TIMER PULSE

// Include necessary libraries
#include <Arduino.h>

// Define the pins for various components
const int outputPin = 9;         // Digital pin to output the square wave
const int leftButtonPin = 2;     // Digital pin for the left button
const int rightButtonPin = 3;    // Digital pin for the right button
const int redLightPin = 13;      // Digital pin for the red light indicator

// Declare the frequency variable and frequency limits
volatile unsigned long frequency = 10000; // Initial frequency in Hz (10 kHz)
unsigned long minFrequency = 1000;        // 1 kHz minimum frequency
unsigned long maxFrequency = 20000;       // 20 kHz maximum frequency

// Setup function runs once when the Arduino starts
void setup() {
  // Set pin modes for various components
  pinMode(outputPin, OUTPUT);                // Output pin for the square wave
  pinMode(leftButtonPin, INPUT_PULLUP);      // Input pin for the left button
  pinMode(rightButtonPin, INPUT_PULLUP);     // Input pin for the right button
  pinMode(redLightPin, OUTPUT);              // Output pin for the red light indicator

  // Attach interrupt functions to the buttons
  attachInterrupt(digitalPinToInterrupt(leftButtonPin), decreaseFrequency, FALLING);
  attachInterrupt(digitalPinToInterrupt(rightButtonPin), increaseFrequency, FALLING);

  // Disable interrupts temporarily and initialize timer
  noInterrupts();
  timer1_init(100); // Timer period in milliseconds
  interrupts();
  
  // Initialize serial communication for debugging
  Serial.begin(9600);
}

// Loop function continuously runs after setup
void loop() {
  // No code needed in the loop
}

// Timer interrupt service routine (ISR)
ISR(TIMER1_COMPA_vect) {
  digitalWrite(outputPin, !digitalRead(outputPin)); // Toggle the output pin to generate square wave
}

// Initialize timer1 with given period in milliseconds
void timer1_init(int msec) {
  TCCR1A = 0;          // Clear Timer1 configuration A register
  TCCR1B = 0;          // Clear Timer1 configuration B register
  TCNT1 = 0;           // Initialize the timer count value
  OCR1A = (int)(F_CPU / (2 * 1024.0 * 1000 / frequency)) - 1; // Set compare value for desired frequency

  TCCR1B |= (1 << WGM12); // Set Timer1 to CTC mode
  TCCR1B |= (1 << CS12) | (1 << CS10); // Set prescaler to 1024
  TIMSK1 |= (1 << OCIE1A); // Enable Timer1 compare interrupt
}

// Function to decrease frequency by 10% when left button is pressed
void decreaseFrequency() {
  frequency -= frequency * 0.1; // Decrease frequency by 10%
  updateFrequency(); // Update the frequency and related components
}

// Function to increase frequency by 10% when right button is pressed
void increaseFrequency() {
  frequency += frequency * 0.1; // Increase frequency by 10%
  updateFrequency(); // Update the frequency and related components
}

// Function to update frequency and handle limit checks
void updateFrequency() {
  if (frequency < minFrequency) {
    frequency = minFrequency;
    digitalWrite(redLightPin, HIGH); // Turn on the red light indicator if below minimum frequency
  } else if (frequency > maxFrequency) {
    frequency = maxFrequency;
    digitalWrite(redLightPin, HIGH); // Turn on the red light indicator if above maximum frequency
  } else {
    digitalWrite(redLightPin, LOW); // Turn off the red light indicator within frequency range
  }

  // Update the timer with the new frequency
  timer1_init(100);
  
  // Print the updated frequency to the serial monitor
  Serial.print("Frequency: ");
  Serial.print(frequency);
  Serial.println(" Hz");
}