// hack of the state change detection example for 
// forum https://forum.arduino.cc/t/controlling-an-ignition-coil-with-arduino/1103573
// https://wokwi.com/projects/359585642842082305

// Pin 5 is a simulated 50% duty cycle singla with frequency dependent on A0
// A0 is a pot to control the frequency of Pin 5. 31Hz-100Hz, 
// (31Hz low because of tone() limit
// Pin 2 is the input signal
// Pin 3 is thr output pulse, a 4ms long one-shot triggered by the input 
// and desgined to end at the same time as the input pulse.

/*
  State change detection (edge detection)

  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://www.arduino.cc/en/Tutorial/BuiltInExamples/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
const int coilPin = 3;       // the pin that the LED is attached to
const int throttlePotPin = A0;
const int tonePin = 5;

// 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 lastThrottleValue = 0;


unsigned long nowMicros = 0, lastOn = 0, lastOff = 0, lastOnPeriod = 0, lastOffPeriod = 0, offInterval;
// coil pulse variables
bool armed = false, triggered = false;
unsigned long triggerTime = 0;
unsigned long pulseWidthUs = 4000-100;

void setup() {
  // initialize the button pin as a input:
  pinMode(buttonPin, INPUT);
  // initialize the LED as an output:
  pinMode(ledPin, OUTPUT);
  pinMode(coilPin, OUTPUT);
  // initialize serial communication:
  Serial.begin(9600);
}


void loop() {
  // read the pushbutton input pin:
  nowMicros = micros();
  buttonState = digitalRead(buttonPin);
  int throttleValue = map(analogRead(A0), 0, 1023, 31, 100);
  if (throttleValue != lastThrottleValue) {
    lastThrottleValue = throttleValue;
    Serial.print("Throttle:");
    Serial.println(throttleValue);
    tone(tonePin, throttleValue);
  }

  // compare the buttonState to its previous state
  if (buttonState != lastButtonState) {
    // if the state has changed, increment the counter
    if (buttonState == HIGH) { // rising edge
      // 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);
      lastOffPeriod = nowMicros - lastOff;
      lastOn = nowMicros;
      offInterval = lastOffPeriod - pulseWidthUs; //
      armed = true;
      //Serial.print('^');
      //Serial.print(offInterval);
    } else { // falling edge
      // if the current state is LOW then the button went from on to off:
      //Serial.println("off");
      lastOnPeriod = nowMicros-lastOn;
      lastOff = nowMicros;
      //Serial.print('v');

    }
    // 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;


  if (armed && (nowMicros - lastOn > offInterval)) {
  //if (armed ) {
    digitalWrite(coilPin, HIGH);
    armed = false;
    triggered = true;
    triggerTime = nowMicros;
    //digitalWrite(ledPin,HIGH);
    //Serial.print('+');
  }
  if (triggered && nowMicros - triggerTime >= pulseWidthUs) {
    digitalWrite(coilPin, LOW);
    triggered = false;
    //digitalWrite(ledPin,LOW);
    //Serial.print('.');
  }



  // turns on the LED every 100 button pushes by checking the modulo of the
  // button push counter. the modulo function gives you the remainder of the
  // division of two numbers:
  if (buttonPushCounter % 100 == 0) {
    digitalWrite(ledPin, !digitalRead(ledPin));
  }
  report();
}

void report() {
  static uint32_t last;
  if (millis() - last < 1000) return;
  last = millis();
  Serial.print("  InputPulses:");
  Serial.print(buttonPushCounter);
  Serial.print("  Period:");
  Serial.print(lastOffPeriod+lastOnPeriod);
  Serial.print("us  offInterval:");
  Serial.print(offInterval);
  Serial.println("us");

}