OCR0A = 0; // set PWM to full brightness
SPDR = 0b00000001; // select first LED
while(!(SPSR & (1<<SPIF))); // write to shift register
PORTB = 0; // latch outputs
PORTB = 1;
_delay_ms(1);

OCR0A = 255; // set PWM to no brightness (off)
SPDR = 0b00000010; // select second LED
while(!(SPSR & (1<<SPIF)));
PORTB = 0;
PORTB = 1;
_delay_ms(1);

OCR0A = 255; // set PWM to no brightness (off)
_delay_a_little_more;
SPDR = 0b00000001; // select first LED
while(!(SPSR & (1<<SPIF))); // write to shift register
PORTB = 0; // latch outputs
PORTB = 1;
OCR0A = 0; // set PWM to full brightness
_delay_ms(1);

OCR0A = 255; // set PWM to no brightness (off)
_delay_a_little_more;
SPDR = 0b00000010; // select second LED
while(!(SPSR & (1<<SPIF)));
PORTB = 0;
PORTB = 1;
OCR0A = 255; // set PWM to no brightness (off)
_delay_ms(1);