/*
 *  Name:    OT_dutycycle
 *  Purpose: Measures dutycycle of measured OT signals.
 *  Author:  Martijn van den Burg
 *
 */ 
#include <avr/interrupt.h>
#include <avr/io.h>

#define TIMER_RESET  TCNT1 = 0
#define SAMPLE_SIZE  64

int OTpin = 2;

unsigned int TimeLow[SAMPLE_SIZE];
unsigned int TimeHigh[SAMPLE_SIZE];

char direction[SAMPLE_SIZE];
byte change_count;

long temp;
long time;
long AvgLow;
long AvgHigh;
long TotalLow;
long TotalHigh;
long dutycycle;


void setup() {
  Serial.begin(115200);
  Serial.println("Analyze OT dutycycle");
  TCCR1A = 0x00;          // COM1A1=0, COM1A0=0 => Disconnect Pin OC1 from Timer/Counter 1 -- PWM11=0,PWM10=0 => PWM Operation disabled
  // ICNC1=0 => Capture Noise Canceler disabled -- ICES1=0 => Input Capture Edge Select (not used) -- CTC1=0 => Clear Timer/Counter 1 on Compare/Match
  // CS12=0 CS11=1 CS10=1 => Set prescaler to clock/64
  TCCR1B = 0x03;          // 16MHz clock with prescaler means TCNT1 increments every 4uS
  // ICIE1=0 => Timer/Counter 1, Input Capture Interrupt Enable -- OCIE1A=0 => Output Compare A Match Interrupt Enable -- OCIE1B=0 => Output Compare B Match Interrupt Enable
  // TOIE1=0 => Timer 1 Overflow Interrupt Enable
  TIMSK1 = 0x00;          
  pinMode(OTpin, INPUT);
}

void loop()  {
  
  Serial.println("Waiting...");
  change_count = 0;
  TotalLow = 0;
  TotalHigh = 0;
  int i = 0;
  int j = 0;
  int n = 0;
  
  while(digitalRead(OTpin) == LOW) {}

  Serial.println("Sampling...");

  TIMER_RESET;

  direction[change_count++] = '0';

  while (change_count < SAMPLE_SIZE) {
    temp = TCNT1;

    if (direction[change_count-1] == '0') {
      while(digitalRead(OTpin) == LOW) {}
      TimeLow[i] = TCNT1 - temp;
      direction[change_count++] = '1';
      i++;
    } 
    else {
      while(digitalRead(OTpin) == HIGH) {}
      TimeHigh[j] = TCNT1 - temp;
      direction[change_count++] = '0';
      j++;
    }
    
  }


  for (int i = 0; i < SAMPLE_SIZE / 2; i++) {
    time = (long) TimeLow[i] * 4;
    if (time < 1300 && time > 0) {
      n++;
      TotalLow += time;
    }
  }
  AvgLow = (float)TotalLow / n;

  n = 0;

  for (int i = 0; i < SAMPLE_SIZE / 2; i++) {
    n++;
    time = (long) TimeHigh[i] * 4;
    if (time < 1300 & time > 0) {
      TotalHigh += time;
    }
  }
  AvgHigh = (float)TotalHigh / n;


  dutycycle = (float)TotalHigh / (TotalHigh + TotalLow) * 100;
  
  Serial.print("Duty cycle: ");
  Serial.print(dutycycle);
  Serial.println(" %");
  Serial.print("Average time LOW: ");
  Serial.println(AvgLow);
  Serial.print("Average tome HIGH: ");
  Serial.println(AvgHigh);
  Serial.println("");


  Serial.println("Done");
  delay(2000);
}