... /******TIMER INTERUPTS**********/ SIGNAL (SIG_OVERFLOW0){ char sreg; sreg = SREG; //Piezo signal as debug for(counter=0;counter<5;counter++){ PORTB=0x00; PORTB=0x20; } Usart_Tx(a); TCNT0=0x40; SREG = sreg; } SIGNAL (SIG_OUTPUT_COMPARE0){ char sreg; sreg = SREG; for(counter=0;counter<5;counter++){ PORTB=0x00; PORTB=0x20; } Usart_Tx('x'); SREG = sreg; } /**********END TIMER INTERUPTS**********/ int main(void) { DDRB = 0xff; //init the data direct register B for port B /*******CPU - PRESCALING OK**********/ //CLKPR = (1<