Arduino-Pedal-Effects/c/multi-effects.ino

// CC-by-www.Electrosmash.com
// Based on OpenMusicLabs previous works.
// multi-effects.c including
 
//defining hardware resources.
#define LED 13
#define FOOTSWITCH 12
#define TOGGLE 2
#define PUSHBUTTON_1 A5
#define PUSHBUTTON_2 A4

//defining the output PWM parameters
#define PWM_FREQ 0x00FF // pwm frequency - 31.3KHz
#define PWM_MODE 0 // Fast (1) or Phase Correct (0)
#define PWM_QTY 2 // 2 PWMs in parallel

//other variables
int input;
int counter=0;
int effect=0;
int toggle_position=0;
byte ADC_low, ADC_high;

//effects variables:
int vol_variable=10000;
int distortion_threshold=6000;
int fuzz_threshold=6000;
int bit_crush_variable=0;

 
void setup() {
  //setup IO
  pinMode(FOOTSWITCH, INPUT_PULLUP);
  pinMode(TOGGLE, INPUT_PULLUP);
  pinMode(PUSHBUTTON_1, INPUT_PULLUP);
  pinMode(PUSHBUTTON_2, INPUT_PULLUP);
  pinMode(LED, OUTPUT);
 
  // setup ADC
  ADMUX = 0x60; // left adjust, adc0, internal vcc
  ADCSRA = 0xe5; // turn on adc, ck/32, auto trigger
  ADCSRB = 0x07; // t1 capture for trigger
  DIDR0 = 0x01; // turn off digital inputs for adc0
 
  // setup PWM
  TCCR1A = (((PWM_QTY - 1) << 5) | 0x80 | (PWM_MODE << 1)); //
  TCCR1B = ((PWM_MODE << 3) | 0x11); // ck/1
  TIMSK1 = 0x20; // interrupt on capture interrupt
  ICR1H = (PWM_FREQ >> 8);
  ICR1L = (PWM_FREQ & 0xff);
  DDRB |= ((PWM_QTY << 1) | 0x02); // turn on outputs
  sei(); // turn on interrupts - not really necessary with arduino
  
  //read the initial position of the toggle switch:
  toggle_position = digitalRead(TOGGLE);
  }
 
void loop() 
{
  //Turn on the LED if the effect is ON.
  if (digitalRead(FOOTSWITCH)) digitalWrite(LED, HIGH); 
    else  digitalWrite(LED, LOW);

  //Depending on the Toggle switch position, the effect is changed (up to 4 effects)
  if(digitalRead(TOGGLE)!=toggle_position)
    {
    toggle_position = digitalRead(TOGGLE); //update the new value
    effect++;
    if (effect>4) effect=0;
    
    //set the default variables for all effects:
    vol_variable=10000;
    distortion_threshold=6000;
    fuzz_threshold=6000;
    bit_crush_variable=0;
  }
   
}
 
ISR(TIMER1_CAPT_vect) 
{
  // get ADC data
  ADC_low = ADCL; // you need to fetch the low byte first
  ADC_high = ADCH;
  
  input = ((ADC_high << 8) | ADC_low) + 0x8000; // make a signed 16b value
  
  
 //update variables with the push-buttons  
counter++; //to save resources, the pushbuttons are checked every 100 times.
if(counter==100)
{ 
counter=0;
if (!digitalRead(PUSHBUTTON_2)) 
  {
    if (vol_variable<32768)vol_variable=vol_variable+10; //increase the volume
    if(distortion_threshold<32768)distortion_threshold=distortion_threshold+25; //increase the distortion
    if (fuzz_threshold<32768)fuzz_threshold=fuzz_threshold+25; //increase the fuzz
    if (bit_crush_variable<16)bit_crush_variable=bit_crush_variable+1; //increase the bit crushing
    digitalWrite(LED, LOW); //blinks the led
    }
 
    if (!digitalRead(PUSHBUTTON_1)) 
  {
    if (vol_variable>0)vol_variable=vol_variable-10; //decrease volume
    if (distortion_threshold>0)distortion_threshold=distortion_threshold-25; //decrease the distortion
    if (fuzz_threshold>0)fuzz_threshold=fuzz_threshold-25; //decrease the fuzz
    if (bit_crush_variable>0)bit_crush_variable=bit_crush_variable-1; //decrease the bit crushing
    digitalWrite(LED, LOW); //blinks the led
    }
}
 
 //update variables with the push-buttons 
  
  if (effect==0) //CLEAN EFFECT
    {
      //clean effect so, do nothing
    }
  //construct the input sumple summing the ADC low and high byte.
   else if(effect==1) //VOLUME EFFECT
    {
      input = map(input, -32768, +32768,-vol_variable, vol_variable);
    }
   else if(effect==2) //DISTORTION EFFECT
    {
      if(input>distortion_threshold) input=distortion_threshold;
    }
   else if(effect==3) //FUZZ EFFECT
    {
      if(input>fuzz_threshold) input=32768;
        else if(input<-fuzz_threshold) input=-32768; 
    }
   else if(effect==4) //BIT CRUSHER EFFECT
    {
  input = input<<bit_crush_variable;
    }
  
  //write the PWM signal
  OCR1AL = ((input + 0x8000) >> 8); // convert to unsigned, send out high byte
  OCR1BL = input; // send out low byte
}