Assignment: Input / Output Coincidence Lab Assignment
Collaborators:
My idea for this lab was revolved around this great little series of flipbooks called Schadenfreude, defined on the back of the book as:
Noun - Pleasure derived from the misfortune of others
Origin: German, from Schaden 'harm' + Freude 'joy'
Each flipbook illustrates an instance of small embarrassment or misfortune; in the one I selected, while a man is carrying a television on his shoulders with both hands, his pants slowly fall down.
Due to the nature of a flipbook, the reader/viewer must constantly exert pressure on the book in order to flip the pages rapidly enough for the images to "move." I thought it would be a great way to employ the FSR, taping it to the back cover where the fingers push onto the book. I wanted to have the pressure exerted correspond to the Piezo speaker, which is especially appropriate, due to its tinny, almost cruel sound output. I began with the given Theramin code, substituting the photocell for the FSR. This worked, but I had to press the sensor incredibly hard to get a sound out of the Piezo. With some help, I found out that this must be a problem of range, so I looked around at previous classes' codes for help. Ryan Kaufman's "Light Flute" from 2008 was closest to what I was attempting to do, so I amended his code (I am not using a photocell) & ran this:
int fsrPin = 0; // select the input pin for the FSR
int speakerPin = 7;
int fsrval = 0;
void setup() {
pinMode(speakerPin, OUTPUT);
Serial.begin(9600);
Serial.println("ready");
}
void loop() {
if (fsrval < 150); // set threshold value on FSR for program to proceed.
Serial.print (fsrval); // read input.
digitalWrite(speakerPin, LOW);
for( int i=0; i<500; i++ ) { // play it for 50 cycles
digitalWrite(speakerPin, HIGH);
digitalWrite(speakerPin, LOW);
}
}
This didn't really help! I fiddled for awhile longer, & couldn't figure out how to correctly calibrate the system. So, already handicapped, I thought of what I would like the system to be like even more ideally. It would be great if the sound the Piezo played corresponded in actual melody to the sentiment of the flipbook. I found this code on the Arduino website, & liked it:
/* Play Melody
* -----------
*
* Program to play a simple melody
*
* Tones are created by quickly pulsing a speaker on and off
* using PWM, to create signature frequencies.
*
* Each note has a frequency, created by varying the period of
* vibration, measured in microseconds. We'll use pulse-width
* modulation (PWM) to create that vibration.
* We calculate the pulse-width to be half the period; we pulse
* the speaker HIGH for 'pulse-width' microseconds, then LOW
* for 'pulse-width' microseconds.
* This pulsing creates a vibration of the desired frequency.
*
* (cleft) 2005 D. Cuartielles for K3
* Refactoring and comments 2006 clay.shirky@nyu.edu
* See NOTES in comments at end for possible improvements
*/
// TONES ==========================================
// Start by defining the relationship between
// note, period, & frequency.
#define c 3830 // 261 Hz
#define d 3400 // 294 Hz
#define e 3038 // 329 Hz
#define f 2864 // 349 Hz
#define g 2550 // 392 Hz
#define a 2272 // 440 Hz
#define b 2028 // 493 Hz
#define C 1912 // 523 Hz
// Define a special note, 'R', to represent a rest
#define R 0
// SETUP ============================================
// Set up speaker on a PWM pin (digital 9, 10 or 11)
int speakerOut = 9;
// Do we want debugging on serial out? 1 for yes, 0 for no
int DEBUG = 1;
void setup() {
pinMode(speakerOut, OUTPUT);
if (DEBUG) {
Serial.begin(9600); // Set serial out if we want debugging
}
}
// MELODY and TIMING =======================================
// melody[] is an array of notes, accompanied by beats[],
// which sets each note's relative length (higher #, longer note)
int melody[] = { C, b, g, C, b, e, R, C, c, g, a, C };
int beats[] = { 16, 16, 16, 8, 8, 16, 32, 16, 16, 16, 8, 8 };
int MAX_COUNT = sizeof(melody) / 2; // Melody length, for looping.
// Set overall tempo
long tempo = 10000;
// Set length of pause between notes
int pause = 1000;
// Loop variable to increase Rest length
int rest_count = 100; //<-BLETCHEROUS HACK; See NOTES
// Initialize core variables
int tone = 0;
int beat = 0;
long duration = 0;
// PLAY TONE ==============================================
// Pulse the speaker to play a tone for a particular duration
void playTone() {
long elapsed_time = 0;
if (tone > 0) { // if this isn't a Rest beat, while the tone has
// played less long than 'duration', pulse speaker HIGH and LOW
while (elapsed_time < duration) {
digitalWrite(speakerOut,HIGH);
delayMicroseconds(tone / 2);
// DOWN
digitalWrite(speakerOut, LOW);
delayMicroseconds(tone / 2);
// Keep track of how long we pulsed
elapsed_time += (tone);
}
}
else { // Rest beat; loop times delay
for (int j = 0; j < rest_count; j++) { // See NOTE on rest_count
delayMicroseconds(duration);
}
}
}
// LET THE WILD RUMPUS BEGIN =============================
void loop() {
// Set up a counter to pull from melody[] and beats[]
for (int i=0; i<MAX_COUNT; i++) {
tone = melody[i];
beat = beats[i];
duration = beat * tempo; // Set up timing
playTone();
// A pause between notes...
delayMicroseconds(pause);
if (DEBUG) { // If debugging, report loop, tone, beat, and duration
Serial.print(i);
Serial.print(":");
Serial.print(beat);
Serial.print(" ");
Serial.print(tone);
Serial.print(" ");
Serial.println(duration);
}
}
}
/*
* NOTES
* The program purports to hold a tone for 'duration' microseconds.
* Lies lies lies! It holds for at least 'duration' microseconds, _plus_
* any overhead created by incremeting elapsed_time (could be in excess of
* 3K microseconds) _plus_ overhead of looping and two digitalWrites()
*
* As a result, a tone of 'duration' plays much more slowly than a rest
* of 'duration.' rest_count creates a loop variable to bring 'rest' beats
* in line with 'tone' beats of the same length.
*
* rest_count will be affected by chip architecture and speed, as well as
* overhead from any program mods. Past behavior is no guarantee of future
* performance. Your mileage may vary. Light fuse and get away.
*
* This could use a number of enhancements:
* ADD code to let the programmer specify how many times the melody should
* loop before stopping
* ADD another octave
* MOVE tempo, pause, and rest_count to #define statements
* RE-WRITE to include volume, using analogWrite, as with the second program at
* http://www.arduino.cc/en/Tutorial/PlayMelody
* ADD code to make the tempo settable by pot or other input device
* ADD code to take tempo or volume settable by serial communication
* (Requires 0005 or higher.)
* ADD code to create a tone offset (higer or lower) through pot etc
* REPLACE random melody with opening bars to 'Smoke on the Water'
*/
