A0_Avr_SwitchAndBuzzer.c

#include <avr/io.h>

int main()
{
    DDRC = 0xff;           // Configure PORTC as output to connect Buzzer
    DDRA = 0x00;           // Configure PORTA as Input to read the switchs
    PORTA = 0xff;          // Enable The PullUps of PORTA.
    while(1)
    {
        PORTC = PINA;     // Read the switch status and Turn ON/OFF the Buzzer
    }
    return 0;
}