// https://wokwi.com/projects/448822516009346049
// https://forum.arduino.cc/t/control-system-and-ui-control-rc-servo-according-to-incoming-pulses-from-inductive-sensor/1416579

# include <Servo.h>
Servo theServo;

# define thePulse 2  // input pulses on pin 2

# define ONOFF 3     // do or don't

// as periods in microseconds
const unsigned long minPulse = 34468ul;  // ~30 Hz, low end
const unsigned long maxPulse = 2868ul;   // ~350 Hz, high end

// corresponding servo degrees
const int minDeflection = 5;
const int maxDeflection = 175;

# define PARK   60  // when off, park here

float minFrequency;
float maxFrequency;

Servo myservo;  // create servo object to control a servo
// twelve servo objects can be created on most boards

int pos = 0;    // variable to store the servo position

void setup() {
  Serial.begin(115200);
  Serial.println("\nCrude frequency -> servo pos.\n");

  theServo.attach(9);  // attaches the servo on pin 9 to the servo object

  pinMode(ONOFF, INPUT_PULLUP);

  pinMode(thePulse, INPUT_PULLUP);  // Set interrupt pin as input with internal pull-up resistor
  attachInterrupt(digitalPinToInterrupt(thePulse), pulseISR, RISING);

  minFrequency = 1.0 / maxPulse;
  maxFrequency = 1.0 / minPulse;
}

volatile unsigned long edgeToEdge;

// each rising edge triggers this function
void pulseISR() {
  static unsigned long lastEdge;
  unsigned long thisEdge;

  thisEdge = micros();
  edgeToEdge = thisEdge - lastEdge;

  lastEdge = thisEdge;
}

// a little Algebra
float fmap(float x, float in_min, float in_max, float out_min, float out_max) {
  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}

void loop() {
  if (digitalRead(ONOFF) == LOW) {
    theServo.write(PARK);
    
    return;   // we done!
  }

// else... check if there's a plausible measurement and move the servo accordianly

  unsigned long now = millis();  // the time for this entire pass

  noInterrupts();
  unsigned long myE2E = edgeToEdge;
  interrupts();

  if (maxPulse <= myE2E && myE2E <= minPulse) {
    float frequency = 1.0 / myE2E;
    int deflection = fmap(frequency, minFrequency, maxFrequency, minDeflection, maxDeflection);
    theServo.write(deflection);
  }

// periodically print the edgeToEdge value
// as a check
  static unsigned long lastCheck;
  if (now - lastCheck > 777) {
    Serial.println(myE2E);
    lastCheck = now;
  }
}








// turtles all the way down

// from the wokwi demo for the pulse generator IC
/*
  Flow Sensor Counter Meter FS300A G3/4
  Flow rate :   1-60L/min
  Flow Pulse:   508 pulse / Liter
  Description: This code interfaces with the FS300A flow sensor to measure flow rate and frequency. It handles interrupt-driven pulse counting and calculates the corresponding flow rate based on the sensor specifications.


#define  FS300A_PULSE     508         // Number of pulses per liter
#define  FS300A_FLOW_RATE 60          // Maximum flow rate in liters per minute
const float factor = 60.0F / 508.0F;  // Conversion factor from pulses to flow rate (FS300A_FLOW_RATE / FS300A_PULSE)

#define interruptPin 2  // Define interrupt pin for flow sensor

uint16_t pulse;         // Variable to store pulse count
uint16_t count;         // Variable to store pulse count for calculation

float frequency;        // Variable to store frequency
float flowRate;         // Variable to store flow rate

bool busy;              // Flag to indicate interrupt handling status

void setup() {
  Serial.begin(115200);  // Initialize serial communication at 115200 baud

  pinMode(interruptPin, INPUT_PULLUP);  // Set interrupt pin as input with internal pull-up resistor
  attachInterrupt(digitalPinToInterrupt(interruptPin), FlowInterrupt, CHANGE);  // Attach interrupt handler to the interrupt pin
}

void loop() {
  Frequency();  // Call frequency measurement function
}

void FlowInterrupt() {
  busy = true;  // Set busy flag to indicate interrupt handling
  pulse++;      // Increment pulse count
  busy = false; // Clear busy flag after interrupt handling
}

void Frequency() {
  static unsigned long startTime;
  if (micros() - startTime < 1000000UL ) return;   // Check if 1000 milliseconds interval has passed
  startTime = micros();

  while (busy) {};  // Wait for interrupt handling to complete

  uint8_t sreg = SREG;  // Save status register
  cli();                // Disable interrupts
  count = pulse;        // Save pulse count for calculation
  pulse = 0;            // Reset pulse count
  SREG = sreg;          // Restore status register

  frequency = count / 2.0f;       // Calculate frequency
  flowRate = frequency * factor;  // Calculate flow rate

  PlotInfo();  // Display information
}

void PlotInfo() {
  Serial.print("Freq.:= " + String(frequency, 2) + " Hz");        // Print frequency with 2 decimal places
  Serial.println(", FLow:= " + String(flowRate, 3) + " L/min");   // Print flow rate with 3 decimal places
}
*/

//;
;
//;