Getting Started

Chapter 10: C Structures

PORTD = ~0x02;

break;

break;

PORTD = ~0x08;

break;

PORTD = ~0x10;

break;

rrent state is the value of PORTD. The input is the

tement for the specific joystick input sets the next

t is enclosed in a for(;;){}block, the

known, so the possibilities are finite and

e machine. What could be simpler? (Usually said

x.)

t of the box does a lot of stuff. And it has a lot of

enu state machine, which is

ation

case KEY_NEXT :

case KEY_PREV :

PORTD = ~0x04;

case KEY_MINUS :

case KEY_ENTER :

default:

}

This is a state machine. The cu
joystick position. The case sta
state in PORTD. If this switch statemen
Butterfly’s states and transitions are all
you have yourself a finite stat
right before things get comple

But, of course, the Butterfly ou
state machines controlling its behavior. One is the m
really the core state machine as far as a user is concerned. Here is an illustr
of the Butterfly menu structure: