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LED Display - Questions! — Parallax Forums

LED Display - Questions!

GeorgeGGeorgeG Posts: 5
edited 2008-01-11 11:25 in Learn with BlocklyProp
Hi there,
I'm planning to build a "simple" LED Display, although I have some questions that need to be answered.
First of all, I'm gonna use 64 (red, or maybe blue) LEDs.

PLAN 1:
Use one 74HC164(N) to control 8 74HC374(E) that control 8 LEDs each.

PLAN 2:
Use another "controller" (74HC164) that has more outputs (more than 8, maybe 64 if that exists smilewinkgrin.gif)


Whats your opinion, or what else can I do?
Thanks in advance!

Comments

  • GeorgeGGeorgeG Posts: 5
    edited 2007-12-21 14:18
    Ok, I just realised that I posted this in a wrong section :P
    Maybe a MOD can move it please? [noparse]:([/noparse]
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-12-21 15:26
    George,

    Not sure where you intended to post this message since it makes no mention of a BASIC Stamp, SX or Propeller microcontroller. The ‘controller’ you mention is actually a parallel to serial shift register. It’s unclear from your post how you plan to interconnect these device. 64 LEDs can easily be controller (including brightness) from a single MAX7219 IC or an array of 74HC595 chips (without brightness control).

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
  • GeorgeGGeorgeG Posts: 5
    edited 2007-12-21 15:47
    Yeah, sorry.. Im gonna use a BS2.
    Im gonna make the Display show different things.. [noparse];)[/noparse]
  • Mike GreenMike Green Posts: 23,101
    edited 2007-12-22 21:10
    There's also a TPIC6595 which works like a 74HC595, but includes MOSFET high current drivers.

    There are several Nuts and Volts columns on Parallax's website that demonstrate the use of various
    I/O extenders with Stamps. They're all downloadable. The StampWorks manual is also downloadable
    and has a section on the use of the 74HC595.

    www.parallax.com/Resources/NutsVoltsColumns/tabid/272/Default.aspx

    www.parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/txtSearch/stampworks/List/1/ProductID/144/Default.aspx?SortField=ProductName%2cProductName
  • deSilvadeSilva Posts: 2,967
    edited 2007-12-25 17:57
    George, how do you like this?
    http://forums.parallax.com/showthread.php?p=696682
    It was built for the Propeller, but that is of little importance, as the program can be adapted to any processor
  • Oper8r AlOper8r Al Posts: 98
    edited 2007-12-30 06:42
    Just wondering if there is any chance of someone adapting the project deSilva mentions to SX or Stamp. I am Just starting to work with the SX
    and thought this would be a great project. If not I will put it on the back burner until I am able better understand the spin code myself.

    Thanks,
    Al
  • deSilvadeSilva Posts: 2,967
    edited 2008-01-10 23:35
    The basic program is simplicity itself. You "normally" select and LED to be set in a matriux by a column (+) and a row (-).
    Charlieplexing arranges the LEDs in a way so you can also set a column (-) and a row (+),
    reducing the number of needed pins from - say - 8+8=16 for 64 LEDs to 9 (which would even cover 72 LEDs)
    The drawback is that it is quite tricky to use current amplifiers, as they have to have three states.
    The Propeller has the advantages that ALL its pins can - in principle - source and sink 50 mA which is fine
    for multiplexing 64 superbright LEDs without any resistors (and even exceptable for standard LEDs...)

    And "scrolling text" is a program of its own of course...
  • T&E EngineerT&E Engineer Posts: 1,396
    edited 2008-01-11 11:25
    Take a look at my posting (T&E Engineer) for some related LED display projects I have built on both the BS2 and SX.

    http://forums.parallax.com/showthread.php?p=684565
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