State Machines

State Machines can be represented like this:

To the right is an example of a state machine for a bomb. To the bottom is the exact same state machine, but represented in C code. C code is great for representing state machines because of the enumeration function. We can define a new type with all of the states and another for all the events.

typedef enum {

    NO_EVENT, PUSHED_ARM, PUSHED_DISARM

} event_t

typedef enum {

    INITIAL_STATE, DISARMED, COUNTING_DOWN, WE_GO_BOOM

} state_t

void RunStateMachine (event_t currentEvent){

    static int count = 0

    static state_t currentState = INITIAL_STATE;

    switch (currentState){

    case INITIAL_STATE:{

        currentState = DISARMED;

        break;

    case DISARMED:{

        switch (currentEvent){

        case PUSHED_ARM:

            TIMERS_InitTimer(BOMB_TIMER, BOMB_INTERVAL);

            count = 12

            currentState = COUNTING_DOWN;

            break;

    case COUNTING_DOWN:{

        switch (currentEvent){

        case TIMEOUT:

            count--;

            //update LEDs

            TIMERS_InitTimer(BOMB_TIMER, BOMB_INTERVAL);

            if (count == 0){

                currentState = WE_GO_BOOM;

            break;

        case PUSHED_DISARM:

            currentState = DISARMED;

            TIMER_Stop_Timer(BOMB_TIMER)

    case WE_GO_BOOM:

        printf("Boom!");

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