Arduino powered LED night sky

Hey guys,

I want to start a project that would be made up of some sort of frame that would hold a bunch of LEDs dangling at different distances to simulate stars. An Arduino would be used to assign different settings to the “night sky” (color change, twinkle speed, etc…) I would also like to be able to program the LEDs to form constellations.

How would you set up such a large number of LEDs to run on the Arduino? Since I want some of them to be able to be controlled very specifically (constellations) you would need a lot of them to be able to accept individual commands, correct? How would you expand the Arduino to include enough pins for so many LEDs?

Pretty new at this but trying to soak up as much as I can. Thanks for the help in advance.

/me

I wouldn't attempt to do it with one Arduino, or a bunch of Arduinos; instead, I would incorporate the intelligence into each LED (or possibly group of 4-6 LEDs), and use SMD versions of something like the ATTiny85 or such to control the LEDs, using I2C or SPI (some kind of 1/2-wire protocol) to communicate the settings to all of them along the bus...

Very interesting project but it is very big and quite ambitious. The problem you have is that if you have a large number of LEDs in order to light up a constellation as it moves through the sky. In fact so many that you end up looking at some sort of lap top screen. Then if you have a fixed night sky with LEDs in fixed places and fixed resistors to simulate the different star magnitudes there is not much for an arduino to do in controlling them. What sort of size are you thinking about?

Cool idea.

Some degree of simplification may be necessary, so what about using Grumpy Mike's suggestion of fixed resistors to set the relative brightness, but then control the overall brightness of a constellation using a PWM output driving a mostfet. That way, you could fade the constellations in and out. For star colour, you could use RGB LEDs, again with the right ratios of series resistors to get the colour you want when it comes up to full brightness.

If you use an Arduino Mega then you will have a lot of IO pins available.

How would you set up such a large number of LEDs to run on the Arduino?

You may need to use a PC: it’ll take a lot more memory than an Arduino’s to simulate bill-yuns and bill-yuns of stars ::slight_smile:

There are a few basic questions you need to answer before going any further with the design.

How many “stars” will you have in your simulation?

Do want want to be able to “twinkle” all of them? Or only some?

Is it okay to just flicker them “on” and “off” for twinkling? Or do you want vary them at multiple levels?

When you’re highlighting stars for constellations, is it okay to just make them brighter in a single step? Or do you want to “fade” them between brightness levels?

You can do things a lot cheaper if you do them in the simpler fashion. You may also find that fancier control of a really large number of LEDs exceeds the capacity of a humble Arduino because of the large volume of data involved.

I think previous posters guessed you wanted to set up a funtional planetarium of some sort...but it sounds like you want to set up fixed stars and then manipulate them from the Arduino, correct?

I have some small, adressible LEDs here: http://www.bliptronics.com Along with a library to control them.

Nice idea for a project, it would look pretty good I think as the LEDs are a very small point source they do indeed look quite like stars when viewed straight on.

It would be pretty easy to hookup, if I understand you correctly. You could implement twinkling, brightness, colors etc and turn constellations on/off and so forth.