Battery header: add "Bars" display mode

Extends the battery header setting from a %/V toggle into a 3-state
option (Percentage / Voltage / Bars), encoded across two option bits so
existing codeplugs keep reading as Percentage.

Bars renders a battery-shaped icon (outlined body + terminal nub) with
up to 4 segments, each representing 25% of charge, and blinks the fill
when the battery is low.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

MDUV380_firmware/application/include/functions/settings.h

@@ -129,7 +129,7 @@ typedef enum
 {
 	BIT_INVERSE_VIDEO               = (SETTINGS_BITS_BANK_0 | (1 << 0)),
 	BIT_PTT_LATCH                   = (SETTINGS_BITS_BANK_0 | (1 << 1)),
-	BIT_UNUSED_2                    = (SETTINGS_BITS_BANK_0 | (1 << 2)),
+	BIT_BATTERY_BARS_IN_HEADER      = (SETTINGS_BITS_BANK_0 | (1 << 2)), // companion to BIT_BATTERY_VOLTAGE_IN_HEADER: encodes the "Bars" battery display mode
 	BIT_BATTERY_VOLTAGE_IN_HEADER   = (SETTINGS_BITS_BANK_0 | (1 << 3)),
 	BIT_SETTINGS_UPDATED            = (SETTINGS_BITS_BANK_0 | (1 << 4)),
 	BIT_TX_RX_FREQ_LOCK             = (SETTINGS_BITS_BANK_0 | (1 << 5)),
@@ -411,6 +411,20 @@ void settingsSetOptionBit(bitfieldOptions_t bit, bool set);
 bool settingsIsOptionBitSetFromSettings(settingsStruct_t *sets, bitfieldOptions_t bit);
 bool settingsIsOptionBitSet(bitfieldOptions_t bit);
 
+// How the battery level is shown in the header. Encoded across two option bits
+// (BIT_BATTERY_VOLTAGE_IN_HEADER / BIT_BATTERY_BARS_IN_HEADER) for backwards
+// compatibility: an unset pair reads as PERCENTAGE, matching legacy behaviour.
+typedef enum
+{
+	BATTERY_UNIT_PERCENTAGE = 0,
+	BATTERY_UNIT_VOLTAGE,
+	BATTERY_UNIT_BARS,
+	NUM_BATTERY_UNIT_DISPLAY
+} batteryUnitDisplay_t;
+
+batteryUnitDisplay_t settingsGetBatteryUnitDisplay(void);
+void settingsSetBatteryUnitDisplay(batteryUnitDisplay_t mode);
+
 void settingsSetDirty(void);
 void settingsSetVFODirty(void);
 void settingsSaveIfNeeded(bool immediately);

MDUV380_firmware/application/source/functions/settings.c

@@ -619,6 +619,27 @@ void settingsSetScreenDimLevel(uint8_t level)
 	settingsSetOptionBit(BIT_SCREEN_DIM_2, ((level & 4) != 0));
 }
 
+// Battery header display mode is stored across two option bits so existing
+// codeplugs (both bits clear) keep reading as BATTERY_UNIT_PERCENTAGE.
+batteryUnitDisplay_t settingsGetBatteryUnitDisplay(void)
+{
+	if (settingsIsOptionBitSet(BIT_BATTERY_BARS_IN_HEADER))
+	{
+		return BATTERY_UNIT_BARS;
+	}
+	if (settingsIsOptionBitSet(BIT_BATTERY_VOLTAGE_IN_HEADER))
+	{
+		return BATTERY_UNIT_VOLTAGE;
+	}
+	return BATTERY_UNIT_PERCENTAGE;
+}
+
+void settingsSetBatteryUnitDisplay(batteryUnitDisplay_t mode)
+{
+	settingsSetOptionBit(BIT_BATTERY_VOLTAGE_IN_HEADER, (mode == BATTERY_UNIT_VOLTAGE));
+	settingsSetOptionBit(BIT_BATTERY_BARS_IN_HEADER, (mode == BATTERY_UNIT_BARS));
+}
+
 void settingsSetDirty(void)
 {
 	settingsDirty = true;

MDUV380_firmware/application/source/user_interface/menuDisplayOptions.c

@@ -314,15 +314,20 @@ static void updateScreen(bool isFirstRun)
 #if ! defined(PLATFORM_MD9600)
 				case DISPLAY_BATTERY_UNIT_IN_HEADER:
 					leftSide = currentLanguage->battery;
-					if (settingsIsOptionBitSet(BIT_BATTERY_VOLTAGE_IN_HEADER))
+					switch (settingsGetBatteryUnitDisplay())
 					{
-						rightSideUnitsPrompt = PROMPT_VOLTS;
+						case BATTERY_UNIT_VOLTAGE:
-						rightSideUnitsStr = "V";
+							rightSideUnitsPrompt = PROMPT_VOLTS;
-					}
+							rightSideUnitsStr = "V";
-					else
+							break;
-					{
+						case BATTERY_UNIT_BARS:
-						rightSideUnitsPrompt = PROMPT_PERCENT;
+							// Plain literal -> rightSideVar (voice-safe), like the Screen Dim entry above.
-						rightSideUnitsStr = "%";
+							snprintf(rightSideVar, SCREEN_LINE_BUFFER_SIZE, "%s", "Bars");
+							break;
+						default: // BATTERY_UNIT_PERCENTAGE
+							rightSideUnitsPrompt = PROMPT_PERCENT;
+							rightSideUnitsStr = "%";
+							break;
 					}
 					break;
 #endif
@@ -705,9 +710,12 @@ static void handleEvent(uiEvent_t *ev)
 
 #if ! defined(PLATFORM_MD9600)
 				case DISPLAY_BATTERY_UNIT_IN_HEADER:
-					if (settingsIsOptionBitSet(BIT_BATTERY_VOLTAGE_IN_HEADER) == false)
 					{
-						settingsSetOptionBit(BIT_BATTERY_VOLTAGE_IN_HEADER, true);
+						batteryUnitDisplay_t batteryUnit = settingsGetBatteryUnitDisplay();
+						if (batteryUnit < (NUM_BATTERY_UNIT_DISPLAY - 1))
+						{
+							settingsSetBatteryUnitDisplay(batteryUnit + 1);
+						}
 					}
 					break;
 #endif
@@ -928,9 +936,12 @@ static void handleEvent(uiEvent_t *ev)
 
 #if ! defined(PLATFORM_MD9600)
 				case DISPLAY_BATTERY_UNIT_IN_HEADER:
-					if (settingsIsOptionBitSet(BIT_BATTERY_VOLTAGE_IN_HEADER))
 					{
-						settingsSetOptionBit(BIT_BATTERY_VOLTAGE_IN_HEADER, false);
+						batteryUnitDisplay_t batteryUnit = settingsGetBatteryUnitDisplay();
+						if (batteryUnit > BATTERY_UNIT_PERCENTAGE)
+						{
+							settingsSetBatteryUnitDisplay(batteryUnit - 1);
+						}
 					}
 					break;
 #endif
@@ -1182,6 +1193,7 @@ static void exitCallback(void *data)
 #endif
 #if ! defined(PLATFORM_MD9600)
 				BIT_BATTERY_VOLTAGE_IN_HEADER,
+				BIT_BATTERY_BARS_IN_HEADER,
 #endif
 #if defined(HAS_SOFT_VOLUME)
 				BIT_VISUAL_VOLUME,

MDUV380_firmware/application/source/user_interface/uiUtilities.c

@@ -1897,7 +1897,7 @@ void uiUtilityRenderHeader(bool isVFODualWatchScanning, bool isVFOSweepScanning,
 	UNUSED_PARAMETER(forceBatteryDisplay);
 #endif
 
-	if (settingsIsOptionBitSet(BIT_BATTERY_VOLTAGE_IN_HEADER))
+	if (settingsGetBatteryUnitDisplay() == BATTERY_UNIT_VOLTAGE)
 	{
 		getBatteryVoltage(&volts, &mvolts);
 
@@ -1911,6 +1911,7 @@ void uiUtilityRenderHeader(bool isVFODualWatchScanning, bool isVFOSweepScanning,
 	}
 	else
 	{
+		// Both the percentage and bars display modes need the battery percentage.
 		batteryPercentage = getBatteryPercentage();
 
 		if (batteryPercentage < 100)
@@ -2207,7 +2208,9 @@ void uiUtilityRenderHeader(bool isVFODualWatchScanning, bool isVFOSweepScanning,
 	else
 #endif
 	{
-		if (settingsIsOptionBitSet(BIT_BATTERY_VOLTAGE_IN_HEADER))
+		batteryUnitDisplay_t batteryUnit = settingsGetBatteryUnitDisplay();
+
+		if (batteryUnit == BATTERY_UNIT_VOLTAGE)
 		{
 			int16_t xV = (DISPLAY_SIZE_X - ((4 * 6) + 3));
 
@@ -2219,6 +2222,41 @@ void uiUtilityRenderHeader(bool isVFODualWatchScanning, bool isVFOSweepScanning,
 			snprintf(buffer, SCREEN_LINE_BUFFER_SIZE, "%1dV", mvolts);
 			displayPrintCore(xV + (6 * 2) + 3, DISPLAY_Y_POS_HEADER, buffer, (apoEnabled ? FONT_SIZE_1_BOLD : FONT_SIZE_1), TEXT_ALIGN_LEFT, ((batteryIsLow ? scanBlinkPhase : false)));
 		}
+		else if (batteryUnit == BATTERY_UNIT_BARS)
+		{
+			// Battery-shaped icon, right-aligned in the header: an outlined body with a
+			// terminal nub, holding up to 4 segments each representing 25% of charge.
+			const int16_t bodyW = 24;
+			const int16_t bodyH = 7;
+			const int16_t nubW = 2;
+			const int16_t nubH = 3;
+			const int16_t barW = 4;
+			const int16_t barGap = 1;
+			int16_t bx = (DISPLAY_SIZE_X - bodyW - nubW);
+			int16_t by = DISPLAY_Y_POS_HEADER;
+
+			// 0..4 filled segments (rounded to the nearest quarter).
+			int16_t filledBars = ((batteryPercentage + 12) / 25);
+			if (filledBars > 4)
+			{
+				filledBars = 4;
+			}
+			else if (filledBars < 0)
+			{
+				filledBars = 0;
+			}
+
+			// Body outline and terminal nub stay solid; only the fill blinks when low.
+			// NOTE: displayDrawRect uses isInverted==true for foreground (visible), whereas
+			// displayFillRect is the opposite (isInverted==false draws the foreground).
+			displayDrawRect(bx, by, bodyW, bodyH, true);
+			displayFillRect(bx + bodyW, by + ((bodyH - nubH) / 2), nubW, nubH, false);
+
+			for (int16_t b = 0; b < filledBars; b++)
+			{
+				displayFillRect(bx + 2 + (b * (barW + barGap)), by + 2, barW, (bodyH - 4), ((batteryIsLow ? scanBlinkPhase : false)));
+			}
+		}
 		else
 		{
 			snprintf(buffer, SCREEN_LINE_BUFFER_SIZE, "%d%%", batteryPercentage);
@@ -3149,12 +3187,13 @@ void announceItemWithInit(bool init, voicePromptItem_t item, audioPromptThreshol
 			break;
 
 		case PROMPT_SEQUENCE_BATTERY:
-			if (settingsIsOptionBitSet(BIT_BATTERY_VOLTAGE_IN_HEADER))
+			if (settingsGetBatteryUnitDisplay() == BATTERY_UNIT_VOLTAGE)
 			{
 				announceBatteryVoltage();
 			}
 			else
 			{
+				// Bars mode maps to a charge percentage, so announce it as a percentage.
 				announceBatteryPercentage();
 			}
 			break;