Driving many LEDS with timer

Hello All!

This is my first post on this forum. Bought my Arduino starter kit yesterday. I have a project I've been working on with a raspberry pi which is a linear clock with leds showing time. It is supposed to be used at the pre-school where I am working so the kids can see how much time there is left until for example lunch, snack or song gathering.

The problem I had with raspberry was that it was a computer, well.. That's not a problem. But I don't see why I would need a grand operating system like Rasbian to controll my leds and rapsies are also pretty costy considering I don't need most of the "bells and whistles".

So. I have an Arduino, I have LEDS. But since I am pretty much a total beginner at Arduino I don't really know which extra parts I need to controll all the LEDS I want to use.

What I want to do: Controll at least 20 LEDS individually depending on the time of the day. When pre-school opens at morning = all LEDs are HIGH Then every half hour one LED goes LOW etc.

Question (if it was to much text above): Which parts do I need to acheive this? The code I can learn through reading books and online. But in order to experiment my way forward in the project I want all parts availible in my home.

Thank / Henrik

Your toddlers would love NeoPixels. The depth of your pockets is the limit. http://www.adafruit.com/category/168 Leo..

If I read you right, you want a 10 hour countdown, that clicks ever half hour. You want it to know when pre-school opens in the morning, and then start it's count down.

I don't really understand. I suspect that pre school does not run for 10 hours. Now you have me curious. What is the application for?

my question is if you can do an UNO, no external shift registers or port expanders

thinking a 5x5 charlie plex ?

You could use an Arduino (Uno), Max7219, and up to 64 LEDs pretty simply.
This MAX7219 breakout board brings out 2 pins to connect to each LED, your programming only has to write to the 8 data registers and not be involved in the multiplexing.

And this picture showing some LEDs connected up with 30 AWG wirewrap wires.

[quote author=jack wp link=msg=2389463 date=1441754913] I don't really understand. I suspect that pre school does not run for 10 hours. Now you have me curious. What is the application for? [/quote]

The pre-school is open from 7:00 to 17:00. And the purpose of the clock is to give the children help with understanding the concept of time.

have look at the Neopixels, e.g. at this project: https://forum.arduino.cc/index.php?topic=346884.0

They are easy to connect and to program using the FastLED library, You can use rings, strips or single LEDs.