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
    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
    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

    Senior Member

    Feb 17, 2010
  4. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    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.