Hi !
My project is to build an RGB light like the Philips Living colors but cheaper and smaller while brighter.
The lamps will be connected together with 2.4 gHz modules (using nrf24l01 chips as they are incredibly cheap !!
(As it is my first post on don't hesitate to correct me if I did anything wrong on this post ! )
I've google a lot about mood lamp, high power leds (RGB, RGBA, RGBW...) and on led drivers. I found many very interesting projects. As I have limited number of instruments (understand no acces to an oscilloscope), I was looking for something easy to build. One project posted on instructables sum up all the differents stages to do an "Chained mood-light using high power RGB LEDs".
Which is basically that I have in mind, except for the remote control thing !
I get the different parts from Dx and ebay:
1x LED Cree XML RGBW (350mA)
4x 350mA Constant current regulated LED driver (PWM controllable) Recommendations For You - DealeXtreme
heatsink + thermal grease
and some nrf24l01+, arduino pro mini clone, jack connectors....
I: getting everything together
following the steps from instructables, I removed the 4 rectifier diodes on each driver, connected them together (in serie), and to the LED. I soldered a wire to the Dim pin on the PT4115 of each drivers, and didn't connect them to anything.
( PT4115 datasheet http://www.icdemi.com/manual/PT4115.pdf.pdf )
Powered by 12V DC converter, the led was very bright (more than I expected!).
II: Using PWM
The PT4115 allow PWM on its Dim pin at logic level (see datasheet or bottom of this post).
I connected the 4 "dimming wires" to pin D3 D5 D6 D9 of an Nano lying around (-> pwm pins).
I also connected the grounds together.
I used the fading code from the example (adapted to pin configuration), to see if I can get the red led to fade
/*
Fading
This example shows how to fade an LED using the analogWrite() function.
Created 1 Nov 2008
By David A. Mellis
modified 30 Aug 2011
By Tom Igoe
http://arduino.cc/en/Tutorial/Fading
This example code is in the public domain.
*/
int ledPin = 3; // RED led on D3
void setup() {
// nothing happens in setup
}
void loop() {
// fade in from min to max in increments of 5 points:
for(int fadeValue = 0 ; fadeValue <= 255; fadeValue +=5) {
// sets the value (range from 0 to 255):
analogWrite(ledPin, fadeValue);
// wait for 30 milliseconds to see the dimming effect
delay(30);
}
// fade out from max to min in increments of 5 points:
for(int fadeValue = 255 ; fadeValue >= 0; fadeValue -=5) {
// sets the value (range from 0 to 255):
analogWrite(ledPin, fadeValue);
// wait for 30 milliseconds to see the dimming effect
delay(30);
}
}
But It didn't work. I tried with other cables but got the same result.
I did try with other codes found on internet, but it didn't work ethier...
III: disassembly and reassembly
After re-checking every connections, I restart from zero, and I ended in the same situation.
So I google again about pt4115 problems, and found this in the datasheet : "A logic level below 0.3V at DIM forces
PT4115 to turn off the LED " so I grounded the dim pin, and it did nothing the LED was still bright.
As I'm working on a wood panel support by metal framework, I try to "smached" the cables on the framework. And somehow I managed to get some Leds ON OFF !! (not in areliable way, sometimes it work sometimes it didn't)
**IV: Help, Help, I need your help !! ** 
In a last try, I connected the red led's dimming cable to the digital input 3 through a pull down resistor (schematic at the bottom) (I'm not sure if this sentence make sense). And the red Led is now always turn off, even with pwm signal or setting the D3 as output High.
Any idea how to get this project working ?
It wasn't supposed to be such a pain !!
Any help is more than welcome !!
