Enhance ShowBattery and fixes for Odroid-GO battery

Add a "Real-time values" checkbox to ShowBattery app. If checked, then the cache will be clear on
every cycle.

Bugfix: Use `mpos.time.localtime()` to get the "correct" local time with timezone offset.

Changes for Odroid-GO:

The seen "2400" values are at startup the Odroid-GO... After a while the values are somewhere
between 270 and 310... The full range is unknown, yet. But with the new calculation it looks more
realistic, then before ;)

internal_filesystem/apps/com.micropythonos.showbattery/META-INF/MANIFEST.JSON

@@ -6,7 +6,7 @@
 "icon_url": "https://apps.micropythonos.com/apps/com.micropythonos.showbattery/icons/com.micropythonos.showbattery_0.1.1_64x64.png",
 "download_url": "https://apps.micropythonos.com/apps/com.micropythonos.showbattery/mpks/com.micropythonos.showbattery_0.1.1.mpk",
 "fullname": "com.micropythonos.showbattery",
-"version": "0.1.1",
+"version": "0.2.0",
 "category": "development",
 "activities": [
     {

internal_filesystem/apps/com.micropythonos.showbattery/assets/show_battery.py

@@ -40,8 +40,7 @@ I want application that will show big time (hour, minutes), with smaller seconds
 """
 
 import lvgl as lv
-import time
-
+import mpos.time
 from mpos import Activity, BatteryManager
 
 HISTORY_LEN = 60
@@ -56,11 +55,13 @@ class ShowBattery(Activity):
     # Widgets
     lbl_time = None
     lbl_sec = None
-    lbl_date = None
+    lbl_text = None
 
     bat_outline = None
     bat_fill = None
 
+    clear_cache_checkbox = None  # Add reference to checkbox
+
     history_v = []
     history_p = []
 
@@ -69,16 +70,21 @@ class ShowBattery(Activity):
 
         # --- TIME ---
         self.lbl_time = lv.label(scr)
-        self.lbl_time.set_style_text_font(lv.font_montserrat_48, 0)
+        self.lbl_time.set_style_text_font(lv.font_montserrat_40, 0)
         self.lbl_time.align(lv.ALIGN.TOP_LEFT, 5, 5)
 
         self.lbl_sec = lv.label(scr)
         self.lbl_sec.set_style_text_font(lv.font_montserrat_24, 0)
         self.lbl_sec.align_to(self.lbl_time, lv.ALIGN.OUT_RIGHT_BOTTOM, 24, -4)
 
-        self.lbl_date = lv.label(scr)
-        self.lbl_date.set_style_text_font(lv.font_montserrat_24, 0)
-        self.lbl_date.align(lv.ALIGN.TOP_LEFT, 5, 60)
+        # --- CHECKBOX ---
+        self.clear_cache_checkbox = lv.checkbox(scr)
+        self.clear_cache_checkbox.set_text("Real-time values")
+        self.clear_cache_checkbox.align(lv.ALIGN.TOP_LEFT, 5, 50)
+
+        self.lbl_text = lv.label(scr)
+        self.lbl_text.set_style_text_font(lv.font_montserrat_16, 0)
+        self.lbl_text.align(lv.ALIGN.TOP_LEFT, 5, 80)
 
         # --- BATTERY ICON ---
         self.bat_outline = lv.obj(scr)
@@ -126,19 +132,26 @@ class ShowBattery(Activity):
         super().onResume(screen)
 
         def update(timer):
-            now = time.localtime()
+            now = mpos.time.localtime()
 
             hour, minute, second = now[3], now[4], now[5]
             date = f"{now[0]}-{now[1]:02}-{now[2]:02}"
 
+            if self.clear_cache_checkbox.get_state() & lv.STATE.CHECKED:
+                # Get "real-time" values by clearing the cache before reading
+                BatteryManager.clear_cache()
+
             voltage = BatteryManager.read_battery_voltage()
             percent = BatteryManager.get_battery_percentage()
 
             # --- TIME ---
             self.lbl_time.set_text(f"{hour:02}:{minute:02}")
             self.lbl_sec.set_text(f":{second:02}")
+
+            # --- BATTERY VALUES ---
             date += f"\n{voltage:.2f}V {percent:.0f}%"
-            self.lbl_date.set_text(date)
+            date += f"\nRaw ADC: {BatteryManager.read_raw_adc()}"
+            self.lbl_text.set_text(date)
 
             # --- BATTERY ICON ---
             fill_h = int((percent / 100) * (self.bat_size * 0.9))

internal_filesystem/lib/mpos/board/odroid_go.py

@@ -48,7 +48,6 @@ CROSSBAR_Y = const(35)
 # Misc settings:
 LED_BLUE = const(2)
 BATTERY_PIN = const(36)
-BATTERY_RESISTANCE_NUM = const(2)
 SPEAKER_ENABLE_PIN = const(25)
 SPEAKER_PIN = const(26)
 
@@ -105,8 +104,22 @@ print("odroid_go.py Battery initialization...")
 from mpos import BatteryManager
 
 
-def adc_to_voltage(adc_value):
-    return adc_value * BATTERY_RESISTANCE_NUM
+def adc_to_voltage(raw_adc_value):
+    """
+    The percentage calculation uses MIN_VOLTAGE = 3.15 and MAX_VOLTAGE = 4.15
+    0% at 3.15V -> raw_adc_value = 270
+    100% at 4.15V -> raw_adc_value = 310
+
+    4.15 - 3.15 = 1V
+    310 - 270 = 40 raw ADC steps
+
+    So each raw ADC step is 1V / 40 = 0.025V
+    Offset calculation:
+    270 * 0.025 = 6.75V. but we want it to be 3.15V
+    So the offset is 3.15V - 6.75V = -3.6V
+    """
+    voltage = raw_adc_value * 0.025 - 3.6
+    return voltage
 
 
 BatteryManager.init_adc(BATTERY_PIN, adc_to_voltage)
@@ -183,6 +196,7 @@ def input_callback(indev, data):
         current_key = lv.KEY.ESC
     elif button_volume.value() == 0:
         print("Volume button pressed -> reset")
+        blue_led.on()
         machine.reset()
     elif button_select.value() == 0:
         current_key = lv.KEY.BACKSPACE