Thanks you for your replies.
I have just realize that for attiny2313 the sketch will be too big. Attiny85 its perfect, I see that you can also use the 16MHZ internall oscillator.
Can someone point me to a basic schematic to use the Attiny85 ? I found something here (http://www.instructables.com/id/Use-a-1-ATTiny-to-drive-addressable-RGB-LEDs/?ALLSTEPS) but it only uses a 10uF capacitor and a resistor. Is this all it needs so that it can be operational ?
I am sorry if I have not mentioned this before but I am using the WS2811 led strips. I am wondering how many pixels can you operate on this little attiny85 ?