ADC_Atmega8

#define F_CPU 8000000UL
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include <lcd.h>
#include <stdlib.h>
#include <avr/eeprom.h>
#include <stdio.h>
#include <math.h>

char buffer[10];
char buffer1[10];
char buffer2[10];
char buffer3[10];
char buffer4[10];
char buffer5[10];
char buffer6[10];

volatile uint16_t motor_counter = 0;
volatile uint16_t delay_counter = 0;
volatile int MENU;
volatile float values;
volatile uint16_t on_timer_value = 5;
volatile uint16_t off_timer_value = 5;
volatile float f,ff; // live current load
volatile float f1 = 2.2; // less than amp float values
volatile float f2 = 3.0; // greater than amp float values


volatile uint8_t x = 0, y = 0, z = 0, x1 = 0, ESD = 0;

ISR(ADC_vect)
{
    f = ((ADC * 0.0049) - 2.52);
}

int main(void)
{

    DDRB = 0x00; // ALL PORT I/O ARE INPUT
    PORTB = 0b00111111; // ENABLE PULL UP FOR ALL INPUT PINS
    DDRC = 0xEE; // all port c i/o are output, C0 AND C4 ARE INPUT
    PORTC |=(1<<4); // TURN ON PULL FOR PORTC PIN 4 MANUAL START BUTTON
    DDRD = 0XFF; // ALL PORTD OUTPUT DIGITAL
    InitTimer1();
    lcd_init(LCD_DISP_ON);
     lcd_puts("SYSTEM INIT....");
     _delay_ms(500);
     lcd_clrscr();
    lcd_screen_backlight_on();


// A2D Conversion Initialization
   ADCSRA |= (1 << ADPS2)|(1 << ADPS1); // Set ADC prescalar to 64 @ 8mhz

   ADMUX |= (1 << REFS0); // Set ADC reference to AVCC
  // ADMUX |= (1 << ADLAR); // Left adjust ADC result to allow easy 8 bit reading


   // No MUX values needed to be changed to use ADC0
   ADCSRA |= (1 << ADIE);
   ADCSRA |= (1 << ADFR);  // Set ADC to Free-Running Mode
   ADCSRA |= (1 << ADEN);  // Enable ADC
   ADCSRA |= (1 << ADSC);  // Start A2D Conversions

   // A2D Conversion Initialization

while(1)
{
        lcd_gotoxy(0,0);
        lcd_puts("MOTOR CURRENT");
        lcd_gotoxy(0,1);
        ff = f/0.066;

        float avg = 0;
        for(int i=0;i<1000;i++)
        {
            avg = avg + (ff)/1000;
        }
        sprintf(buffer3, "%f", ff);
        lcd_puts(buffer3);
}