Using Potentiometers to Control LEDs

Description

This lab uses 2 potentiometers to control 3 LEDs

Components Used

2 potentiometers

3 LEDs

3 resistors

Arduino Code

/*
* "Coffee-cup" Color Mixer:
* This program controls 3 LEDs with 3 potentiometers. One potentiometer controls two LEDs, the other controls one LED.
*/

// Analog pin settings
int aIn = 1;    // Potentiometers connected to analog pins 0, 1, and 2
int bIn = 2;    //   (Connect power to 5V and ground to analog ground)
//int cIn = 2; 

// Digital pin settings
int aOut = 9;   // LEDs connected to digital pins 9, 10 and 11
int bOut = 10;  //   (Connect cathodes to digital ground)
int cOut = 11; 

// Values
int aVal = 0;   // Variables to store the input from the potentiometers
int bVal = 0; 
int cVal = bVal; 

// Variables for comparing values between loops
int i = 0;            // Loop counter
int wait = (1000);    // Delay between most recent pot adjustment and output

int checkSum     = 0; // Aggregate pot values
int prevCheckSum = 0;
int sens         = 3; // Sensitivity theshold, to prevent small changes in
                      // pot values from triggering false reporting
// FLAGS
int PRINT = 1; // Set to 1 to output values
int DEBUG = 1; // Set to 1 to turn on debugging output

void setup()
{
  pinMode(aOut, OUTPUT);   // sets the digital pins as output
  pinMode(bOut, OUTPUT);  
  pinMode(cOut, OUTPUT);
  Serial.begin(9600);     // Open serial communication for reporting
}

void loop()
{
  i += 1; // Count loop

  aVal = analogRead(aIn) / 4;  // read input pins, convert to 0-255 scale
  bVal = analogRead(bIn) / 4;
  cVal = analogRead(bIn) / 4; 

  analogWrite(aOut, aVal);    // Send new values to LEDs
  analogWrite(bOut, bVal);
  analogWrite(cOut, cVal);

  if (i % wait == 0)                // If enough time has passed...
  {   
    checkSum = aVal+bVal+cVal;      // ...add up the 3 values.
    if ( abs(checkSum - prevCheckSum) > sens )   // If old and new values differ
                                                  // above sensitivity threshold
    {
      if (PRINT)                    // ...and if the PRINT flag is set...
      {
        Serial.print("A: ");        // ...then print the values.
        Serial.print(aVal);        
        Serial.print("\t");
        Serial.print("B: ");       
        Serial.print(bVal);
        Serial.print("\t");
        Serial.print("C: ");               
        Serial.println(cVal);
        PRINT = 0;
      }
    } 
    else
    {
      PRINT = 1;  // Re-set the flag  
    }
    prevCheckSum = checkSum;  // Update the values

    if (DEBUG)   // If we want debugging output as well...
    {
      Serial.print(checkSum);
      Serial.print("<=>");
      Serial.print(prevCheckSum);
      Serial.print("\tPrint: ");
      Serial.println(PRINT);
    }
  }
}

Image

(also see attached lab3.jpg) 

Board with LEDs and pots