Im having some trouble figuring out a logic problem
I can easily contorl a RGB LED with 3 potentiometers. Each pot controls one of the color with a value between 1-255.
However, im not sure how i could make a RGB LED cycle thru all the colors using a single Potentiometer.
It would be even better if i didn't have to use a arduino.
The goal is to make a RGB Reading Lamp. So the less components the better. If i have to use an arduino ill probably add some nifty sensors, like Light sensor and proximity sensor.
If you want one pot to manage three diodes, then you'd somehow need three different current values - a problem.
If you use the Arduino, then you're actually using the pot value to display one of the possible 256 x 256 x 256 (or 16,777,216) combination of the colors (in reality, short and long pulses to make the LEDs dim or bright). Of course, that's 256 color RGB values - you're not actually limited to how close you want each shade to be. Since the pot comes in with 0-1023 as allowable values, you're converting it into three ranges.
As a simple example, use this:
long i=AnalogRead(/* your pin */);
int r=(i>>7)&0x7; // 0-7 for red
int g=(i>>3)&0xF; // 0-15 for green
int b=i&0x7; // 0-7 for blue
Of course, as you turn the dial, blues would change much more often than reds...
It would be difficult to make all colors available with a single pot. But if I'm following the gist of your question, it sounds like you want a pot that varies hue in a HSI color model (keeping saturation and intensity constant, likely 100%). Essentially just moving around the outside edge of color wheel. Is that what you are hoping to do?
Do a google search or check out wikipedia for further info on converting between RGB and HSI color-space.
