Arduino Audio Input

Send sound into your Arduino. This Instructable will show you how to prepare audio so that it can be sampled and processed by an Arduino to make sound responsive projects and audio effects. (This article is a companion to another Instructable I've written about building an audio output circuit for an Arduino, find that here)

Some ideas that come to mind include:

beat detection- trigger lighting effects, build a set of turntables that beat match themselves, or make a robot that dances along with the music you play for it
amplitude detection- make a simple vu meter with LEDS
frequency analysis- you could make a project that reacts to different frequencies in different ways, recognizes certain melodies, turns audio into MIDI data, or translates incoming frequencies into square waves with the tone() library
digital effects boxes/digital signal processing- check out what I did with my vocal effects box (all processing done with Arduino), lots of possibilities here: pitch bending, distortion, sampling, delay, reverb, granular synthesis, mixing, and much more... I've provided code in this Instructable that lets you sample at up to 38.5kHz. Here is another instructable describing how to set up a simple audio out circuit with Arduino.
digital recorder- with the addition of an SD card of course (the Arduino has very limited memory by itself), this opens up the possibility of looping large samples and doing lots of other digital manipulations to pieces of stored audio The circuits and code provided here are compatible with SD card shields that communicate via SPI.
graphical representations of sound- Arduino oscilloscope/visualizer

Feel free to use any of the info in this Instructable to put together an amazing project for the DIY Audio Contest! We're giving away an HDTV, some DSLR cameras, and tons of other great stuff! The contest closes Nov 26.

Parts list:
(x1) Microphone Radioshack 33-3038
(x1) TL072 Digikey 296-14997-5-ND or TL082 Digikey 296-1780-5-ND (TL081/TL071 are fine too) I used a tl082 in my examples
(x2) 9V battery
(x2) 9V battery snap connector Radioshack 270-324
(x1) mono audio jack 1/4" Radioshack 274-340 or Radioshack 274-252 or 1/8" Radioshack 274-333 or Radioshack 274-251
(x1) LED Digikey C513A-WSN-CV0Y0151-ND
(x1) 10kOhm potentiometer linear Digikey 987-1301-ND
(x3) 100kOhm 1/4watt resistors Digikey CF14JT100KCT-ND
(x1) 10uF electrolytic capacitor Digikey P5134-ND
(x1) 47nF ceramic capacitor Digikey P4307-ND
(x1) Arduino Uno (Duemilanove is fine too) Amazon

Additional Materials:

(1x) usb cable Amazon
(1x) breadboard (this one comes with jumper wires) Amazon
(1x) jumper wires Amazon

//Simple Audio In
//by Amanda Ghassaei
//https://www.instructables.com/id/Arduino-Audio-Input/
//Sept 2012

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
*/

int incomingAudio;

void setup(){
}

void loop(){
  incomingAudio = analogRead(A0);//read input from A0
  //do stuff with the variable "incomingAudio"
}

//Simple Audio In w output to 8 bit DAC
//by Amanda Ghassaei
//https://www.instructables.com/id/Arduino-Audio-Input/
//Sept 2012

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
*/

int incomingAudio;

void setup(){
  for (byte i=0;i<8;i++){
    pinMode(i,OUTPUT);//set digital pins 0-7 as outputs (DAC)
  }
}

void loop(){
  incomingAudio = analogRead(A0);//read voltage at A0
  incomingAudio = (incomingAudio+1)/4 - 1;//scale from 10 bit (0-1023) to 8 bit (0-255)
  if (incomingAudio<0){//deal with negative numbers
    incomingAudio = 0;
  }
  PORTD = incomingAudio;
}

//Audio out with 38.5kHz sampling rate
//by Amanda Ghassaei
//https://www.instructables.com/id/Arduino-Audio-Input/
//Sept 2012

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
*/

int incomingAudio;//storage for A0 data

void setup(){
  
  //set up continuous sampling of analog pin 0 (you don't need to understand this part, just know how to use it in the loop())
  
  //clear ADCSRA and ADCSRB registers
  ADCSRA = 0;
  ADCSRB = 0;
  
  ADMUX |= (1 << REFS0); //set reference voltage
  ADMUX |= (1 << ADLAR); //left align the ADC value- so we can read highest 8 bits from ADCH register only
  
  ADCSRA |= (1 << ADPS2) | (1 << ADPS0); //set ADC clock with 32 prescaler- 16mHz/32=500kHz
  ADCSRA |= (1 << ADATE); //enabble auto trigger
  ADCSRA |= (1 << ADEN); //enable ADC
  ADCSRA |= (1 << ADSC); //start ADC measurements
  
  //if you want to add other things to setup(), do it here

}

void loop(){
  incomingAudio = ADCH;//get new value from A0
  //do other stuff here
}

//Audio out with 38.5kHz sampling rate and DAC output
//by Amanda Ghassaei
//https://www.instructables.com/id/Arduino-Audio-Input/
//Sept 2012

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
*/

void setup(){

  for (byte i=0;i<8;i++){
    pinMode(i,OUTPUT);
  }
  
  //set up continuous sampling of analog pin 0
  
  //clear ADCSRA and ADCSRB registers
  ADCSRA = 0;
  ADCSRB = 0;
  
  ADMUX |= (1 << REFS0); //set reference voltage
  ADMUX |= (1 << ADLAR); //left align the ADC value- so we can read highest 8 bits from ADCH register only
  
  ADCSRA |= (1 << ADPS2) | (1 << ADPS0); //set ADC clock with 32 prescaler- 16mHz/32=500kHz
  ADCSRA |= (1 << ADATE); //enabble auto trigger
  ADCSRA |= (1 << ADEN); //enable ADC
  ADCSRA |= (1 << ADSC); //start ADC measurements
  
  //if you want to add other things to setup(), do it here

}

void loop(){
  PORTD = ADCH;//send 8 bit value from analog pin 0 to DAC
}

//Audio out with 38.5kHz sampling rate and interrupts
//by Amanda Ghassaei
//https://www.instructables.com/id/Arduino-Audio-Input/
//Sept 2012

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
*/

int incomingAudio;

void setup(){

  cli();//disable interrupts
  
  //set up continuous sampling of analog pin 0
  
  //clear ADCSRA and ADCSRB registers
  ADCSRA = 0;
  ADCSRB = 0;
  
  ADMUX |= (1 << REFS0); //set reference voltage
  ADMUX |= (1 << ADLAR); //left align the ADC value- so we can read highest 8 bits from ADCH register only
  
  ADCSRA |= (1 << ADPS2) | (1 << ADPS0); //set ADC clock with 32 prescaler- 16mHz/32=500kHz
  ADCSRA |= (1 << ADATE); //enabble auto trigger
  ADCSRA |= (1 << ADIE); //enable interrupts when measurement complete
  ADCSRA |= (1 << ADEN); //enable ADC
  ADCSRA |= (1 << ADSC); //start ADC measurements
  
  sei();//enable interrupts

  //if you want to add other things to setup(), do it here

}

ISR(ADC_vect) {//when new ADC value ready
  incomingAudio = ADCH;//update the variable incomingAudio with new value from A0 (between 0 and 255)
}

void loop(){
//do other stuff here
}

//Simple Audio In with clipping indicator
//by Amanda Ghassaei
//https://www.instructables.com/id/Arduino-Audio-Input/
//Sept 2012

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
*/

int incomingAudio;
boolean clipping = 0;//zero = not clipping, one = currently clipping
int clippingCounter = 5000;

void setup(){
}

void loop(){
  incomingAudio = analogRead(A0);//read input from A0
  //do stuff with the variable "incomingAudio"
  if (incomingAudio == 0 || incomingAudio == 1023){//if clipping
    digitalWrite(13,HIGH);//set pin 13 high
    clipping = 1;//currently clipping
    clippingCounter = 5000;//reset clippingCounter
  }
  if (clipping){
    if (clippingCounter>0){
      clippingCounter--;//decrement clipping counter
    }
    else{//if clippingCounter has counted all the way down
      clipping = 0;//no longer clipping
      digitalWrite(13,LOW);//turn of clipping indicator
    }
  }
}

//Audio in with 38.5kHz sampling rate, interrupts, and clipping indicator
//by Amanda Ghassaei
//https://www.instructables.com/id/Arduino-Audio-Input/
//Sept 2012

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
*/

//variable to store incoming audio sample
byte incomingAudio;

//clipping indicator variables
boolean clipping = 0;

void setup(){
  
  pinMode(13,OUTPUT);//led indicator pin
  
  cli();//disable interrupts
  
  //set up continuous sampling of analog pin 0
  
  //clear ADCSRA and ADCSRB registers
  ADCSRA = 0;
  ADCSRB = 0;
  
  ADMUX |= (1 << REFS0); //set reference voltage
  ADMUX |= (1 << ADLAR); //left align the ADC value- so we can read highest 8 bits from ADCH register only
  
  ADCSRA |= (1 << ADPS2) | (1 << ADPS0); //set ADC clock with 32 prescaler- 16mHz/32=500kHz
  ADCSRA |= (1 << ADATE); //enabble auto trigger
  ADCSRA |= (1 << ADIE); //enable interrupts when measurement complete
  ADCSRA |= (1 << ADEN); //enable ADC
  ADCSRA |= (1 << ADSC); //start ADC measurements
  
  sei();//enable interrupts

  //if you want to add other things to setup(), do it here

}

ISR(ADC_vect) {//when new ADC value ready
  incomingAudio = ADCH;//store 8 bit value from analog pin 0
  if (incomingAudio == 0 || incomingAudio == 255){//if clipping
    digitalWrite(13,HIGH);//set pin 13 high
    clipping = 1;//currently clipping
  }
}

void loop(){
  if (clipping){//if currently clipping
    clipping = 0;//
    digitalWrite(13,LOW);//turn off clipping led indicator (pin 13)
  }

  delay(100);
}