Brettr12321:
The RGB LED strips i have are the analog neo pixel led strips from adafruit. I need to have three led strips each being a meter long and be able to change the color of each strip individually. i realize now that i should have bought digital rgb strips but its too late now. i just need to know if its possible to control 3 led strips each being a meter long individually with the led controller. if not im probably just going to have to buy digital strips.
Neopixels that are analog??? Huh: I guess so.
If you want to controll all four channels, then you need 12 PWM outputs. An arduino UNO has 6. hence the need for this pca9685 thingy.
The SCL and SDA connections tell me that this thing is an I2C board, which is great. The LED strips are common-anode. You apply +5v to the common, then either connect each led wire to one of the PWM outputs of the pca9685 (which will reverse the brightness you get), or (better) hook up a driver chip like the ULN2003A (you'll need 2). The ULN2003A outputs are grounded when the input is high, which is what you want, and they will easily handle the power.
The problem then becomes: how do you talk to the pca9685? Well, you install the adafruit pca9685 library, and look at the examples.
Personally, I'd install the library, connect the SDA and SCL of the pca9685 to the appropriate pins (I think it's A4 and A5 on the UNO, and don't forget ground and power), spark up one of the examples, and just stick an LED (with a current-limiting resistor!) on a couple of the PWM output pins.
Once you can drive an LED, it's time to connect the 12 pca9685 outputs (3*RGBW) to the inputs of a ULN2003A (you'll need 2 - they have seven channels each). Attach an LED between +5v and the ULN2003A output to confirm it all still works. Finally, attach the real RGB strips to power and the ULN2003A. Wiring it up is simpler than using it to drive solenoids because you don't need to worry about flyback. All you really need is power, ground, and the inputs. You can have a separate power supply for the LED strips if you want, provided that all the grounds are connected.
From that point, it's a matter of programming up what colours you want.