IR Frequency Meter

// Reference:
// https://docs.arduino.cc/language-reference/en/functions/external-interrupts/attachInterrupt/
// https://www.makerguides.com/how-to-read-fan-speed-signal-with-arduino/
// https://circuitdigest.com/microcontroller-projects/interfacing-flame-sensor-with-arduino
// https://circuitdigest.com/microcontroller-projects/arduino-frequency-counter-circuit
// https://www.instructables.com/Arduino-Frequency-Counter/
// https://github.com/Bodmer/TFT_eSPI/blob/master/examples/160%20x%20128/TFT_Print_Test/TFT_Print_Test.ino
//
//  Uses IR Infrared Flame Sensor Module 3 Pin
//  Read a IR signal and determine frequency with ESP32-C3

#include "Arduino.h"

// Pin Assignments
#define IR_Pin D10

// Variables
volatile unsigned long freq = 0;

void countPulses() { freq++; }

void setup() {
    // Initalize GPIO pins
    pinMode(IR_Pin, INPUT);

    // Initalize Serial port
    Serial.begin(9600);
  Serial.println("IR Frequency Meter");

  attachInterrupt(digitalPinToInterrupt(IR_Pin),countPulses,RISING);
  delay(500);
}

void loop() {
  delay(1000);

  Serial.print("IR Frequency: ");
  Serial.print(freq);
  Serial.println(" Hz");

  freq = 0;
}