HC12 - Multiplexing 4 x 7 segment displays

Thread Starter


Joined 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.


Joined 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.


Joined 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.