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Acid Rain

Using my lofi delay object that creates 6 delay lines (octave up, octave down, no octave change plus each of those in reverse) and the glitch delay technique of crossfading between delay lines to jump about in time. This has to be the craziest effect I've ever made!


I've added a sample rate reducer and low pass filter at the end for extra garbled glitchiness. It's currently in Mono.


You need to create the lofi delay library for this sketch to run. Follow the instructions here LINK


A0 = Size (time between potential glitches)

A1 = Lowpass filter

A2 = Density (probability of glitching

A3 = Sample rate

Toggle = Different feedback settings*

Footswitch = Infinite feedback


*Toggle left = always some feedback, footswitch = max feedback and silences input

Toggle middle = usually no feedback, footswitch = max feedback with input still present

Toggle left = usually no feedback, footswitch = max feedback and silences input


#define LED 3
#include <Bounce.h>
#include "effect_lofi_delay.h"

#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>

// GUItool: begin automatically generated code
AudioInputI2S            i2s1;           //xy=125,163
AudioEffectLofiDelay         lofidelay1;         //xy=223,379
AudioMixer4              mixer4; //xy=421,152
AudioEffectFade          fade6; //xy=437,546
AudioEffectFade          fade4; //xy=438,441
AudioEffectFade          fade5; //xy=438,496
AudioEffectFade          fade3; //xy=439,392
AudioEffectFade          fade1;          //xy=440,272
AudioEffectFade          fade2; //xy=440,327
AudioMixer4              mixer2; //xy=639,473
AudioMixer4              mixer1;         //xy=640,384
AudioMixer4              mixer3; //xy=794,414
AudioEffectBitcrusher    bitcrusher1;    //xy=982,411
AudioFilterBiquad        biquad1;        //xy=1150,409
AudioOutputI2S           i2s2;           //xy=1307,406
AudioConnection          patchCord1(i2s1, 0, mixer4, 0);
AudioConnection          patchCord2(lofidelay1, 0, fade1, 0);
AudioConnection          patchCord3(lofidelay1, 1, fade2, 0);
AudioConnection          patchCord4(lofidelay1, 2, fade3, 0);
AudioConnection          patchCord5(lofidelay1, 3, fade4, 0);
AudioConnection          patchCord6(lofidelay1, 4, fade5, 0);
AudioConnection          patchCord7(lofidelay1, 5, fade6, 0);
AudioConnection          patchCord8(mixer4, lofidelay1);
AudioConnection          patchCord9(fade6, 0, mixer2, 1);
AudioConnection          patchCord10(fade4, 0, mixer1, 3);
AudioConnection          patchCord11(fade5, 0, mixer2, 0);
AudioConnection          patchCord12(fade3, 0, mixer1, 2);
AudioConnection          patchCord13(fade1, 0, mixer1, 0);
AudioConnection          patchCord14(fade2, 0, mixer1, 1);
AudioConnection          patchCord15(mixer2, 0, mixer3, 1);
AudioConnection          patchCord16(mixer1, 0, mixer3, 0);
AudioConnection          patchCord17(mixer3, 0, mixer4, 1);
AudioConnection          patchCord18(mixer3, bitcrusher1);
AudioConnection          patchCord19(bitcrusher1, biquad1);
AudioConnection          patchCord20(biquad1, 0, i2s2, 0);
AudioControlSGTL5000     sgtl5000_1;     //xy=880,637
// GUItool: end automatically generated code

Bounce footswitch = Bounce(0, 50);  // debounce the footswitch
Bounce D1 = Bounce(1, 50);          // debounce the toggle switch
Bounce D2 = Bounce(2, 50);          // "  "  "  "  "  "  "  "  "

// this section includes the function to check the toggle position
bool right;
bool middle;
bool left;
void checkToggle () {               // this is our function to check toggle position...
D1.update();  D2.update();          // check digital inputs connected to toggle (can delete I think)
if(digitalRead(1) && !digitalRead(2))   {right = 1; middle = 0; left = 0;}    // toggle is right
if(digitalRead(1) && digitalRead(2))  {right = 0; middle = 1; left = 0;}      // toggle is in the middle
if(!digitalRead(1) && digitalRead(2))   {right = 0; middle = 0; left = 1;}    // toggle is left
}

uint16_t delay_max = 65535; // number of samples at 44100 samples a second
int16_t delay_line[65535] = {};
uint16_t delaytime = 1000;

// glitch variables
void fadeout();
void fadein();

//unsigned int glitchtime = 300;
unsigned int fadetime = 25;
unsigned int density = 50;

unsigned int n_time;
unsigned int sub_time;
unsigned int up_time;

unsigned long currentMillis = millis();

byte whichfade = 0;   // 0 is fade in fade1, fade out 2, fade out 3. etc...
byte lastfade = 1;

//crush
uint16_t samplerate;

uint16_t lpf;

float octup;
float octdown;
float feedback;


void setup() {
 
  AudioMemory(40); // the "40" represents how much internal memory (in the Teensy, not the external RAM chip) is allotted for audio recording. It is measured in sample blocks, each providing 2.9ms of audio.
  sgtl5000_1.enable();    // this turns on the SGTL5000, which is the audio codec on the audio board
  sgtl5000_1.volume(1);   // this sets the output volume (it can be between 0 and 1)
  sgtl5000_1.inputSelect(AUDIO_INPUT_LINEIN); // selects the audio input, we always use Line In
  analogReadResolution(12); // configure the pots to give 12 bit readings
  pinMode(0, INPUT_PULLUP); // internal pull-up resistor for footswitch
  pinMode(1, INPUT_PULLUP); // internal pull-up resistor for toggle
  pinMode(2, INPUT_PULLUP); // internal pull-up resistor for toggle
  pinMode(3, OUTPUT);       // pin 3 (the LED) is an output;
  Serial.begin(9600);       // initiate the serial monitor. USB is always 12 Mbit/sec
  analogReadAveraging(32);  

  sgtl5000_1.adcHighPassFilterDisable();
  sgtl5000_1.audioPostProcessorEnable();
  sgtl5000_1.audioPreProcessorEnable();
  sgtl5000_1.autoVolumeEnable();

  lofidelay1.acidMode(1);
  lofidelay1.begin(delay_line, delay_max);
  

  
  // output mixers
  mixer1.gain(0,1);
  mixer1.gain(1,1);
  mixer1.gain(2,1);
  mixer1.gain(3,1);

  mixer2.gain(0,1);
  mixer2.gain(1,1);

  mixer3.gain(0,1);
  mixer3.gain(1,1);

  // feedback mixer
  mixer4.gain(0,1);
  mixer4.gain(1,0);

  //initialise delays
  sub_time = (analogRead(A0) >> 2) + 50;
  n_time = sub_time ;
  up_time = sub_time / 2;
  lofidelay1.setdelay(0, n_time);  
  lofidelay1.setdelay(1, n_time);  
  lofidelay1.setdelay(2, sub_time);
  lofidelay1.setdelay(3, sub_time);
  lofidelay1.setdelay(4, up_time); 
  lofidelay1.setdelay(5, up_time);

  bitcrusher1.bits(16);  
  bitcrusher1.sampleRate(44100); 
  
}



void loop() {

  //delay / glitch times
  sub_time = (analogRead(A0) >> 2) + 50;
  n_time = sub_time ;
  up_time = sub_time / 2;

  if(millis() - currentMillis >= sub_time)              // time to glitch
  {

    density = analogRead(A2);
    if(density >= random(4095))
    {
      digitalWrite(LED, HIGH); 
          
      fadeout();

      lastfade = whichfade;
      while(whichfade == lastfade)
      {whichfade = random(6);}
      
      fadein();
    }
    currentMillis = millis();    
  }

  // crush
  samplerate = (analogRead(A3) * 5) + 1000;
  bitcrusher1.sampleRate(samplerate); 

  // filter
  lpf = (analogRead(A1) * 2) + 1000 ;                               // 1000 to ~9000 hz.  ("analogRead(A1)"  will return values from 0 to 4095
  biquad1.setLowpass(0, lpf, 0.7);                                  // q = 0.7
    
  // footswitch
  if(!digitalRead(0))  
  {
    checkToggle();
    if(left) {mixer4.gain(0,1); mixer4.gain(1,1);}                  // turn on feedback
    if(middle) {mixer4.gain(0,1); mixer4.gain(1,1);}
    if(right) {mixer4.gain(0,0); mixer4.gain(1,1);}
  }
  else 
  { 
    checkToggle();
    if(left) {mixer4.gain(0,1); mixer4.gain(1,0.8);}                // feedback always slightly on if toggle left
    else {mixer4.gain(1,0); mixer4.gain(0,1); }                     // turn off feedback
  }

  if(millis() - currentMillis >= 20) digitalWrite(LED, LOW);        // turn LED off (flashing)
   
}


// glitch functions
void fadeout ()
{
  if(whichfade == 0) {fade1.fadeOut(fadetime);   }
  if(whichfade == 1) {fade2.fadeOut(fadetime);   }
  if(whichfade == 2) {fade3.fadeOut(fadetime); }
  if(whichfade == 3) {fade4.fadeOut(fadetime); }
  if(whichfade == 4) {fade5.fadeOut(fadetime); }
  if(whichfade == 5) {fade6.fadeOut(fadetime); }
}

void fadein ()
{
  if(whichfade == 0) {fade1.fadeIn(fadetime);  lofidelay1.setdelay(0, n_time);  }
  if(whichfade == 1) {fade2.fadeIn(fadetime);  lofidelay1.setdelay(1, n_time);  }
  if(whichfade == 2) {fade3.fadeIn(fadetime);  lofidelay1.setdelay(2, sub_time);}
  if(whichfade == 3) {fade4.fadeIn(fadetime);  lofidelay1.setdelay(3, sub_time);}
  if(whichfade == 4) {fade5.fadeIn(fadetime);  lofidelay1.setdelay(4, up_time); }
  if(whichfade == 5) {fade6.fadeIn(fadetime);  lofidelay1.setdelay(5, up_time); }
}


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