Synthesizer

 

I made a a granular synthesizer. I combined a few tutorials I found online for different granular synths using code called “auduino” by peter knight.

http://www.instructables.com/id/The-Arduino-Synthesizer/

http://www.instructables.com/id/How-to-build-an-Arduino-synth/

https://code.google.com/p/tinkerit/wiki/Auduino

 

the synth has pots for pitch 1 and 2 and pots for decay 1 and decay 2. the 5th pot is  for repetition frequency. with the click of a button, the synth can use a pressure sensor in place of pot 5 to control the repetition frequency.

there is also a button that cycles through 6 different modes. basically changing the scale (or sometimes no scale) that is heard when the repetition frequency changes.

 

here is the code I used-

// Auduino, the Lo-Fi granular synthesiser
//
// by Peter Knight, Tinker.it http://tinker.it
//
// Help: http://code.google.com/p/tinkerit/wiki/Auduino
// More help: http://groups.google.com/group/auduino
//
// Analog in 0: Grain 1 pitch
// Analog in 1: Grain 2 decay
// Analog in 2: Grain 1 decay
// Analog in 3: Grain 2 pitch
// Analog in 4: Grain repetition frequency
//
// Digital 3: Audio out (Digital 11 on ATmega8)
//
// Changelog:
// 19 Nov 2008: Added support for ATmega8 boards
// 21 Mar 2009: Added support for ATmega328 boards
// 7 Apr 2009: Fixed interrupt vector for ATmega328 boards
// 8 Apr 2009: Added support for ATmega1280 boards (Arduino Mega)
// 11 Mar 2012: edit code to fit corresponding Fritzing diagram.

/*
10/07/10 Prodical contributed:
– additional mapping modes – diatonic major and minor and pentatonic major and minor
– switchable between modes by a single button which cycles through each and differentiates by an LED blinking as per the mode number
– a light dependent resistor (LDR) – calibrated in the first five seconds after switching on – replacing the main (grain repetition) frequency pot on a switch (using an external interrupt) with an LED indicator when it’s active but which also dims according on the LDR value
more details at http://blog.lewissykes.info
*/

/*
Calibration

Demonstrates one techinque for calibrating sensor input. The
sensor readings during the first five seconds of the sketch
execution define the minimum and maximum of expected values
attached to the sensor pin.

The sensor minumum and maximum initial values may seem backwards.
Initially, you set the minimum high and listen for anything
lower, saving it as the new minumum. Likewise, you set the
maximum low and listen for anything higher as the new maximum.

The circuit:
* Analog sensor (potentiometer will do) attached to analog input 0
* LED attached from digital pin 9 to ground

created 29 Oct 2008
By David A Mellis
Modified 17 Jun 2009
By Tom Igoe

http://arduino.cc/en/Tutorial/Calibration

This example code is in the public domain.

*/

// AUDUINO code STARTS
#include <avr/io.h>
#include <avr/interrupt.h>

uint16_t syncPhaseAcc;
uint16_t syncPhaseInc;
uint16_t grainPhaseAcc;
uint16_t grainPhaseInc;
uint16_t grainAmp;
uint8_t grainDecay;
uint16_t grain2PhaseAcc;
uint16_t grain2PhaseInc;
uint16_t grain2Amp;
uint8_t grain2Decay;

// Map Analogue channels
#define SYNC_CONTROL (4)
#define GRAIN_FREQ_CONTROL (3)
#define GRAIN_DECAY_CONTROL (2)
#define GRAIN2_FREQ_CONTROL (1)
#define GRAIN2_DECAY_CONTROL (0)

// Changing these will also requires rewriting audioOn()
#if defined(__AVR_ATmega8__)
//
// On old ATmega8 boards.
// Output is on pin 11
//
#define LED_PIN 13
#define LED_PORT PORTB
#define LED_BIT 5
#define PWM_PIN 11
#define PWM_VALUE OCR2
#define PWM_INTERRUPT TIMER2_OVF_vect
#elif defined(__AVR_ATmega1280__)
//
// On the Arduino Mega
// Output is on pin 3
//
#define LED_PIN 13
#define LED_PORT PORTB
#define LED_BIT 7
#define PWM_PIN 3 //3
#define PWM_VALUE OCR3C
#define PWM_INTERRUPT TIMER3_OVF_vect
#else
//
// For modern ATmega168 and ATmega328 boards
// Output is on pin 3
//
#define PWM_PIN 3 //3
#define PWM_VALUE OCR2B
#define LED_PIN 13
#define LED_PORT PORTB
#define LED_BIT 5
#define PWM_INTERRUPT TIMER2_OVF_vect
#endif
// AUDUINO code ENDS
// BUTTON, SWITCH, LDR & LEDs – START
// Button
#define BUTTON_PIN (6) // the number of the pushbutton pin
int buttonValue; // variable for reading the button status
int buttonState; // variable to hold the button state
int mapMode = 0; // What scale/mapping mode is in use?

// LDR
//#define LDRSWITCH (4)
// switch replaced by external interrupt
volatile int LDRswitchState = LOW;
#define LDR_PIN (5)
#define LDRLED_PIN (9)
//Callibration variables
int LDRValue = 0; // the sensor value
int LDRMin = 1023; // minimum sensor value
int LDRMax = 0; // maximum sensor value

// PWM_VALUE LED
#define FRQLED_PIN (11) // not as consistent as pin 13

// mapmode LED
#define mapModeLED_PIN (10) // the number of the LED pin
int mapModeLEDState = LOW; // ledState used to set the LED
long previousMillis = 0; // will store last time LED was updated
int BlinkRate = 5; // no of blinks per second i.e. fps – empirically tested as just slow enough to count
int BlinkCount = 0; // variable to store no of blinks
int BlinkLoopLength = 14; // err… blink loop length

// BUTTON, SWITCH, LDR & LEDs – ENDS
// MAPPINGS – START
// Smooth logarithmic mapping
//
uint16_t antilogTable[] = {
64830,64132,63441,62757,62081,61413,60751,60097,59449,58809,58176,57549,56929,56316,55709,55109,
54515,53928,53347,52773,52204,51642,51085,50535,49991,49452,48920,48393,47871,47356,46846,46341,
45842,45348,44859,44376,43898,43425,42958,42495,42037,41584,41136,40693,40255,39821,39392,38968,
38548,38133,37722,37316,36914,36516,36123,35734,35349,34968,34591,34219,33850,33486,33125,32768
};
uint16_t mapPhaseInc(uint16_t input) {
return (antilogTable[input & 0x3f]) >> (input >> 6);
}

// Stepped chromatic mapping
//
uint16_t midiTable[] = {
0,17,18,19,20,22,23,24,26,27,29,31,32,34,36,38,41,43,46,48,51,54,58,61,65,69,73,
77,82,86,92,97,103,109,115,122,129,137,145,154,163,173,183,194,206,218,231,
244,259,274,291,308,326,346,366,388,411,435,461,489,518,549,581,616,652,691,
732,776,822,871,923,978,1036,1097,1163,1232,1305,1383,1465,1552,1644,1742,
1845,1955,2071,2195,2325,2463,2610,2765,2930,3104,3288,3484,3691,3910,4143,
4389,4650,4927,5220,5530,5859,6207,6577,6968,7382,7821,8286,8779,9301,9854,
10440,11060,11718,12415,13153,13935,14764,15642,16572,17557,18601,19708,20879,
22121,23436,24830,26306,27871
};
uint16_t mapMidi(uint16_t input) {
return (midiTable[(1023-input) >> 3]);
}

//// Stepped Pentatonic mapping
//
uint16_t pentatonicTable[54] = {
0,19,22,26,29,32,38,43,51,58,65,77,86,103,115,129,154,173,206,231,259,308,346,
411,461,518,616,691,822,923,1036,1232,1383,1644,1845,2071,2463,2765,3288,
3691,4143,4927,5530,6577,7382,8286,9854,11060,13153,14764,16572,19708,22121,26306
};

uint16_t mapPentatonic(uint16_t input) {
uint8_t value = (1023-input) / (1024/53);
return (pentatonicTable[value]);
}

// Lewis added – I’ve got an Excel spreadsheet with these workings out on my blog…
// Stepped major Diatonic mapping
//
uint16_t majordiatonicTable[76] = {
0,17,19,22,23,26,29,32,34,38,43,46,51,58,65,69,77,86,92,103,115,129,137,154,173,183,206,231,259,274,308,346,366,
411,461,518,549,616,691,732,822,923,1036,1097,1232,1383,1465,1644,1845,2071,2195,2463,2765,2930,3288,
3691,4143,4389,4927,5530,5859,6577,7382,8286,8779,9854,11060,11718,13153,14764,16572,17557,19708,22121,23436,26306
};

uint16_t mapmajorDiatonic(uint16_t input) {
uint8_t value = (1023-input) / (1024/53);
return (majordiatonicTable[value]);
}

// Stepped minor Diatonic mapping
//
uint16_t minordiatonicTable[76] = {
0,17,19,20,23,26,27,31,34,38,41,46,51,54,61,69,77,82,92,103,109,122,137,154,163,183,206,218,244,274,308,326,366,
411,435,489,549,616,652,732,822,871,978,1097,1232,1305,1465,1644,1742,1955,2195,2463,2610,2930,3288,
3484,3910,4389,4927,5220,5859,6577,6968,7821,8779,9854,10440,11718,13153,13935,15642,17557,19708,20879,23436,26306
};

uint16_t mapminorDiatonic(uint16_t input) {
uint8_t value = (1023-input) / (1024/53);
return (minordiatonicTable[value]);
}

// Stepped major Pentatonic mapping
//
uint16_t majorpentatonicTable[55] = {
0,17,19,22,26,29,34,38,43,51,58,69,77,86,103,115,137,154,173,206,231,274,308,346,
411,461,549,616,691,822,923,1097,1232,1383,1644,1845,2195,2463,2765,3288,
3691,4389,4927,5530,6577,7382,8779,9854,11060,13153,14764,17557,19708,22121,26306
};

uint16_t mapmajorPentatonic(uint16_t input) {
uint8_t value = (1023-input) / (1024/53);
return (majorpentatonicTable[value]);
}

// Stepped minor Pentatonic mapping
//
uint16_t minorpentatonicTable[55] = {
0,17,20,23,26,31,34,41,46,51,61,69,82,92,103,122,137,163,183,206,244,274,326,366,
411,489,549,652,732,822,978,1097,1305,1465,1644,1955,2195,2610,2930,3288,
3910,4389,5220,5859,6577,7821,8779,10440,11718,13153,15642,17557,20879,23436,26306
};

uint16_t mapminorPentatonic(uint16_t input) {
uint8_t value = (1023-input) / (1024/53);
return (pentatonicTable[value]);
}
// MAPPINGS – END
void audioOn() {
#if defined(__AVR_ATmega8__)
// ATmega8 has different registers
TCCR2 = _BV(WGM20) | _BV(COM21) | _BV(CS20);
TIMSK = _BV(TOIE2);
#elif defined(__AVR_ATmega1280__)
TCCR3A = _BV(COM3C1) | _BV(WGM30);
TCCR3B = _BV(CS30);
TIMSK3 = _BV(TOIE3);
#else
// Set up PWM to 31.25kHz, phase accurate
TCCR2A = _BV(COM2B1) | _BV(WGM20);
TCCR2B = _BV(CS20);
TIMSK2 = _BV(TOIE2);
#endif
}
void setup() {

pinMode(PWM_PIN,OUTPUT);
audioOn();
pinMode(LDRLED_PIN,OUTPUT);
pinMode(FRQLED_PIN,OUTPUT);
pinMode(mapModeLED_PIN,OUTPUT);
pinMode(BUTTON_PIN,INPUT);
attachInterrupt(0, LDRswitched, CHANGE);
}

// // Calibration
//Serial.begin(9600);
// turn on LED to signal the start of the calibration period:
// pinMode(9, OUTPUT);
// digitalWrite(9, HIGH);
// // calibrate during the first five seconds
// while (millis() < 5000) {
// LDRValue = analogRead(LDR_PIN);
// // record the maximum sensor value
// if (LDRValue > LDRMax) {
// LDRMax = LDRValue;
// }
// // record the minimum sensor value
// if (LDRValue < LDRMin) {
// LDRMin = LDRValue;
// }
// }
// // signal the end of the calibration period
// digitalWrite(9, LOW);
//// // END calibration code
////
////}
void LDRswitched(){
LDRswitchState = !LDRswitchState;
}
void loop() {
// The loop is pretty simple – it just updates the parameters for the oscillators.
//
// Avoid using any functions that make extensive use of interrupts, or turn interrupts off.
// They will cause clicks and poops in the audio.

// Smooth frequency mapping
//syncPhaseInc = mapPhaseInc(analogRead(SYNC_CONTROL)) / 4;

// Stepped mapping to MIDI notes: C, Db, D, Eb, E, F…
//syncPhaseInc = mapMidi(analogRead(SYNC_CONTROL));

// // Stepped pentatonic mapping: D, E, G, A, B
// syncPhaseInc = mapPentatonic(analogRead(SYNC_CONTROL));

// could add switch here to choose between midiIn() and the twisty-pot pitch control

//BEGIN Calibration
// read the sensor:
LDRValue = analogRead(LDR_PIN);
// apply the calibration to the sensor reading
LDRValue = map(LDRValue, LDRMin, LDRMax, 0, 1023);
// in case the sensor value is outside the range seen during calibration
LDRValue = constrain(LDRValue, 0, 1023);
// // fade the LED using the calibrated value: (this moved below)
// analogWrite(LDRLED_PIN, LDRValue);
// Serial.println(LDRValue);
//END Calibration
LDRValue=analogRead(LDR_PIN);
//
if (LDRValue==HIGH){
LDRswitched(); }
//

// button presses cycle through scales/mapping modes
buttonValue = digitalRead(BUTTON_PIN); // read input value and store it in val
if (buttonValue != buttonState) { // the button state has changed!
if (buttonValue == 0) { // check if the button is pressed
if (mapMode == 0) { // if set to smooth logarithmic mapping
mapMode = 1; // switch to stepped chromatic mapping
}
else {
if (mapMode == 1) { // if stepped chromatic mapping
mapMode = 2; // switch to stepped major Diatonic mapping
}
else {
if (mapMode == 2) { // if stepped major Diatonic mapping
mapMode = 3; // switch to stepped minor Diatonic mapping
}
else {
if (mapMode == 3) { // if stepped minor Diatonic mapping
mapMode = 4; // switch to stepped major Pentatonic mapping
}
else {
if (mapMode == 4) { // if stepped major Pentatonic mapping
mapMode = 5; // switch to stepped minor Pentatonic mapping
}
else {
if (mapMode == 5) { // if stepped major Pentatonic mapping
mapMode = 0; // switch back to smooth logarithmic mapping
}
}
}
}
}
}
}
buttonState = buttonValue; // save the new state in our variable
}

// mapMode LED indicator – blinks number of scale/mapping mode on a fixed ‘frame’ cycle
if (millis() – previousMillis > 1000/BlinkRate)
{
BlinkCount = BlinkCount + 1;
// save the last time you blinked the LED
previousMillis = millis();
digitalWrite(mapModeLED_PIN, LOW);
if (BlinkCount <= (mapMode+1)*2)
{
//if the LED is off turn it on and vice-versa:
if (mapModeLEDState == LOW)
{
mapModeLEDState = HIGH;
}
else{
mapModeLEDState = LOW;
}
// set the LED with the ledState of the variable:
digitalWrite(mapModeLED_PIN, mapModeLEDState);
}
// resets Blink loop after 14 blinks
else if (BlinkCount >= BlinkLoopLength)
{
BlinkCount = 0;
}
//debug
//Serial.println(BlinkCount);
}

//Map modes to select with button. LED blinks as per mode currently in use
//selects which array to pull data from to get SyncPhaseInc
//1. Smooth logarithmic mapping
if (mapMode == 0) {
if (LDRswitchState == HIGH) {
syncPhaseInc = mapPhaseInc(LDRValue) / 4;
analogWrite(LDRLED_PIN, LDRValue);
}
else
{
syncPhaseInc = mapPhaseInc(analogRead(SYNC_CONTROL)) / 4;
digitalWrite(LDRLED_PIN, LOW);
}
}
//2. Stepped chromatic mapping to MIDI notes: C,C#,D,Eb,F,F#,G,Ab,A,Bb,B
if (mapMode == 1) {
if (LDRswitchState == HIGH) {
syncPhaseInc = mapMidi(1023-LDRValue);
analogWrite(LDRLED_PIN, LDRValue);
}
else
{
syncPhaseInc = mapMidi(analogRead(SYNC_CONTROL));
digitalWrite(LDRLED_PIN, LOW);
}
}
//3. Stepped major Diatonic mapping: C,D,E,F,G,A,B
if (mapMode == 2) {
if (LDRswitchState == HIGH) {
syncPhaseInc = mapmajorDiatonic(LDRValue);
analogWrite(LDRLED_PIN, LDRValue);
}
else
{
syncPhaseInc = mapmajorDiatonic(analogRead(SYNC_CONTROL));
digitalWrite(LDRLED_PIN, LOW);
}
}
//4. Stepped minor Diatonic mapping: C,D,Eb,F,G,Ab,Bb
if (mapMode == 3) {
if (LDRswitchState == HIGH) {
syncPhaseInc = mapminorDiatonic(LDRValue);
analogWrite(LDRLED_PIN, LDRValue);
}
else
{
syncPhaseInc = mapminorDiatonic(analogRead(SYNC_CONTROL));
digitalWrite(LDRLED_PIN, LOW);
}
}
//5. Stepped major Pentatonic mapping
if (mapMode == 4) {
if (LDRswitchState == HIGH) {
syncPhaseInc = mapmajorPentatonic(LDRValue);
analogWrite(LDRLED_PIN, LDRValue);
}
else
{
syncPhaseInc = mapmajorPentatonic(analogRead(SYNC_CONTROL));
digitalWrite(LDRLED_PIN, LOW);
}
}
//6. Stepped major Diatonic mapping
if (mapMode == 5) {
if (LDRswitchState == HIGH) {
syncPhaseInc = mapminorPentatonic(LDRValue);
analogWrite(LDRLED_PIN, LDRValue);
}
else
{
syncPhaseInc = mapminorPentatonic(analogRead(SYNC_CONTROL));
digitalWrite(LDRLED_PIN, LOW);
}
}

//input from pots
grainPhaseInc = mapPhaseInc(analogRead(GRAIN_FREQ_CONTROL)) / 2;
grainDecay = analogRead(GRAIN_DECAY_CONTROL) / 8;
grain2PhaseInc = mapPhaseInc(analogRead(GRAIN2_FREQ_CONTROL)) / 2;
grain2Decay = analogRead(GRAIN2_DECAY_CONTROL) / 4;

digitalWrite(FRQLED_PIN, PWM_VALUE);

}
SIGNAL(PWM_INTERRUPT)
{
uint8_t value;
uint16_t output;

syncPhaseAcc += syncPhaseInc;
if (syncPhaseAcc < syncPhaseInc) {
// Time to start the next grain
grainPhaseAcc = 0;
grainAmp = 0x7fff;
grain2PhaseAcc = 0;
grain2Amp = 0x7fff;
LED_PORT ^= 1 << LED_BIT; // Faster than using digitalWrite
}

// Increment the phase of the grain oscillators
grainPhaseAcc += grainPhaseInc;
grain2PhaseAcc += grain2PhaseInc;

// Convert phase into a triangle wave
value = (grainPhaseAcc >> 7) & 0xff;
if (grainPhaseAcc & 0x8000) value = ~value;
// Multiply by current grain amplitude to get sample
output = value * (grainAmp >> 8);

// Repeat for second grain
value = (grain2PhaseAcc >> 7) & 0xff;
if (grain2PhaseAcc & 0x8000) value = ~value;
output += value * (grain2Amp >> 8);

// Make the grain amplitudes decay by a factor every sample (exponential decay)
grainAmp -= (grainAmp >> 8) * grainDecay;
grain2Amp -= (grain2Amp >> 8) * grain2Decay;

// Scale output to the available range, clipping if necessary
output >>= 9;
if (output > 255) output = 255;

// Output to PWM (this is faster than using analogWrite)
PWM_VALUE = output;
}

 

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