We have a small pressure pad that acts as a volume pedal, and we can select predefined tones from the knob (potentiometer). The tones were defined as the one octave scale in the natural key of C (see code below). The potentiometer sensor produces an analog input to our Arduino board, and the Arduino board was programmed to produce a digital output corresponding to the frequency of the note. The volume pedal is in series with the speaker.
We noticed the pedal was a create user-interface. It provided smooth, continuous feedback and was very easy to operate. Although we didn't get around to it, it could make a good controller for pitch due to it's continuous response to force (although sustaining extreme notes requiring high force input may be uncomfortable).
Here's a schematic of our instrument:
Here's the code we programmed into the Arduino, based on Arduino's Melody example:
/* Melody
* (cleft) 2005 D. Cuartielles for K3
* Modified by Andrew Rohr, Anish Joshi, Michael Woon
*
* This example uses a piezo speaker to play melodies. It sends
* a square wave of the appropriate frequency to the piezo, generating
* the corresponding tone.
*
* The calculation of the tones is made following the mathematical
* operation:
*
* timeHigh = period / 2 = 1 / (2 * toneFrequency)
*
* where the different tones are described as in the table:
*
* note frequency period timeHigh
* c 261 Hz 3830 1915
* d 294 Hz 3400 1700
* e 329 Hz 3038 1519
* f 349 Hz 2864 1432
* g 392 Hz 2550 1275
* a 440 Hz 2272 1136
* b 493 Hz 2028 1014
* C 523 Hz 1912 956
*
* http://www.arduino.cc/en/Tutorial/Melody
*/
#include
int tone=0;
int addr = 0;
int speakerPin = 9;
int ledPin = 13;
int sensorPin = 0; //Analog Input ~0-5V
float sensorValue = 0;
char n = 'c';
char n1='c';
int length = 15; // the number of notes
float prevval=0;
float val=0;
int j=2;
void setup() {
pinMode(speakerPin, OUTPUT);
pinMode(ledPin, OUTPUT);
pinMode(sensorPin, INPUT);
}
void loop() {
sensorValue = analogRead(sensorPin)/100;
if(prevval!=sensorValue)
{
EEPROM.write(addr,sensorValue);
addr=addr+1;
}
if(addr == 512)
addr=0;
if (sensorValue <= 1){ n1 = 'c'; digitalWrite(ledPin,HIGH); //playNote(n); } if (sensorValue > 1 && sensorValue <= 2){ digitalWrite(ledPin,LOW); n1 = 'd'; //playNote(n); } if (sensorValue > 2 && sensorValue <= 3){ n1 = 'e'; digitalWrite(ledPin,HIGH); //playNote(n); } if (sensorValue > 3 && sensorValue <= 4){ n1 = 'f'; digitalWrite(ledPin,LOW); //playNote(n); } if (sensorValue > 4 && sensorValue <= 5){ n1 = 'g'; digitalWrite(ledPin,HIGH); // playNote(n); } if (sensorValue > 5 && sensorValue <= 6){ n1 = 'a'; digitalWrite(ledPin,LOW); // playNote(n); } if (sensorValue > 6 && sensorValue <= 7){ n1 = 'b'; digitalWrite(ledPin,HIGH); //playNote(n); } if (sensorValue > 7 && sensorValue <= 8){ n1 = 'C'; digitalWrite(ledPin,LOW); //playNote(n); } char names[] = { 'c', 'd', 'e', 'f', 'g', 'a', 'b', 'C' }; int tones[] = { 1915, 1700, 1519, 1432, 1275, 1136, 1014, 956 }; n=n1; // play the tone corresponding to the note name for (int i = 0; i < tone="tones[i];" j="2;">0)
{
int sensor = 0;
sensor=analogRead(sensorPin);
if(sensorValue!=sensor)
j=-1;
digitalWrite(speakerPin, HIGH);
delayMicroseconds(tone);
digitalWrite(speakerPin, LOW);
delayMicroseconds(tone);
}
}
}
n1 ='d';
prevval=sensorValue;
}
n1 ='d';
prevval=sensorValue;
}
