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Lots of LEDs — Parallax Forums

Lots of LEDs

kingspudkingspud Posts: 128
edited 2006-05-05 18:04 in General Discussion
Hello all,

I am doing a project with around 100 LED's!· I want to be able to control each one separately and be able to turn it on or off with a button.· I know I can use Decoder chips to control 7 LED's but I want to use the SX chip to control multiple decoder chips, which will control each of the 100 or more LED's!· Is this possible??

Any help would be appreciated!

Thanks
Joe

Comments

  • Jon WilliamsJon Williams Posts: 6,491
    edited 2006-05-03 21:54
    If you can control one decoder, you can control bunches -- many can be daisy-chained to save I/O pins.

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    Jon Williams
    Applications Engineer, Parallax
  • kingspudkingspud Posts: 128
    edited 2006-05-03 21:55
    Normally you have 4 inputes to get 7 different displays right? So if this is so I think the SX can be programmed to control the first four inputs and cascade down from there!
    How far do you think I could go with this before the SX is overloaded?
    Joe
  • kingspudkingspud Posts: 128
    edited 2006-05-03 21:56
    Also, does anyone have any sample code for just controlling a decoder and one seven segment led?
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2006-05-03 21:58
    I would use something like a 74HC595 where you get eight outputs with three I/O pins; connect another (daisy-chain), you get 16 outputs with the same three pins.· See the example for SHIFTOUT in the SX/B help file.

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    Jon Williams
    Applications Engineer, Parallax
  • T&E EngineerT&E Engineer Posts: 1,396
    edited 2006-05-03 22:37
    Look at the MAX7219 which is also sold by Paralax. It will control up to 64 LEDs or 8 7-segment displays.

    They can be daisy chained too but I have yet to get it to work right.

    Jon has a Nuts and Volts article about interfacing·it with a BS2.

    http://www.parallax.com/detail.asp?product_id=603-00001

    Thanks.
  • pjvpjv Posts: 1,903
    edited 2006-05-03 23:55
    Hi KingSpud;

    It's not clear from your post whether or not you need more than one LED on at one time. If you only need one (any one that is), then you can achieve that from a single SX, using only 11 port bits. In fact that will drive any one of 110 LEDs. You also could vary the brightness of each one.

    If you used all of the port bits of an SX28, you could drive any one of 380 individual LEDs.

    Cheers,

    Peter (pjv)
  • kingspudkingspud Posts: 128
    edited 2006-05-04 16:12
    Hi Peter,

    In actuality I would like to be able to control 100 or more LEDs.· I would like to control each one separately and yes I would like to be able to change the intensity of the light!· I am trying to create a board display that would act similar to a banner board and/or a bright-lite game!· Plus be able to scroll through each light and turn it on or off to make pictures on the board display!

    How is it possible to control each one of the individual 100+ LEDS with one SX28?

    Please explain?

    Thanks

    ·
  • DigitalDjDigitalDj Posts: 207
    edited 2006-05-04 22:56
    How about 192 leds or 64 RGB with 16 steps of PWM which gives you 4096 colors and you can hook at least 4 of these boards to a single SX28 by I2C communications·or can be used as a input/ouput expander without the PWM?

    Kevin




    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Education And Experience Teaches Knowledge Not Arrogance ! (Unknown)
    The Only Stupid Question Is The One Not Asked ! (Unknown, of coarse this is something that i would say)
    Do Not Burn The Bridge That Has Brought You Forth You May·Need To Journey Back ! (Chinese)


    Post Edited (DigitalDj) : 5/4/2006 11:01:28 PM GMT
  • kingspudkingspud Posts: 128
    edited 2006-05-04 23:14
    Yes... YES!!!!

    Please tell me more!

    Joe
  • DigitalDjDigitalDj Posts: 207
    edited 2006-05-05 00:47
    Paul Baker and I are working on the circuit. Paul has the PWM board done and ready to be made. The circuit uses the Max7313 which has 16 outputs for PWM. The circuit board will have 12 of the 7313's and associated components. The Max7313's supply voltage is 3.3volts and the outputs are current sink and can handle up to 5.5volts to the leds. The boards are also setup for the current limiting resistor packs whatever values the user needs. The outputs can run leds directly with a maximum current of 20ma per output. I have attached the link to the chip. I will need to talk to Paul on the status of the project and our intentions on the circuit boards for sale. The board does not include provisions for the microprocessor it is only a PWM/16 port I/O expander board, you will have to use your own processor.

    http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4101

    I·will be·using this circuit and a SX28 to control 2 grids of 64 RGB leds. I attached a photo link for you to see my prototype. These will go in my jukebox project which is pictured with my post.

    http://pg.photos.yahoo.com/ph/adigitaldj1@sbcglobal.net/album?.dir=4ea5scd&.src=ph&store=&prodid=&.done=http%3a//photos.yahoo.com/ph//my_photos
    ·

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Education And Experience Teaches Knowledge Not Arrogance ! (Unknown)
    The Only Stupid Question Is The One Not Asked ! (Unknown, of coarse this is something that i would say)
    Do Not Burn The Bridge That Has Brought You Forth You May·Need To Journey Back ! (Chinese)


    Post Edited (DigitalDj) : 5/5/2006 12:50:23 AM GMT
  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-05-05 01:44
    Im sure something can be worked out, but Im not going to give any estimate of cost or when it would be availible at this point, its too soon to get a full grasp of it. Material costs could be estimated, but I dont know what the man hours for assembly will be. We could work out a PCB only deal at this point, and could provide it once the design has been tested. But I wouldn't suggest it if you dont already have assembly experience, everything is surface mount with parts as small as 0402 (about the size of a grain of sea salt).

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    1+1=10

    Post Edited (Paul Baker) : 5/5/2006 2:01:43 AM GMT
  • kingspudkingspud Posts: 128
    edited 2006-05-05 17:54
    Hummmm... Interesting premise!
    I will keep an eye out on your project but, "about the size of a grain of sea salt" this is too much for me!

    Thanks for the info!

    Anyone else worked with multiple decoders in a sequence programmed by an SX28 chip to control 100+ LED's??? If so I would love to hear from you!!

    Joe
  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-05-05 18:04
    Sorry, a bit of miscommunication. The board itself is 4"x1.25", I designed it with the idea I would be assembling 3-4 of them for DigitalDJ and I. Since I have the equipment and experience, I didn't shy away from using really really small components on it. We could probably work out something that you can get a fully assembled board as well, but I can't provide what the price would be because I haven't assembled one yet. I estimate a couple hours/board for soldering, another to continuity test, another half hour for repair work, and another half to test it, or about 4 hours/board. But this is only an estimate, a ballpark figure would be around $100 for a board with 60-70% of this the cost of materials. This would not include the cost of a regulated 3.3V power supply, the LEDs or the connection wires connecting the board to the LEDs (the LEDs are off-board).

    Here's a pic of the board:

    attachment.php?attachmentid=40946

    The seperate top and bottom layers are in attachments in this thread: http://forums.parallax.com/showthread.php?p=576794

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    1+1=10

    Post Edited (Paul Baker) : 5/5/2006 6:13:45 PM GMT
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