Well I am fairly new to Arduino, but I have a little familiarity with electronics and things of that sort.
Before I go back to school, I want to make a police style LED lightbar for my room.
I plan to use 64 single color LEDs. I will have 8 arrays of 8 LEDs.
Basically my questions are:
Can the Arduino Duemilanove control this many LED's?
Instead of having the Arduino on USB all the time, Can I remove the USB and use the wall adapter? If I can, how do I toggle the light patterns? Is it that button on the board? Can I extend that button and put it on my enclosure?
Also, I am assuming that I will need 9v DC LEDs right?
And resistors, is there any specific type I would need?
I'm a newb also, so take this all with a grain of salt.
You will need to look into using an LED matrix. I haven't done it, but I have seen examples with more than 64 lights. There is probably an example in the hardware interfacing section.
So yes, given the time, effort, and skill. The board "should" be able to turn on and off the leds in some pretty manner.
I believe that the Duemilanove has a power outlet, you would use some type of wall outlet... 9v 650ma is the one that I have.
You shouldn't need to use the button on the board, it's only for reset.
If you want to have some type of button interaction, you would need to program some of the pins for that.
Connecting to the computers use isn't really for controlling your light display. Although, I'm assuimg it could through serial inputs while it was running. You use the usb to program your board.
i.e.
Forever Loop
If pin1 = high
pause
then set pin1 = low.
pause
There are alot of examples on the site and the main hardware site.
As for the LED's, unless you are using some external power source and a driver. The arduino can only put out 5v on a pin. My led's are 3.3v so without a resistor between there. You make smoke.
You would use a resistor voltage calculator to figure out the needed resistors based on the input parameters.
i want to do the same thing,but have no idea how to calculate the resistores value for a matrix,and the output pin's suply max 40mA and I guess it might be risky getting more current for exmaple 60 mA for 3 LED's?and for running a 8x8 matrix arduino has enough pins then using shift registers seems extra works!?
If you want to drive a matrix safely then use a MAX7221, this will drive one 8X8 matrix and you can chain them together to get more. With this IC you don't need resistors because current limiting is built into the chip.
see:- http://www.arduino.cc/playground/Main/LEDMatrix
to controll many led's from few pins..