launcher: first crack at low power 'screensaver' mode

apps/Sensor Watch Starter Project/app.c

@@ -157,7 +157,7 @@ bool app_loop() {
         delay_ms(250);
 
         // nap time :)
-        watch_enter_shallow_sleep(NULL);
+        watch_enter_shallow_sleep(false);
 
         // we just woke up; wait a moment again for the user's finger to be off the button...
         delay_ms(250);

launcher/launcher.c

@@ -1,19 +1,27 @@
 #include <stdio.h>
 #include <string.h>
+#include <limits.h>
 #include "watch.h"
 #include "launcher.h"
 #include "launcher_config.h"
 
 LauncherState launcher_state;
 void * widget_contexts[LAUNCHER_NUM_WIDGETS];
+const int32_t launcher_screensaver_deadlines[8] = {INT_MAX, 3600, 7200, 21600, 43200, 86400, 172800, 604800};
 
-void cb_mode_pressed();
+void cb_mode_btn_interrupt();
-void cb_light_pressed();
+void cb_light_btn_interrupt();
-void cb_alarm_pressed();
+void cb_alarm_btn_interrupt();
+void cb_alarm_btn_extwake();
+void cb_alarm_fired();
 void cb_tick();
 
+static inline void _launcher_reset_screensaver_countdown() {
+    // for testing, make the timeout happen 60x faster.
+    launcher_state.screensaver_ticks = launcher_screensaver_deadlines[launcher_state.launcher_settings.bit.screensaver_interval] / 60;
+}
+
 void launcher_request_tick_frequency(uint8_t freq) {
-    // FIXME: there is an issue where after changing tick frequencies on a widget switch, something glitchy happens on the next one.
     watch_rtc_disable_all_periodic_callbacks();
     launcher_state.subsecond = 0;
     launcher_state.tick_frequency = freq;
@@ -39,10 +47,11 @@ void launcher_move_to_next_widget() {
 
 void app_init() {
     memset(&launcher_state, 0, sizeof(launcher_state));
+
     launcher_state.launcher_settings.bit.led_green_color = 0xF;
     launcher_state.launcher_settings.bit.button_should_sound = true;
-    watch_date_time date_time = watch_rtc_get_date_time();
+    launcher_state.launcher_settings.bit.screensaver_interval = 1;
-    watch_rtc_set_date_time(date_time);
+    _launcher_reset_screensaver_countdown();
 }
 
 void app_wake_from_deep_sleep() {
@@ -50,10 +59,13 @@ void app_wake_from_deep_sleep() {
 }
 
 void app_setup() {
+    if (launcher_state.screensaver_ticks != -1) {
+        watch_disable_extwake_interrupt(BTN_ALARM);
+
         watch_enable_external_interrupts();
-    watch_register_interrupt_callback(BTN_MODE, cb_mode_pressed, INTERRUPT_TRIGGER_BOTH);
+        watch_register_interrupt_callback(BTN_MODE, cb_mode_btn_interrupt, INTERRUPT_TRIGGER_BOTH);
-    watch_register_interrupt_callback(BTN_LIGHT, cb_light_pressed, INTERRUPT_TRIGGER_BOTH);
+        watch_register_interrupt_callback(BTN_LIGHT, cb_light_btn_interrupt, INTERRUPT_TRIGGER_BOTH);
-    watch_register_interrupt_callback(BTN_ALARM, cb_alarm_pressed, INTERRUPT_TRIGGER_BOTH);
+        watch_register_interrupt_callback(BTN_ALARM, cb_alarm_btn_interrupt, INTERRUPT_TRIGGER_BOTH);
 
         watch_enable_buzzer();
         watch_enable_leds();
@@ -68,6 +80,7 @@ void app_setup() {
         widgets[0].activate(&launcher_state.launcher_settings, widget_contexts[launcher_state.current_widget]);
         widgets[0].loop(EVENT_ACTIVATE, &launcher_state.launcher_settings, 0, widget_contexts[launcher_state.current_widget]);
     }
+}
 
 void app_prepare_for_sleep() {
 }
@@ -106,6 +119,19 @@ bool app_loop() {
         }
     }
 
+    // if we have timed out of our screensaver countdown, enter screensaver mode.
+    if (launcher_state.screensaver_ticks == 0) {
+        launcher_state.screensaver_ticks = -1;
+        watch_date_time alarm_time;
+        alarm_time.reg = 0;
+        alarm_time.unit.second = 59; // after a match, the alarm fires at the next rising edge of CLK_RTC_CNT, so 59 seconds lets us update at :00
+        watch_rtc_register_alarm_callback(cb_alarm_fired, alarm_time, ALARM_MATCH_SS);
+        watch_register_extwake_callback(BTN_ALARM, cb_alarm_btn_extwake, true);
+        widgets[launcher_state.current_widget].loop(EVENT_SCREENSAVER, &launcher_state.launcher_settings, 0, widget_contexts[launcher_state.current_widget]);
+        event = EVENT_SCREENSAVER;
+        watch_enter_shallow_sleep(true);
+    }
+
     if (event) {
         widgets[launcher_state.current_widget].loop(event, &launcher_state.launcher_settings, launcher_state.subsecond, widget_contexts[launcher_state.current_widget]);
         event = 0;
@@ -130,23 +156,38 @@ LauncherEvent _figure_out_button_event(LauncherEvent button_down_event, uint8_t
     }
 }
 
-void cb_light_pressed() {
+void cb_light_btn_interrupt() {
+    _launcher_reset_screensaver_countdown();
     event = _figure_out_button_event(EVENT_LIGHT_BUTTON_DOWN, &launcher_state.light_down_timestamp);
 }
 
-void cb_mode_pressed() {
+void cb_mode_btn_interrupt() {
+    _launcher_reset_screensaver_countdown();
     event = _figure_out_button_event(EVENT_MODE_BUTTON_DOWN, &launcher_state.mode_down_timestamp);
 }
 
-void cb_alarm_pressed() {
+void cb_alarm_btn_interrupt() {
+    _launcher_reset_screensaver_countdown();
     event = _figure_out_button_event(EVENT_ALARM_BUTTON_DOWN, &launcher_state.alarm_down_timestamp);
 }
 
+void cb_alarm_btn_extwake() {
+    _launcher_reset_screensaver_countdown();
+    // this is a hack: waking from shallow sleep, app_setup does get called, but it happens before we reset our ticks.
+    // need to figure out if there's a better heuristic for determining how we woke up.
+    app_setup();
+}
+
+void cb_alarm_fired() {
+    event = EVENT_SCREENSAVER;
+}
+
 void cb_tick() {
     event = EVENT_TICK;
     watch_date_time date_time = watch_rtc_get_date_time();
     if (date_time.unit.second != launcher_state.last_second) {
         if (launcher_state.light_ticks) launcher_state.light_ticks--;
+        if (launcher_state.launcher_settings.bit.screensaver_interval && launcher_state.screensaver_ticks > 0) launcher_state.screensaver_ticks--;
 
         launcher_state.last_second = date_time.unit.second;
         launcher_state.subsecond = 0;

launcher/launcher.h

@@ -25,6 +25,7 @@ typedef enum LauncherEvent {
     EVENT_NONE = 0,             // There is no event to report.
     EVENT_ACTIVATE,             // Your widget is entering the foreground.
     EVENT_TICK,                 // Most common event type. Your widget is being called from the tick callback.
+    EVENT_SCREENSAVER,          // Your widget is being asked to display its output for screensaver mode.
     EVENT_LIGHT_BUTTON_DOWN,    // The light button has been pressed, but not yet released.
     EVENT_LIGHT_BUTTON_UP,      // The light button was pressed and released.
     EVENT_LIGHT_LONG_PRESS,     // The light button was held for >2 seconds, and released.
@@ -65,6 +66,9 @@ typedef struct LauncherState {
     uint8_t mode_down_timestamp;
     uint8_t alarm_down_timestamp;
 
+    // screensaver countdown
+    int32_t screensaver_ticks;
+
     // stuff for subsecond tracking
     uint8_t tick_frequency;
     uint8_t last_second;

launcher/widgets/clock/simple_clock_widget.c

@@ -27,17 +27,18 @@ void simple_clock_widget_loop(LauncherEvent event, LauncherSettings *settings, u
     watch_date_time date_time;
     uint32_t previous_date_time;
     switch (event) {
-        case EVENT_TICK:
         case EVENT_ACTIVATE:
+        case EVENT_TICK:
+        case EVENT_SCREENSAVER:
             date_time = watch_rtc_get_date_time();
             previous_date_time = *((uint32_t *)context);
             *((uint32_t *)context) = date_time.reg;
 
-            if (date_time.reg >> 6 == previous_date_time >> 6) {
+            if (date_time.reg >> 6 == previous_date_time >> 6 && event != EVENT_SCREENSAVER) {
                 // everything before seconds is the same, don't waste cycles setting those segments.
                 pos = 8;
                 sprintf(buf, "%02d", date_time.unit.second);
-            } else if (date_time.reg >> 12 == previous_date_time >> 12) {
+            } else if (date_time.reg >> 12 == previous_date_time >> 12 && event != EVENT_SCREENSAVER) {
                 // everything before minutes is the same.
                 pos = 6;
                 sprintf(buf, "%02d%02d", date_time.unit.minute, date_time.unit.second);
@@ -54,8 +55,12 @@ void simple_clock_widget_loop(LauncherEvent event, LauncherSettings *settings, u
                     if (date_time.unit.hour == 0) date_time.unit.hour = 12;
                 }
                 pos = 0;
+                if (event == EVENT_SCREENSAVER) {
+                    sprintf(buf, "%s%2d%2d%02d  ", weekdays[simple_clock_widget_get_weekday(date_time.unit.year, date_time.unit.month, date_time.unit.day)], date_time.unit.day, date_time.unit.hour, date_time.unit.minute);
+                } else {
                     sprintf(buf, "%s%2d%2d%02d%02d", weekdays[simple_clock_widget_get_weekday(date_time.unit.year, date_time.unit.month, date_time.unit.day)], date_time.unit.day, date_time.unit.hour, date_time.unit.minute, date_time.unit.second);
                 }
+            }
             watch_display_string(buf, pos);
             break;
         case EVENT_MODE_BUTTON_UP:

watch-library/watch/watch_deepsleep.c

@@ -151,11 +151,8 @@ void _watch_disable_all_peripherals_except_slcd() {
     MCLK->APBCMASK.reg &= ~MCLK_APBCMASK_SERCOM3;
 }
 
-void watch_enter_shallow_sleep(char *message) {
+void watch_enter_shallow_sleep(bool display_on) {
-    if (message != NULL) {
+    if (!display_on) {
-        watch_display_string("          ", 0);
-        watch_display_string(message, 0);
-    } else {
         slcd_sync_deinit(&SEGMENT_LCD_0);
         hri_mclk_clear_APBCMASK_SLCD_bit(SLCD);
     }

watch-library/watch/watch_deepsleep.h

@@ -81,13 +81,8 @@ uint32_t watch_get_backup_data(uint8_t reg);
   *        the LCD. You can wake from this mode by pressing the ALARM button, if you have an registered an
   *        external wake callback on the ALARM button. When your app wakes from this shallow sleep mode, your
   *        app_setup method will be called, since this function will have disabled things you set up.
-  * @param message Either NULL, or a string representing a message to display while in shallow sleep mode. If
+  * @param display_on if true, leaves the LCD on to display whatever content was on-screen. If false, disables
-  *                this parameter is NULL, the screen will be blanked out, and this function will disable the
+  *                   the segment LCD controller for additional power savings.
-  *                SLCD peripheral for additional power savings. If the message is non-NULL, it will replace
-  *                any text on the screen, and will be displayed at position 0 (so you should pad out the beginning
-  *                of the string with spaces if you wish for the message to appear on line 2, i.e. "    SLEEP").
-  *                Also note that this function will NOT clear any indicator segments that you have set. This is
-  *                by design, in case you wish to leave an indicator lit in sleep mode.
   * @details This shallow sleep mode is not the lowest power mode available (see watch_enter_deep_sleep), but
   *          it has the benefit of retaining your application state and being able to wake from the ALARM button.
   *          It also provides an option for displaying a message to the user when asleep. Note that whether you
@@ -96,10 +91,10 @@ uint32_t watch_get_backup_data(uint8_t reg);
   *
   *          Power consumption in shallow sleep mode varies a bit with the battery voltage and the temperature,
   *          but at 3 V and 25~30° C you can roughly estimate:
-  *           * < 12µA current draw with the LCD controller on (message != NULL)
+  *           * < 12µA current draw with the LCD controller on
-  *           * < 6µA current draw with the LCD controller off (message == NULL)
+  *           * < 6µA current draw with the LCD controller off
   */
-void watch_enter_shallow_sleep(char *message);
+void watch_enter_shallow_sleep(bool display_on);
 
 /** @brief Enters the SAM L22's lowest-power mode, BACKUP.
   * @details This function does some housekeeping before entering BACKUP mode. It first disables all