For background see my original post. I've decided to not to use batteries and have it wired up with wall power.

I wish to use the Arduino Pro Mini 5V as the controller for my diorama project. I have five completed buildings which will all have LEDs (with only two wired up so far). The two currently wired buildings have multiple "zones/rooms" that can have its LEDs activated separately.

Building 1 is a saloon with rooms above. It has a total of 7 zones/rooms.

Building 2 is a store with a doctor's office above and rooms in the back of each. It has 4 rooms.

With this setup, I am able to use the software to simulate people coming and going within the rooms. It's pretty neat.

However, I'm currently at 11 outputs out of the Mini. I'm running out of pins. How can I have more outputs?

1 Answer 1


I think I understood what you want. If you want to control more LED's with less pins, consider using a shift register. For example, sn74hc595 could increase your digital outputs drastically. It has 8 bits, so you can have 2^8 combinations of outputs with it! For example, 0000 0001 is something, and 0000 0010 is something else, and so on. Check it out! I hope this helps :)

https://learn.sparkfun.com/tutorials/shift-registers - Basic knowledge about shift registers http://www.bc-robotics.com/datasheets/sn74hc595.pdf Other shift registers are great as well

  • This looks like it might solve my problem. Let me completely read it before marking this as the correct answer.
    – EL MOJO
    Apr 26, 2017 at 13:42
  • Will I be able to use Pulse Width Modulation with a shift register?
    – EL MOJO
    Apr 26, 2017 at 14:03
  • I have never used them in that way, here is an article, perhaps you find your answer there forum.arduino.cc/index.php?topic=8183.0
    – user33153
    Apr 26, 2017 at 14:26
  • Very cool. Looks like I'll be buying some more parts and trying some stuff out.
    – EL MOJO
    Apr 26, 2017 at 14:30

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