indicate battery voltage on display

vibrating_alarm_m5stickc.py

@@ -41,6 +41,7 @@ class App:
         self._alarm_hour_text_box = None
         self._alarm_minute_text_box = None
         self._alarm_timer = None
+        self._battery_status_text_box = None
 
     @property
     def _now_time(self) -> int:
@@ -189,17 +190,33 @@ class App:
         self._alarm_timer = machine.Timer(2)
         self._configure_alarm_timer()
 
+    def _update_battery_status_info(self) -> None:
+        self._battery_status_text_box.setText(  # type: ignore
+            "{:.02f}V".format(axp.getBatVoltage())
+        )
+
+    def _setup_battery_status_info(self) -> None:
+        self._battery_status_text_box = m5ui.M5TextBox(
+            12,
+            _SCREEN_HEIGHT - 20,
+            "",
+            lcd.FONT_DejaVu18,
+            _DEFAULT_FONT_COLOR,
+            rotate=0,
+        )
+
     def run(self) -> None:
         m5ui.setScreenColor(0x000000)  # clear screen
-        print("battery:", axp.getBatVoltage(), "V")
         self._setup_clock()
         self._setup_alarm()
+        self._setup_battery_status_info()
         btnA.wasPressed(self._button_a_pressed)
         btnB.wasPressed(self._button_b_pressed)
         # not sure whether ext0 would be better
         esp32.wake_on_ext1([btnA.pin], esp32.WAKEUP_ALL_LOW)
         self._reschedule_sleep(interrupt=False)
         while True:
+            self._update_battery_status_info()
             while utime.time() < self._sleep_start_time_seconds:
                 utime.sleep(1)  # seconds
             # TODO turn off display