4 pins using 4 PWM pins?! - LED strip

[Dbergy9]

Hi,

I just bought this LED strip on ebay.

http://www.adafruit.com/products/306

I see that it uses a 4 pin JST SM plug to connect it to a microcontroller but does it need 4 pwm pins? My Atmega328 microcontroller is coming in soon but it only has 6pwm pins as far as I know and I need more than 2 pins left idle...

Anyone?

Thanks for your help in advance.

[nick_12]

No sir each LED is individually addressable that is done by a serial protocol called SPI. It would use the 2 spi pins from your microcontroller and 2 power pins. If you going to use it for high brightness your going to need a external power supply of 5 volts and at least 2 amps. If you have any more questions feel free to ask. I am no professional, but I read a lot.

[Dbergy9]

Hey, thanks for the reply.

I've attached a document with the pins list on the microcontroller, which ones exactly would you use on this do you know?

[Dbergy9]

Sorry here it is...

[adafruit_support_mike]

That would be 11, 12, and 13.

[tldr]

you should probably check your ebay leds to make sure that they really are the same as the adafruit strip. there are strips available that use a number of different chips. if indeed your strip does have lpd8806 chips, there are some strips that connect 6 leds per chip, so that they light up in groups of three. a friend of mine recently got some strips on which the order of the colors was different.

if you do have an lpd8806 strip, you only need to connect pins 11 and 13 since communication with the strip is in one direction only.

looks like you've got a bunch of spi devices. the led strip has no ~cs, so every time you write to sd or ram or the ethernet, you'll also be writing to the leds. maybe you can rig some sort of diode and gate with the spi clock and another output pin.