#include <avr/io.h>

      #include <util/delay.h>

      //-------------------------------------

      void m_delay_10ms(unsigned long val) {

      //-------------------------------------

                 while(val--) _delay_ms(10);

      }

             

      //-------------------------------------

      void do_delay(uint16_t ms_delay, uint16_t num_ms, uint16_t us_delay, uint16_t num_us)  {

      //-------------------------------------

              uint16_t i;

       

              for(i=0;i<num_ms;i++) _delay_ms(250);

              for(i=0;i<ms_delay;i++) _delay_ms(1);

              for(i=0;i<num_us;i++) _delay_us(250);

              for(i=0;i<us_delay;i++) _delay_us(1);

      }
  
       

      //-------------------------------------

      void generate_tone(uint16_t frequency, uint16_t duration)

      //-------------------------------------

      {

                uint32_t total_delay_time;

                uint16_t total_ms_delay_time, total_us_delay_time;

                uint16_t num_us_delays, num_ms_delays, ms_delay_time, us_delay_time;

                uint16_t num_periods;

                total_delay_time = (1000000/frequency)/2-10;

                total_ms_delay_time = total_delay_time/1000;

                num_ms_delays = total_ms_delay_time/250;

                ms_delay_time = total_ms_delay_time%250;

                total_us_delay_time = total_delay_time%1000;

                num_us_delays = total_us_delay_time/250;

                us_delay_time = total_us_delay_time%250;

                num_periods = ((uint32_t)duration*1000)/(1000000/frequency);

                while((num_periods--) != 0)

                {
 
                   do_delay(ms_delay_time, num_ms_delays, us_delay_time, num_us_delays);

                   PORTB |=  (1<<PINB3);

                   do_delay(ms_delay_time, num_ms_delays, us_delay_time, num_us_delays);

                   PORTB &= ~(1<<PINB3);

                }

       

                return;

      }

      //-------------------------------------

      int main(void) {

      //-------------------------------------

                 DDRB = (1<<PINB3)|(1<<PINB0); //csak a PB3 és a PB4 kimenet

                 while(1) {

                     generate_tone(16000,200);

                     generate_tone(18000,200);

                     generate_tone(20000,200);

                     generate_tone(22000,200);

                     generate_tone(24000,200);

                     if(PORTB & (1<<PINB0)) PORTB &= ~(1<<PINB0);

                                       else PORTB |=  (1<<PINB0);
  
                     m_delay_10ms(250); //100*10ms = 1s

                 }

                 return 0;

      }