Button Input Handling

Button events from the driver queue are dispatched to the state machine, which determines the appropriate response based on the current application state.

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Button → State Machine Pipeline

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Button Action Map

State	Button	Event type	Action
IDLE	BTN_SELECT	LONG_PRESS	→ MENU
IDLE	any	PRESS	(ignored)
ALARM_FIRING	BTN_SNOOZE	PRESS	→ SNOOZED; stop audio; set snooze timer
ALARM_FIRING	BTN_DISMISS	PRESS	→ IDLE; stop audio
ALARM_FIRING	BTN_UP / BTN_DOWN	PRESS	(ignored during alarm)
SNOOZED	BTN_DISMISS	PRESS	→ IDLE; clear snooze timer
MENU	BTN_UP	PRESS	scroll menu up
MENU	BTN_DOWN	PRESS	scroll menu down
MENU	BTN_SELECT	PRESS	enter selected menu item
MENU	BTN_BACK	PRESS	→ IDLE
ALARM_SET	BTN_UP	PRESS	increment selected field
ALARM_SET	BTN_DOWN	PRESS	decrement selected field
ALARM_SET	BTN_SELECT	PRESS	advance to next field; save on last field
ALARM_SET	BTN_BACK	PRESS	cancel; → MENU

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Long-Press Detection

BTN_SELECT held for >2 seconds from IDLE opens the menu. The button driver emits BTN_EVENT_LONG_PRESS when the hold duration exceeds the threshold. The main task treats it the same as a regular event:

case BTN_EVENT_LONG_PRESS:
    if (evt.id == BTN_SELECT && current_state == STATE_IDLE) {
        transition_to(STATE_MENU);
    }
    break;

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Menu Navigation

The menu is a simple list of items with a cursor position:

typedef struct {
    const char *label;
    screen_t    screen;   // screen to enter on SELECT
} menu_item_t;

static const menu_item_t menu_items[] = {
    { "Set alarm",    SCREEN_ALARM_SET },
    { "Volume",       SCREEN_VOLUME_SET },
    { "Timezone",     SCREEN_TZ_SET },
    { "WiFi setup",   SCREEN_WIFI_SETUP },
};
static int menu_cursor = 0;

void menu_handle(button_event_t evt) {
    switch (evt.id) {
        case BTN_UP:
            menu_cursor = (menu_cursor - 1 + ARRAY_LEN(menu_items)) % ARRAY_LEN(menu_items);
            request_display_update(SCREEN_MENU);
            break;
        case BTN_DOWN:
            menu_cursor = (menu_cursor + 1) % ARRAY_LEN(menu_items);
            request_display_update(SCREEN_MENU);
            break;
        case BTN_SELECT:
            transition_to_screen(menu_items[menu_cursor].screen);
            break;
        case BTN_BACK:
            transition_to(STATE_IDLE);
            break;
        default: break;
    }
}

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Inactivity Timeout

If no button is pressed for 30 seconds while in MENU or ALARM_SET, return to IDLE automatically:

static TimerHandle_t inactivity_timer = NULL;

static void inactivity_callback(TimerHandle_t t) {
    if (current_state == STATE_MENU || current_state == STATE_ALARM_SET) {
        transition_to(STATE_IDLE);
    }
}

// Reset the timer on every button event:
xTimerReset(inactivity_timer, 0);