Can't Figure out RGB LEDs... embarassing, heh...

Forum 2005-2010 (read only) Hardware Interfacing
#1

Hey guys,

So, this is week one with the Arduino for me. I ran through a number of simple tutorials online, then I went through the Getting Started with Arduino book. I had no problems whatsoever, but when I got to the end of the book, it makes the suggestion to change the final project… a three LED lamp… from three LEDs to a single RGB LED.

It just so happened that I had a few, so I set about trying this out. Somehow or another, I’m just not understanding things.

Here’s how I have it setup

1 3 and 4 on the RGB LED are wired from 330 Ohm resistors to digital pins 9, 10 and 11. 2, the longest, is wired to ground.

My sketch looks like this:

int RED = 9;
int GREEN = 0;
int BLUE = 11;

void setup()
{
pinMode(RED, OUTPUT);
pinMode(GREEN, OUTPUT);
pinMode(BLUE, OUTPUT);
}

void loop()
{
for(int r = 0; r < 1024; r+=5) {
for(int g = 0; g < 1024; g+=5) {
for(int b = 0; b < 1024; b+=5) {
analogWrite(RED, r);
analogWrite(GREEN, g);
analogWrite(BLUE, b);
delay(30);
}
}
}
}

I have no idea why this wouldn’t work. I can’t figure out how to dumb it down from here either. I know the LEDs work because, if they’re wired to ground and I touch one of the color poles, it faintly lights up.

Sorry for the stupid question. I just refuse to accept defeat from something as simple as this.

#2

Doh, yes it should be. I had switched them around earlier and missed that.

You just figured it out for me. I didn't realize it could be common anode or common cathode. Applying 5v to the pin I assumed was a common ground and grounding the others instantly brought it to life.

Phew. Thought I had been beaten, haha.

Thanks a ton for your help.

#3

you properly tested the rong way

common anode or common cathode (common + or common -)

have a look in the led is it clear can you see the a pin that is other then they others… (mostly one of the 2 middle pins) then the single one beside it is red the other to are green and blue :stuck_out_tongue:

hope you can figure it out now :stuck_out_tongue:

note:
I always plug it directly to the board on pins 3,4,5 and 6
4 being HIGH or LOW depending what kind of led it is :smiley:
3,5 and 6 are pwm
Don’t them on to long! use 220R resistors for that this is just for testing.

#4

Here’s something interesting to try with your RGB LED. Basically it flashes the LED a specified color that you make with 3 potentiometers.:

int ledRGB = {9, 10, 11};

int potenVal1 = 0;
int potenVal2 = 0;
int potenVal3 = 0;

byte myColor = {potenVal1, potenVal2, potenVal3};

void setup(){
for(int i = 0; i < 3; i++){
pinMode(ledRGB*, OUTPUT); //Set the three LED pins as outputs*

  • } *
  • setColor(ledRGB, BLACK); //Turn off led*
    }
    void loop(){
  • changeLuminosity();*
  • flashOneColor(ledRGB, myColor);*
    }
    void setColor(int* led, byte* color){
  • for(int i = 0; i < 3; i++){ *
    analogWrite(led_, color*);
    }
    }
    /changes luminosity and color of an RGB LED/
    void changeLuminosity(){
     //analog input pins to read potentiometer voltages from*
    * int potenIn1 = 7;
     int potenIn2 = 6;
     int potenIn3 = 5;*_

* //read the voltage on the potentiometer pins and scale these to a range of 0-255 (common anode)*
* potenVal1 = 255 - (analogRead(potenIn1)/4);*
* potenVal2 = 255 - (analogRead(potenIn2)/4);*
* potenVal3 = 255 - (analogRead(potenIn3)/4);*

* //write color values to LED pins*
* analogWrite(ledRGB[0], potenVal1);*
* analogWrite(ledRGB[1], potenVal2);*
* analogWrite(ledRGB[2], potenVal3);*

* //save color created by user in color array myColor[]*
* myColor[0] = potenVal1;*
* myColor[1] = potenVal2;*
* myColor[2] = potenVal3;*
}

#5