Heya all, first, I am new to this stuff, so my understanding of the physics that drives all this is extremely limited.
Currently, I have a RGB LED (anode type) hooked up to my Arduino. The cathode is hooked up to the 5V and the anodes for each color in the LED is hooked up to PWNs 3, 5 and 6. (red, green and blue respectively).
Everything works as it should, however, I read up a lot about the need for resistors to prevent the LEDs from burning out.
My question is, how do I find out what kind of resistors I need to use? Is there a formula or calculator that I can use to determine this? What if I have multiple RGB LEDs that I want to hook up to my Arduino? (I'd like to hook up around 5 of these RGB LEDs, all performing the same function). I saw this thing called a breadboard, what is it? Do I need that to allow plugging in of more than 1 RGB LEDs?
Anyway, any links to tutorials or high-level diagrams would be much appreciated. Again, I'm new to all of this, and am trying my best to take things one step at a time, any help would be much appreciated.
Full brightness option requires you know the current they run at and the forward voltage. 300 ohms usully isn't too far out for small LEDs on 5 volts. The page you posted doesn't give values or a links to a data sheet.
You need one resistor for each cathode.
Do not run them without resistors, it stands as much chance of cooking the arduino as the LEDs without.
? One LED for three status indicators
? Pin 3 is red and pin 4 is green
The 5mm Triple Output RGB LED is red, green and blue colors LED. The 5mm Triple Output RGB LED units have four pins. There is one pin for each color and have a common anode. The one LED used as three status indicators or pulse width modulate and all three give mixed colors.
? Forward voltage (RGB): (2.0, 3.2, 3.2) V
? Luminosity (RGB): (800, 4000, 900) mcd
The arduino pins are rated at 40 mA max, most recommend you stay below 20mA so you should only run 1 LED per pin. If you went with 1k resistors as I suggested you would get away with 5 on each pin. But they would want one resistor per LED (3 on a RGB which is effectively 3 in one package). Since the red LED forward voltage is only 2 volts, you couldn't use a 100 ohm resistor on thet part of the RGB, current draw through the Arduino pins aside.
Basically 5 RGB Leds are 15 single Leds wich is above the arduino Current rating (correct me if i'm wrong) escpecially if you have a weak Mainboard or Laptop. The Arduino is a Microcontroller and I/O Board, not a Power-provider for Leds or motors.
You could use LED-Driver chips or use a rainbowduino.
I did a small test here (also note, the stuff i plugged the Leds into is big Breadboard) driving 36 RGB Leds from normal USB without resistors or any additional components than a Rainbowduino.
Thanks Apogee. The reason why I am powering it via USB is out of convenience because I am sending to the Ardruino a series of feedback representing the CPU load. The values would change the color of the RGB LEDs.
Thanks for the diagram! Its very helpful in understanding how it works!
Lastly, say I do need more voltage, if I have it plugged into the USB, can I plug the IDE connector into the 5V as well to get another 5V? Or is it one or the other only? Thanks again!!!