#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <Arduino.h>
#include <esp_timer.h>

const int signalPin = 4;
volatile uint32_t pulseCount = 0;
volatile float frequency = 0.0;
esp_timer_handle_t timer;

LiquidCrystal_I2C lcd(0x27, 16, 2);

void IRAM_ATTR countPulse() {
    pulseCount++;
}

void IRAM_ATTR timerCallback(void* arg) {
    frequency = pulseCount;
    pulseCount = 0;
}

void setup() {
    Serial.begin(115200);
    pinMode(signalPin, INPUT_PULLUP);
    attachInterrupt(signalPin, countPulse, RISING);

    esp_timer_create_args_t timerConfig = {
        .callback = &timerCallback,
        .arg = NULL,
        .dispatch_method = ESP_TIMER_TASK,
        .name = "Frequency_Timer"
    };
    esp_timer_create(&timerConfig, &timer);
    esp_timer_start_periodic(timer, 1000000);

    lcd.init();
    lcd.backlight();
    lcd.setCursor(0, 0);
    lcd.print("Frequency:");
}

void loop() {
    Serial.print("Frequency: ");
    Serial.print(frequency);
    Serial.println(" Hz");

    lcd.setCursor(0, 1);
    lcd.print(frequency);
    lcd.print(" Hz   ");

    delay(1000);
}