hello: I want to made a matrix composed by 500 LED and command it with an arduino UNO, the problem is that arduino uno has only 13 pins, so what should i do in this case. thank you :)
Use several shift registers and use the ShiftPWM library http://www.elcojacobs.com/shiftpwm/
Or use Neopixel strips:- http://www.adafruit.com/product/1460
ameurbilel: I want to made a matrix composed by 500 LED and command it with an arduino UNO, the problem is that arduino uno has only 13 pins, so what should i do in this case.
arduino uno has only 13 pins
Uno has 20 pins - D0-D13, and A0-A5 which may also be used as D14-D19. So 20.
What kind of matrix? Single color? Say 24 x 24 (576)? Can use 9 0f 8x8 LED matrix, 9 x 64 = 576 LEDs. Use MAX7219 based modules, daisy chain together, and control from parola.h library.
Just 3 pins to control them all. SCK, MOSI, SS. SCK & SS go to all devices, Serial data is passed along. Each has 8 registers to write to, each register controls 8 LEDs in a matrix.
500 WS2812 LEDs will need a lot of power - up to 60mA (with all 3 colors on) per LED x 500 = 30A. Nice & bright tho.
MAX7219 only has 8 LEDs on at a time (out of 64), so 160mA x 9 = 1.44A. It multiplexes at 800 Hz for flicker-free viewing.