Arduino-Pedal-Effects/c/New Effects PedalSHIELD UNO/Chorus/Chorus.ino

/* Based on the "CHORUS for Stompshield" adapted from pedal shield, and reconverted for pedalSHIELD UNO*/
 
//defining harware 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

//defining buttons parameters
#define B_MAX 100 // max value for rotary encoder input (min freq)
#define B_MIN 1 // min value for rotary encoder input (max freq)

//defining FX parameters
#define MAX_DELAY 240
#define MIN_DELAY 200

uint16_t sDelayBuffer0[MAX_DELAY*2];
uint16_t sDelayBuffer1[MAX_DELAY*2];
unsigned int DelayCounter = 5;
unsigned int Delay_Depth = 25;
unsigned int count_up=1;
int p;
int POT0 = 1;


unsigned int location = 0; // incoming data buffer pointer
byte button; // button checking timer
byte last_state; // last rotary encoder state
byte counter = 1; // rotary encoder rotation counter (and start value)
unsigned int fractional = 0x00; // fractional sample position
int data_buffer; // temporary data storage to give a 1 sample buffer
int counter2=0; //buttons timer counter

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
  }

void loop() {
  // nothing happens here, all down in the interrupt
}
void checkButton()
{
counter2++; //to save resources, the pushbuttons are checked every 2000 times.
if(counter2==2000)
{ 
counter2=0;
  if (!digitalRead(PUSHBUTTON_1)) {
     if (counter > B_MIN) counter-=1; // if not at min, decrement
      }
      if (!digitalRead(PUSHBUTTON_2)) {
        if (counter < B_MAX) counter+=1; // if not at max, increment
      }
    }
}

ISR(TIMER1_CAPT_vect) { // all processing happens here

  // output the last value calculated
  OCR1AL = ((data_buffer + 0x8000) >> 8); // convert to unsigned, send out high byte
  OCR1BL = data_buffer; // send out low byte
  
  // get ADC data
  byte temp1 = ADCL; // you need to fetch the low byte first
  byte temp2 = ADCH; // yes it needs to be done this way
  int input = ((temp2 << 8) | temp1) + 0x8000; // make a signed 16b value
  
  checkButton();
//  Delay_Depth=counter;
 
  sDelayBuffer0[DelayCounter] = input;
  POT0 = counter;
  DelayCounter++;
  if(DelayCounter >= Delay_Depth) 
  {
    DelayCounter = 0; 
    if(count_up)
    {
       for(p=0;p<POT0+1;p++) 
       sDelayBuffer0[Delay_Depth+p]=sDelayBuffer0[Delay_Depth-1]; 
       Delay_Depth=Delay_Depth+POT0;
       if (Delay_Depth>=MAX_DELAY)count_up=0;
    }
    else
    {
       Delay_Depth=Delay_Depth-POT0;
       if (Delay_Depth<=MIN_DELAY)count_up=1;
    }
  }

   
 
  
  // save value for playback next interrupt
  data_buffer = sDelayBuffer0[DelayCounter];
}