Fix: green LED flicker between red mute flashes during a DMR QSO

The DMR RX handler re-asserts the green LED whenever it reads it off, racing the
main-loop mute clear, so green flickered between the red flashes. Add a
LedGreenSuppress() hold in the LED driver: while muted the green LED is forced
off (the re-assert becomes a no-op); on un-mute the hold is released and green is
restored from the current RX state.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,10 @@ single running list until the first versioned release.
 
 ## Unreleased
 
+- **Fix:** green LED **flickering** between the red flashes while muted during a DMR
+  QSO. The DMR RX handler re-asserts the green LED as soon as it reads it off, racing
+  the main-loop mute clear; the green LED is now **held off at the driver** for the
+  whole mute (and released on un-mute), so only the red flash shows.
 - **`screenshot.sh`** — a one-command wrapper around the OpenGD77 screen grabber
   that auto-detects the serial port and sets up a self-contained Python venv
   (pyserial + pillow) on first run. Saves to `screenshots/`.

MDUV380_firmware/application/source/applicationMain.c

@@ -1441,18 +1441,27 @@ void applicationMainTask(void)
 
 			if (audioAmpIsMuted() || (lastVolume == -99)) // explicit mute or volume knob fully down
 			{
+				if (!muteFlashActive)
+				{
+					// Hold the green LED off for the whole mute, so the DMR RX handler
+					// (which re-asserts green as soon as it reads it off) can't make it
+					// flicker green between the red flashes.
+					LedGreenSuppress(true);
+					muteFlashActive = true;
+				}
+
 				bool flashOn = ((ticksGetMillis() % 2000) < 500);
-				LedWrite(LED_GREEN, 0);
 				LedWrite(LED_RED, (flashOn ? 1 : 0));
-				muteFlashActive = true;
 			}
 			else if (muteFlashActive)
 			{
-				// Just unmuted: stop the red flash and restore the green LED to the
+				// Just unmuted: release the green hold, stop the red flash and restore
-				// current RX state, so a QSO in progress lights green again instead of
+				// the green LED to the current RX state, so a QSO in progress lights
-				// staying dark. Green is normally lit for an active DMR slot (matching
+				// green again instead of staying dark. Green is normally lit for an
-				// our filter) or a received FM/digital signal; if nothing is being
+				// active DMR slot (matching our filter) or a received FM/digital signal;
-				// received it stays off. The normal RX code then keeps it correct.
+				// if nothing is being received it stays off. The normal RX code then
+				// keeps it correct.
+				LedGreenSuppress(false);
 				bool rxGreen = (slotState == DMR_STATE_RX_1) || (slotState == DMR_STATE_RX_2) ||
 						currentRadioDevice->analogSignalReceived || currentRadioDevice->digitalSignalReceived;
 				LedWrite(LED_RED, 0);

MDUV380_firmware/application/source/io/Leds.c

@@ -48,9 +48,28 @@ void LEDsInit(void)
 #endif
 }
 
+// When set, the green LED is held off: any LedWrite(LED_GREEN, 1) is forced to 0.
+// Used while muted so the DMR RX handler (which re-asserts green whenever it reads
+// it as 0) can't make the green LED flicker between the red mute flashes.
+static volatile bool greenLedSuppressed = false;
+
+void LedGreenSuppress(bool suppress)
+{
+	greenLedSuppressed = suppress;
+	if (suppress)
+	{
+		LedWrite(LED_GREEN, 0); // force it off now
+	}
+}
+
 void LedWrite(LEDs_t theLED, uint8_t output)
 {
 #if ! defined(PLATFORM_GD77S)
+	if ((theLED == LED_GREEN) && greenLedSuppressed)
+	{
+		output = 0; // green is held off (e.g. while muted)
+	}
+
 	LEDsState[theLED] = output;
 
 	if (settingsIsOptionBitSet(BIT_ALL_LEDS_DISABLED) == 0)