HC12 - Multiplexing 4 x 7 segment displays

Discussion in 'Embedded Systems and Microcontrollers' started by Zaraphrax, Mar 23, 2010.

  1. Zaraphrax

    Thread Starter Active Member

    Mar 21, 2009
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    3
    Hi all,

    I've been looking around the web at multiplexing 7 segment displays, and I'm not sure what I want.

    I have a HC12 microcontroller, and need to drive 4 7 segment displays from it. I don't want to use 28 I/O pins, because my assignment specifies a lot of other I/O devices that I need to connect. I'm using the 7 segment displays to show set-points, which the operator will adjust using a keypad.

    As I understand it, multiplexed arrays are harder to program, which is isn't very useful if that's the case because I want to keep the eventual program as simple as possible.

    I'm a little lost on how exactly I need to connect everything to get it multiplexed. Or, should I just use 4 BCD-7 seg converters like a 7447 to drive them? Programming wise that would be a lot easier, and I'd only use 16 I/O pins on the controller instead of 28.

    Any help is greatly appreciated.
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    If you are displaying numbers, you can use 1 pin to send a decoder/7 seg display IC the number and it will properly light the leds.
     
  3. hspalm

    Active Member

    Feb 17, 2010
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    8
  4. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    1,015
    69
    The few lines of code you need to drive a multiplexed display are relatively trivial.

    If you ever intend to do any serious programming, the display code should be an easy start.
     
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