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HW 3: 3-pot LED control and rainbow maker

jennifer_wang's picture
Mon, 09/19/2011 - 17:58 — jennifer_wang

Description:

I created the 3-pot LED control circuit and used the given code in the lab for controlling the brightness of each LED with each pot.

As an optional part, I created what I call a "Rainbow Maker" by using one pot to control the 3 LEDs so that it fades from red to green to blue to red.

Components used:

  • red LED
  • green LED
  • blue LED
  • 3 potentiometers
  • 3 220 ohm resistors

Code:

/*
* Rainbow Maker
* Jennifer Wang
* September 14, 2011
*
* Control 3 LEDs with 1 potentiometer, blending colors in a rainbow from red
* to orange to yellow to green to blue to indigo to violet back to red
*
*/
 
int potPin = 2;   // select the input pin for the potentiometer
int redPin   = 9;   // Red LED,   connected to digital pin 9
int greenPin = 10;  // Green LED, connected to digital pin 10
int bluePin  = 11;  // Blue LED,  connected to digital pin 11
int val = 0;      // variable to store the value coming from the sensor
int redVal = 0; // calculated value of red LED brightness
int greenVal = 0; // calculated value of green LED brightness
int blueVal = 0; // calculated value of blue LED brightness
 
void setup() {
  Serial.begin(9600);
}
 
void loop() {
  val = analogRead(potPin);    // read the value from the sensor, between 0 - 1024
  Serial.println(val);
  // NOTE: coefficients of linear equations to determine LED brightness are rounded,
  // so border values are explicitly set
  
  // 1024/7 colors (ROYGBIV) = 146
  // red when val == 0 (red LED only)
  // orange when val == 146
  // yellow when val == 292
  // green when val == 438 (green LED only)
  // blue when val == 584
  // indigo when val == 730 (blue LED only)
  // violet when val == 876
  // red when val == 1024
  
  // from red to green
  if (val >= 0 & val < 438) { 
    redVal = 255 - 255/438.0*val;
    greenVal = 255/438.0*val;
    blueVal = 0;
  }
  // green
  else if (val == 438) { 
    redVal = 0;
    greenVal = 255;
    blueVal = 0;
  }
  // from green to indigo
  else if (val > 438 & val < 730) { 
    redVal = 0;
    greenVal = 637 - 255/292.0*val;
    blueVal = -382 + 255/292.0*val;
  }
  // blue indigo
  else if (val == 730) { 
    redVal = 0;
    greenVal = 0;
    blueVal = 255;
  }
  // from indigo to red
  else if (val > 730 & val < 1024) { 
    redVal = -633 + 255/294.0*val;
    greenVal = 0;
    blueVal = 888 - 255/294.0*val;
  }
  // back to red
  else if (val == 1024) { 
    redVal = 255;
    greenVal = 0;
    blueVal = 0;
  }
  analogWrite(redPin, redVal);
  analogWrite(greenPin, greenVal);
  analogWrite(bluePin, blueVal);
  
  Serial.println();
  Serial.println(redVal);
  Serial.println(greenVal);
  Serial.println(blueVal);
  Serial.println();
}
3 pot LED control circuit
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