Added defines for switch interval and duration.

code/main.c

 #include <avr/io.h>
 #include <util/delay.h>
 
-
+#define INTERVAL 10000 // switch interval in ms
+#define DURATION 3000 // switch duration in ms
 
 int main(void) {
 	DDRB = 0x01;
 	PORTB = 0x3e;
 	while(1) {
 		PORTB |= (1 << PB0);
-		_delay_ms(3000);
+		_delay_ms(DURATION);
 	    PORTB &= ~(1 << PB0);
-		_delay_ms(10000);
+		_delay_ms(INTERVAL);
 	}
 	return 0;
 }