Lab 2: Digital I/O with Arduino Boards + Diffuser

Assignment: Digital I/O with Arduino Boards + Diffuser

Collaborators:

Description:

A project that uses the Arduino board and programming environment to demonstrate how to simulate fading of multiple LEDs using Pulse Width Modulation.

Components List

Red, Green, and Blue Light Emitting Diodes
220 Ohm Resistor X 3
Arduino board
7 Wires
One Travel Sized Advil Bottle (empty)
Power came from computer via USB Cable

Notes:

During the class period, I uploaded the assignment sample code that allows for user input through the serial port. I use a Linux operating system, and I found that cutecom was a great application to send commands to the serial port (as an alternative to the Arduino serial monitor). After I found a decent diffuser, (a perfectly sized Advil travel bottle) I used Clay Shirky's cross-fading PWM code with a delay of 5 milliseconds to make a more interesting light display.

Diffuser Board

Code used in this Assignment:

/*
* Code for cross-fading 3 LEDs, red, green and blue, or one tri-color LED, using PWM
* The program cross-fades slowly from red to green, green to blue, and blue to red
* The debugging code assumes Arduino 0004, as it uses the new Serial.begin()-style functions
* Clay Shirky <clay.shirky@nyu.edu>
*/

// Output
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

// Program variables
int redVal = 255; // Variables to store the values to send to the pins
int greenVal = 1; // Initial values are Red full, Green and Blue off
int blueVal = 1;

int i = 0; // Loop counter
int wait = 5; // 5ms (.005 second) delay;
int DEBUG = 1; // DEBUG counter; if set to 1, will write values back via serial

void setup()
{
pinMode(redPin,   OUTPUT);   // sets the pins as output
pinMode(greenPin, OUTPUT);
pinMode(bluePin, OUTPUT);
if (DEBUG) {           // If we want to see the pin values for debugging...
Serial.begin(9600); // ...set up the serial ouput on 0004 style
}
}

// Main program
void loop()
{
i += 1;      // Increment counter
if (i < 255) // First phase of fades
{
redVal   -= 1; // Red down
greenVal += 1; // Green up
blueVal   = 1; // Blue low
}
else if (i < 509) // Second phase of fades
{
redVal    = 1; // Red low
greenVal -= 1; // Green down
blueVal += 1; // Blue up
}
else if (i < 763) // Third phase of fades
{
redVal += 1; // Red up
greenVal = 1; // Green low
blueVal -= 1; // Blue down
}
else // Re-set the counter, and start the fades again
{
i = 1;
}

analogWrite(redPin, redVal); // Write current values to LED pins
analogWrite(greenPin, greenVal);
analogWrite(bluePin, blueVal);

if (DEBUG) { // If we want to read the output
DEBUG += 1; // Increment the DEBUG counter
if (DEBUG > 10) // Print every 10 loops
{
DEBUG = 1; // Reset the counter

Serial.print(i);       // Serial commands in 0004 style
Serial.print("\t");    // Print a tab
Serial.print("R:");    // Indicate that output is red value
Serial.print(redVal); // Print red value
Serial.print("\t");    // Print a tab
Serial.print("G:");    // Repeat for green and blue...
Serial.print(greenVal);
Serial.print("\t");
Serial.print("B:");
Serial.println(blueVal); // println, to end with a carriage return
}
}
delay(wait); // Pause for 'wait' milliseconds before resuming the loop
}

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