multiple processors.
    The main processor will act as a sort of concert conductor, and will tell each sub-processor which pattern to play. This has the benefit of finer control for larger amounts of LEDs you wish to connect, but making new patterns on-the-fly may be more difficult.

    If you can provide a little more info we can suggest more info ;)
    Will the (or some) LEDs be grouped together and act in concert, or will each LED have a unique pattern?
    Will each LED be capable of multiple patterns, or a single hard-coded pattern.
    How many unique patterns are desired, and can you describe one or two of the patterns you would like?
  7. Bernard_Concannon


    Aug 28, 2014
    @Gryd3. Thanks again...going to take a bit of time to process all that and have a think!

    I will post back again, but wanted to acknowledge your input in case it's a while before I reply!
  8. Colin Mitchell

    Colin Mitchell

    Aug 31, 2014
    Instead of going to a great big 8051 you can try an 8-pin PIC12F629 where I have produced all sorts of timing and flashing sequences for a LED and a number of LEDs.
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