loading
It's fun! Don't give up! I won't.

Step 1: Build the Auduino!

This project is simple, and very fun. Kudos to Peter Knight!

People generally recommend prototyping with a breadboard to make sure your pots work, decide on a layout, etc.

Wire it up according to the instructions HERE:
https://code.google.com/p/tinkerit/wiki/Auduino

And then, update it with this to get it working with Arduino 1.0:

http://rcarduino.blogspot.com/2012/11/auduino-wit...


Step 2: Buttons!

RCArduino also includes instructions to add a switch to use delay. I prototyped with the breadboard and some gator clips a switch to pin 4. Don't forget to use a pull down resistor. It worked nice, so I decided to try and add some more buttons and some new effects.

If you are having trouble with switches, read this:

http://www.ladyada.net/learn/arduino/lesson5.html

Here is the code from RCarduino's blog:

/// 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)

#include
#include

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

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

// DB
#define SMOOTH_PIN 8


// 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
#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
#define PWM_VALUE OCR2B
#define LED_PIN 13
#define LED_PORT PORTB
#define LED_BIT 5
#define PWM_INTERRUPT TIMER2_OVF_vect
#endif

// Duane B
// rcarduino.blogspot.com
// 15/11/2012
// Very simple ring buffer delay
// we record the output in this array
// and then mix it back in with the output as the buffer wraps around
// can be switched on and off by a button on DELAY_BUTTON
#define MAX_DELAY 1024
unsigned char sDelayBuffer[MAX_DELAY];
unsigned int nDelayCounter = 0;
unsigned char bDelay;

#define DELAY_BUTTON 4


// 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[] = {
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
};
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]);
}


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(LED_PIN,OUTPUT);

pinMode(DELAY_BUTTON,INPUT);

// set pin mode and turn on pull up so that default mode
// is PENTATONIC, pull the pin low to switch to smooth
pinMode(SMOOTH_PIN,INPUT);
digitalWrite(SMOOTH_PIN,HIGH);
}

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.

// defaults to pentatonic stepped tones, pull pin low for smooth frequency without distinct tones
// syncPhaseInc = mapPhaseInc(analogRead(SYNC_CONTROL)) / 4;

syncPhaseInc = mapPentatonic(analogRead(SYNC_CONTROL));

// updated 29/01/2013
// pull the DELAY_BUTTON pin high for delay, low for no delay
// use either a pull up/pull down resistor
// or a pull up resistor with a toggle switch between the pin and ground
bDelay = digitalRead(DELAY_BUTTON);

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

// Stepped pentatonic mapping: D, E, G, A, B


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;
}


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;

// Duane B
// rcarduino.blogspot.com
// 15/11/2012
// add a button to set bDelay true or false to turn delay on and off
if(bDelay)
{
// Output to PWM (this is faster than using analogWrite)
// Here we add the delay buffer to the output value, this produces
// an subtle echo effect, the delay buffer is effectivley replaying the sound from
// 1/8th of a second ago.

LED_PORT |= 1 << LED_BIT; // Faster than using digitalWrite
PWM_VALUE = (output + (sDelayBuffer[nDelayCounter]))>>1;

// add the new output to the buffer so we can use it when the buffer next wraps around
sDelayBuffer[nDelayCounter] = PWM_VALUE;
nDelayCounter++;
if(nDelayCounter == MAX_DELAY)
{
nDelayCounter = 0;
}
}
else
{
LED_PORT &= ~(1 << LED_BIT); // Faster than using digitalWrite

PWM_VALUE = output;
}
}

Step 3: More Buttons!

What other effects can you add? I tried added a pause function and a dim function, by using bitwise operators to distort the PWM_OUTPUT using if statements at the bottom of the code. I was having trouble with the C++ language that Auduino library seems to be using and which operators I could get working, but managed to get these going.

The pause feature I added also has some background noise that I think is because of the delay feature. Couldn't get rid of it, but in short presses you don't notice, it is only if you press the pause button for more then a moment, and only occurs when the potentiometers are in extreme positions.


I used these buttons:

http://www.adafruit.com/products/1010

They are colorful, large, and fun to press. They solder into PCB pretty nice.

At this point I also soldered up the whole project to a proto shield to make it more sturdy and compact.

Here is the Peter Knight code from RCArduino's blog with the pause button and the "dim" button that I added that sort of distort-y lowers the volume when pressed. It makes a cool percussive element at some frequencies. The pause button is really fun to play with, too.

// 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)

#include
#include

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

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

// DB
#define SMOOTH_PIN 8


// 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
#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
#define PWM_VALUE OCR2B
#define LED_PIN 13
#define LED_PORT PORTB
#define LED_BIT 5
#define PWM_INTERRUPT TIMER2_OVF_vect
#endif

// Duane B
// rcarduino.blogspot.com
// 15/11/2012
// Very simple ring buffer delay
// we record the output in this array
// and then mix it back in with the output as the buffer wraps around
// can be switched on and off by a button on DELAY_BUTTON
#define MAX_DELAY 1024
unsigned char sDelayBuffer[MAX_DELAY];
unsigned int nDelayCounter = 0;
unsigned char bDelay;

#define DELAY_BUTTON 10


// following example fo delay effect, introducting unsigned variable and defingint he pinout for the puase effect
unsigned char bSync;
unsigned char bPause;

#define PAUSE_BUTTON 12
#define SYNC_BUTTON 11


//4,5,10



// 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[] = {
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
};
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]);
}


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(LED_PIN,OUTPUT);

pinMode(DELAY_BUTTON,INPUT);

//setting my buttons as inputs, following example of the delay effect

pinMode(SYNC_BUTTON, INPUT);
pinMode(PAUSE_BUTTON, INPUT);

// set pin mode and turn on pull up so that default mode
// is PENTATONIC, pull the pin low to switch to smooth
pinMode(SMOOTH_PIN,INPUT);
digitalWrite(SMOOTH_PIN,HIGH);
}

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.

// defaults to pentatonic stepped tones, pull pin low for smooth frequency without distinct tones
syncPhaseInc = mapPhaseInc(analogRead(SYNC_CONTROL)) / 4;

//syncPhaseInc = mapPentatonic(analogRead(SYNC_CONTROL));

// updated 29/01/2013
// pull the DELAY_BUTTON pin high for delay, low for no delay
// use either a pull up/pull down resistor
// or a pull up resistor with a toggle switch between the pin and ground
bDelay = digitalRead(DELAY_BUTTON);
bSync = digitalRead(SYNC_BUTTON);
bPause = digitalRead(PAUSE_BUTTON);

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

// Stepped pentatonic mapping: D, E, G, A, B


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;
}


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;

// Duane B
// rcarduino.blogspot.com
// 15/11/2012
// add a button to set bDelay true or false to turn delay on and off

if(bDelay)
{
// Output to PWM (this is faster than using analogWrite)
// Here we add the delay buffer to the output value, this produces
// an subtle echo effect, the delay buffer is effectivley replaying the sound from
// 1/8th of a second ago.

LED_PORT |= 1 << LED_BIT; // Faster than using digitalWrite
PWM_VALUE = (output + (sDelayBuffer[nDelayCounter]))>>1;

// add the new output to the buffer so we can use it when the buffer next wraps around
sDelayBuffer[nDelayCounter] = PWM_VALUE;
nDelayCounter++;
if(nDelayCounter == MAX_DELAY)
{
nDelayCounter = 0;
}
}
else
{
LED_PORT &= ~(1 << LED_BIT); // Faster than using digitalWrite

PWM_VALUE = output;
}


//kyle
//taking the example from above and trying to add a percussive pause and dim feature to button 11 and 12
//it works and but is hard to get the delay and the pause to work together, sometimes when it is paused, there is background noise now

if (bSync)
{
//by leaving this blank, the delay effect is allowed to work, instead of being overwritten by what i had here

}
else
{
// ++ makes a dimming effect
LED_PORT |= 1 << LED_BIT; // Faster than using digitalWrite
PWM_VALUE = (output ++ )>>1;

}

//added another effect which slightly dims the sound

if (bPause)
{
}
else
{
// shifting the bits off the scale to get a "pause" button worked well!
LED_PORT |= 1 << LED_BIT; // Faster than using digitalWrite
PWM_VALUE = (output <<50 )>>1;

}
}


Step 4: Play!

Mess with the code, try different sensors in place of potentiometers, and then solder it up to a compact package and take it on the go! Impress your friends, and your mom.

What other button features can you get going? I think some sort of jagged blip would be cool.





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