Depends on what you want the leds to do. If you simply want them to shine when buttons are pressed, dont waste arduino code on that. But if you want them to blink or react to the controller state (hence code) they'll have to be controlled via some digital pins (in output state) as Goyard stated, as thus you are requesting more pins (maybe the mega as I say in my first message).

Althought: multiplexing LEDs is very easy. 3 outputs can control 8 leds and so forth. But more coding/control effort.

On Sun, Apr 10, 2011 at 3:12 PM, Charles Goyard <cg@fsck.fr> wrote:
Pierre Massat wrote:
>
> I also saw that the board could power LEDs. This could be very interesting,

Yes, but the Digital Input are "shared" with the digital outputs. So if
you put a button on a line, you cannot put a led too. You have up to 12
inputs/outputs IN TOTAL. You choose in your program if you want
something to be a input or an output.

Given your questions (no offense), I would go with a Mega board and not
bother with multiplexing yet. That way you get a fully assembled,
ready-to-use 50 inputs/outputs for your leds and buttons, + 16 analog
inputs, with plenty of program space.

--
Charles

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Pedro Lopes (MSc)
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