/*
  State change detection (edge detection)
  2024-05-05: modified to do a Bresenham PLL ratio of pulses between the input and output
  for https://forum.arduino.cc/t/working-with-pwm/1256186/13
  https://wokwi.com/projects/397099785583173633

  Often, you don't need to know the state of a digital input all the time, but
  you just need to know when the input changes from one state to another.
  For example, you want to know when a button goes from OFF to ON. This is called
  state change detection, or edge detection.

  This example shows how to detect when a button or button changes from off to on
  and on to off.

  The circuit:
  - pushbutton attached to pin 2 from +5V
  - 10 kilohm resistor attached to pin 2 from ground
  - LED attached from pin 13 to ground through 220 ohm resistor (or use the
    built-in LED on most Arduino boards)

  created  27 Sep 2005
  modified 30 Aug 2011
  by Tom Igoe

  This example code is in the public domain.

  https://docs.arduino.cc/built-in-examples/digital/StateChangeDetection/
*/

// this constant won't change:
const int buttonPin = 2;  // the pin that the pushbutton is attached to
const int ledPin = 13;    // the pin that the LED is attached to

// Variables will change:
int buttonPushCounter = 0;  // counter for the number of button presses
int buttonState = 0;        // current state of the button
int lastButtonState = 0;    // previous state of the button
int outState = LOW; //  current state of the output pulser
int lastOutState = LOW;
int outPulseCounter = 0;

// pulse ratio constants / Bresenham Algorithm variables:
// https://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm
const long percentage = 53; // try 14%, 1%, or 99% for more understanding
const long inputPPR = 600;
long outputPPR = inputPPR * percentage / 100;
long bresenhamSum = -(inputPPR / 2);

void setup() {
  // initialize the button pin as a input:
  pinMode(buttonPin, INPUT_PULLUP);
  // initialize the LED as an output:
  pinMode(ledPin, OUTPUT);
  // initialize serial communication:
  Serial.begin(115200);
  Serial.print("");
}

void loop() {
  // read the pushbutton input pin:
  buttonState = digitalRead(buttonPin);

  // compare the buttonState to its previous state
  if (buttonState != lastButtonState) {
    // if the state has changed, increment the counter
    if (buttonState == LOW) {
      // if the current state is HIGH then the button went from off to on:
      buttonPushCounter++;
      Serial.println("on");
      Serial.print("number of button pushes: ");
      Serial.println(buttonPushCounter);
      Serial.print("Bresenham Decision Sum = ");
      Serial.print(bresenhamSum);
      Serial.print("+");
      Serial.print(outputPPR);
      bresenhamSum += outputPPR;
      if (bresenhamSum > 0)
      {
        Serial.print("=");
        Serial.print(bresenhamSum);

        Serial.print(">0, so step:");
        Serial.print(bresenhamSum);
        Serial.print("-");
        Serial.print(inputPPR);
        bresenhamSum -= inputPPR;
        outState = HIGH;
        ++outPulseCounter;
      }

      Serial.print(" = ");
      Serial.println(bresenhamSum);

      Serial.print("number of outputPulses:");
      Serial.println(outPulseCounter);
      Serial.print("Ratio: ");
      Serial.println(100.0 * outPulseCounter / buttonPushCounter);

    } else {
      // if the current state is LOW then the button went from on to off:
      Serial.println("off");
      outState = LOW;
    }
    // Delay a little bit to avoid bouncing
    delay(50);
  }
  // save the current state as the last state, for next time through the loop
  lastButtonState = buttonState;


  // toggles the output to match the outState when it changes:
  if (outState != lastOutState) {
    digitalWrite(ledPin, outState);
    lastOutState = outState;
  }
}