// code modified from https://forum.arduino.cc/t/i-would-love-to-receive-help-with-frequency-transmission-using-arduino/1211551/29?u=davex
// https://wokwi.com/projects/387127367989449729

unsigned long T0;
float Hightime = 0;
float Lowtime = 0;
float frequency;
float Time;
float Duty;
float digitalPin = 7;
const byte simPin = 9;

#include <TimerOne.h>

void setup() {
  Serial.begin(115200);
  pinMode(digitalPin, INPUT);
  pinMode(9, OUTPUT);
  Timer1.initialize(250);  // 250 us = 4 kHz
  //analogWrite(simPin, 10);
  Timer1.pwm(simPin, 500);
}

void loop() {
  bool read = digitalRead(digitalPin);
  const int steps = 5;
  for (int simDuty = 1023 / (2*steps); simDuty <= 1023; simDuty += 1023 / steps) {
    while (digitalRead(digitalPin) == LOW); // wait to start
    T0 =  micros(); // mark the first rising
    while ( digitalRead(digitalPin) == HIGH); // wait to fall
    Hightime = micros() - T0; //measure the high time;
    while ( digitalRead(digitalPin) == LOW);
    Time = micros() - T0; // measure the total time

    frequency = 1000000 / Time ;
    Duty = Hightime / Time;
    Serial.print("Tus:");
    Serial.print(Time);
    Serial.print(" f:");
    Serial.print(frequency);
    Serial.print(" HighUs:");
    Serial.print(Hightime);
    Serial.print(" d%:");
    Serial.println(Duty*100, 2);
    
    Timer1.pwm(simPin, simDuty); // change the duty cycle sim
    delay(777); // pause for viewing
    while (digitalRead(digitalPin) == HIGH); // wait again
  }
}