How to use interrupts in microcontrollers

				
					#include <xc.h>
#include <stdint.h>

#define _XTAL_FREQ 20000000

// Configuration bits settings
#pragma config FOSC = HS        // External Oscillator (HS)
#pragma config WDTE = OFF       // Watchdog Timer Disabled
#pragma config PWRTE = ON       // Power-Up Timer Enabled
#pragma config BOREN = OFF      // Brown-out Reset Disabled
#pragma config LVP = OFF        // Low-Voltage Programming Disabled

// Pin definitions
#define Lcd_EN RD7
#define Lcd_RW RD6
#define Lcd_RS RD5

// Port definitions
#define Lcd_Port PORTC // Use PORTC for LCD data lines

// Function prototypes - See further down
void LCD_DataWrite(char dat);
void LCD_CommandWrite(char cmd);
void LCD_Initialize();
void LCD_String(const char* text);
void LCD_Clear();

volatile uint16_t counter = 0; // Declare a volatile counter variable

void __interrupt() ISR() {
    if (INTF) {
        counter++; // Increment the counter
        LCD_Clear(); // Clear the LCD screen
        char buffer[17]; // Buffer to hold the counter as a string
        sprintf(buffer, "Counter: %u", counter); // Format the counter value
        LCD_String(buffer); // Display the counter on the LCD
        INTF = 0; // Clear the RB0 external interrupt flag
    }
}

void main() {
    TRISB0 = 1; // Set RB0 as input for the external interrupt
    TRISC = 0x00; // Set PORTC as output for LCD data lines
    TRISD = 0x00; // Set PORTD as output
    PORTD = 0x00; // Clear PORTD initially

    INTCON = 0b11010000; // Enable Global Interrupt, Peripheral Interrupt, and RB0 External Interrupt, set flag to 0

    LCD_Initialize();

    while (1) {
        // Your main program logic here
    }
}

// Other functions remain the same as in the original code on:
// https://florisera.com/embedded-systems/connecting-pic16f877a-with-an-lcd-screen/

// Function to send data byte to the LCD (HD44780)
void LCD_DataWrite(char dat)
{
   Lcd_Port=dat;	  // Set the data on the PORT
   Lcd_RS=1;	      // Select the Register for sending data by pulling RS HIGH
   Lcd_RW=0;          // Select Write by pulling RW LOW
   Lcd_EN=1;	      // Send a High-to-Low Pulse at EN pin
   __delay_us(10);
   Lcd_EN=0;          // set EN pin back to LOW
   __delay_ms(2);     // Add a delay to ensure proper timing, and no need for Buffer check
}

// Function to send command to the LCD (HD44780)
void LCD_CommandWrite(char cmd)
{
   Lcd_Port=cmd;	  // Set the data on the PORT
   Lcd_RS=0;	      // Select the Register for sending a command by pulling RS LOW
   Lcd_RW=0;          // Select Write by pulling RW LOW
   Lcd_EN=1;	      // Send a High-to-Low Pulse at EN pin
   __delay_us(10);
   Lcd_EN=0;          // set EN pin back to LOW
   __delay_ms(2);     // Add a delay to ensure proper timing, and no need for Buffer check
}

// Function to initialize the LCD
void LCD_Initialize()
{
    __delay_ms(15);    // 15 ms start up time, as per datasheet
    LCD_CommandWrite(0x38); // "Function set": 8-bit data, 2-line display, 5x8 font. 0b00111000
    LCD_CommandWrite(0x0C); // "Display on/off": Display on, cursor off, blinking off. 0b00001100
    LCD_CommandWrite(0x01); // "Clear Display":  Clear display. 0b00000001
    LCD_CommandWrite(0x06); // "Entry mode set": cursor increments, no display shift. 0b00000110
}

void LCD_String(const char* text) {
    int charIndex = 0;

    while (text[charIndex] != '\0') { //continue incrementing untill it reaches the null
        LCD_DataWrite(text[charIndex]);

        // Check if the text is longer than 16 characters & does not have a null on the 17th character
        if (charIndex == 15 && text[16] != '\0') {
            LCD_CommandWrite(0xC0); // Set DDRAM address to second line
        }

        charIndex++;
    }
}

void LCD_Clear() {
    LCD_CommandWrite(0x01); // Clear display
    __delay_ms(2);
}