diff --git a/app/action.c b/app/action.c
index e980b91..ff6ba58 100644
--- a/app/action.c
+++ b/app/action.c
@@ -230,7 +230,7 @@ void ACTION_Handle(KEY_Code_t Key, bool bKeyPressed, bool bKeyHeld)
 				gDTMF_InputBox[--gDTMF_InputIndex] = '-';
 				if (gDTMF_InputIndex)
 				{
-					gPttWasReleased = true;
+					gPttWasReleased       = true;
 					gRequestDisplayScreen = DISPLAY_MAIN;
 					return;
 				}
diff --git a/app/app.c b/app/app.c
index ae079dc..99b68db 100644
--- a/app/app.c
+++ b/app/app.c
@@ -907,6 +907,8 @@ void APP_Update(void)
 
 void APP_CheckKeys(void)
 {
+	const uint16_t key_repeat_delay = 70;   // 700ms
+	
 	KEY_Code_t Key;
 
 	#ifndef DISABLE_AIRCOPY
@@ -920,15 +922,25 @@ void APP_CheckKeys(void)
 	if (gPttIsPressed)
 	{
 		if (GPIO_CheckBit(&GPIOC->DATA, GPIOC_PIN_PTT))
-		{
-			SYSTEM_DelayMs(20);
+		{	// PTT released
 
-			if (GPIO_CheckBit(&GPIOC->DATA, GPIOC_PIN_PTT))
+			// denoise the PTT
+			unsigned int i     = 4;   // loop for 4ms
+			unsigned int count = 0;
+			while (i-- > 0)
+			{
+				SYSTEM_DelayMs(1);
+				if (GPIO_CheckBit(&GPIOC->DATA, GPIOC_PIN_PTT))
+					count++;
+				else
+				if (count > 0)
+					count--;
+			}
+
+			if (count >= 2)
 			{
 				APP_ProcessKey(KEY_PTT, false, false);
-
 				gPttIsPressed = false;
-
 				if (gKeyReading1 != KEY_INVALID)
 					gPttWasReleased = true;
 			}
@@ -938,7 +950,7 @@ void APP_CheckKeys(void)
 	{
 		if (!GPIO_CheckBit(&GPIOC->DATA, GPIOC_PIN_PTT))
 		{
-			if (++gPttDebounceCounter > 4)
+			if (++gPttDebounceCounter >= 4)	// 40ms
 			{
 				gPttIsPressed = true;
 				APP_ProcessKey(KEY_PTT, true, false);
@@ -982,7 +994,7 @@ void APP_CheckKeys(void)
 		gKeyBeingHeld = false;
 	}
 	else
-	if (gDebounceCounter == 128)
+	if (gDebounceCounter == key_repeat_delay)
 	{
 		if (Key == KEY_STAR || Key == KEY_F || Key == KEY_SIDE2 || Key == KEY_SIDE1 || Key == KEY_UP || Key == KEY_DOWN)
 		{
@@ -991,7 +1003,7 @@ void APP_CheckKeys(void)
 		}
 	}
 	else
-	if (gDebounceCounter > 128)
+	if (gDebounceCounter > key_repeat_delay)
 	{
 		if (Key == KEY_UP || Key == KEY_DOWN)
 		{
@@ -1003,14 +1015,14 @@ void APP_CheckKeys(void)
 		if (gDebounceCounter < 0xFFFF)
 			return;
 
-		gDebounceCounter = 128;
+		gDebounceCounter = key_repeat_delay;
 	}
 }
 
 void APP_TimeSlice10ms(void)
 {
 	gFlashLightBlinkCounter++;
-
+	
 	if (UART_IsCommandAvailable())
 	{
 		__disable_irq();
@@ -1102,6 +1114,7 @@ void APP_TimeSlice10ms(void)
 			}
 		#endif
 		
+		// repeater tail tone elimination
 		if (gRTTECountdown)
 		{
 			if (--gRTTECountdown == 0)
@@ -1560,9 +1573,7 @@ static void APP_ProcessKey(KEY_Code_t Key, bool bKeyPressed, bool bKeyHeld)
 		if (gDTMF_DecodeRing)
 		{
 			gDTMF_DecodeRing = false;
-
 			AUDIO_PlayBeep(BEEP_1KHZ_60MS_OPTIONAL);
-
 			if (Key != KEY_PTT)
 			{
 				gPttWasReleased = true;
diff --git a/dcs.h b/dcs.h
index 08db2bf..b8dfdc0 100644
--- a/dcs.h
+++ b/dcs.h
@@ -19,11 +19,12 @@
 
 #include <stdint.h>
 
-enum DCS_CodeType_t {
-	CODE_TYPE_OFF = 0x00U,
-	CODE_TYPE_CONTINUOUS_TONE = 0x01U,
-	CODE_TYPE_DIGITAL = 0x02U,
-	CODE_TYPE_REVERSE_DIGITAL = 0x03U,
+enum DCS_CodeType_t
+{
+	CODE_TYPE_OFF = 0,
+	CODE_TYPE_CONTINUOUS_TONE,
+	CODE_TYPE_DIGITAL,
+	CODE_TYPE_REVERSE_DIGITAL
 };
 
 typedef enum DCS_CodeType_t DCS_CodeType_t;
diff --git a/driver/backlight.c b/driver/backlight.c
index c50c77d..0ac2a0a 100644
--- a/driver/backlight.c
+++ b/driver/backlight.c
@@ -19,19 +19,14 @@
 #include "driver/gpio.h"
 #include "settings.h"
 
-uint8_t gBacklightCountdown;
+uint8_t gBacklightCountdown = 0;
 
 void BACKLIGHT_TurnOn(void)
 {
 	if (gEeprom.BACKLIGHT > 0)
 	{
-		GPIO_SetBit(&GPIOB->DATA, GPIOB_PIN_BACKLIGHT);
-		#if 0
-			gBacklightCountdown = 1 + (gEeprom.BACKLIGHT * 2);
-		#else
-			// much longer backlight times
-			gBacklightCountdown = (gEeprom.BACKLIGHT * 20) - 19;
-		#endif
+		GPIO_SetBit(&GPIOB->DATA, GPIOB_PIN_BACKLIGHT);  // turn the backlight ON
+		gBacklightCountdown = (gEeprom.BACKLIGHT < 5) ? (gEeprom.BACKLIGHT * 20) - 19 : 0;		// much longer backlight times
 	}
 }
 
diff --git a/firmware b/firmware
index 92a7bab..ec0749c 100644
Binary files a/firmware and b/firmware differ
diff --git a/firmware.bin b/firmware.bin
index 4e9d0a4..02a3cff 100644
Binary files a/firmware.bin and b/firmware.bin differ
diff --git a/firmware.packed.bin b/firmware.packed.bin
index 70c634a..7c0eb3d 100644
Binary files a/firmware.packed.bin and b/firmware.packed.bin differ
diff --git a/functions.h b/functions.h
index 1cc836f..991d921 100644
--- a/functions.h
+++ b/functions.h
@@ -19,18 +19,19 @@
 
 #include <stdint.h>
 
-enum FUNCTION_Type_t {
-	FUNCTION_FOREGROUND = 0U,
-	FUNCTION_TRANSMIT   = 1U,
-	FUNCTION_MONITOR    = 2U,
-	FUNCTION_INCOMING   = 3U,
-	FUNCTION_RECEIVE    = 4U,
-	FUNCTION_POWER_SAVE = 5U,
+enum FUNCTION_Type_t
+{
+	FUNCTION_FOREGROUND = 0,
+	FUNCTION_TRANSMIT,
+	FUNCTION_MONITOR,
+	FUNCTION_INCOMING,
+	FUNCTION_RECEIVE,
+	FUNCTION_POWER_SAVE
 };
 
 typedef enum FUNCTION_Type_t FUNCTION_Type_t;
 
-extern FUNCTION_Type_t gCurrentFunction;
+extern FUNCTION_Type_t       gCurrentFunction;
 
 void FUNCTION_Init(void);
 void FUNCTION_Select(FUNCTION_Type_t Function);
diff --git a/main.c b/main.c
index 910f66f..9dffc76 100644
--- a/main.c
+++ b/main.c
@@ -64,7 +64,6 @@ void Main(void)
 
 	SYSTICK_Init();
 	BOARD_Init();
-
 	UART_Init();
 	
 	#ifdef GIT_HASH
@@ -110,8 +109,12 @@ void Main(void)
 	if (!gChargingWithTypeC && !gBatteryDisplayLevel)
 	{
 		FUNCTION_Select(FUNCTION_POWER_SAVE);
-		//if (gEeprom.BACKLIGHT < 5)
-			GPIO_ClearBit(&GPIOB->DATA, GPIOB_PIN_BACKLIGHT);
+
+		if (gEeprom.BACKLIGHT < 5)
+			GPIO_ClearBit(&GPIOB->DATA, GPIOB_PIN_BACKLIGHT);	// turn the backlight OFF
+		else
+			GPIO_SetBit(&GPIOB->DATA, GPIOB_PIN_BACKLIGHT);  	// turn the backlight ON
+
 		gReducedService = true;
 	}
 	else
diff --git a/radio.c b/radio.c
index ec0e34a..5bdb0b8 100644
--- a/radio.c
+++ b/radio.c
@@ -874,17 +874,20 @@ void RADIO_EnableCxCSS(void)
 {
 	switch (gCurrentVfo->pTX->CodeType)
 	{
+		case CODE_TYPE_OFF:
+			break;
+			
+		case CODE_TYPE_CONTINUOUS_TONE:
+			BK4819_EnableCTCSS();
+			SYSTEM_DelayMs(200);
+			break;
+			
 		case CODE_TYPE_DIGITAL:
 		case CODE_TYPE_REVERSE_DIGITAL:
 			BK4819_EnableCDCSS();
-			break;
-
-		default:
-			BK4819_EnableCTCSS();
+			SYSTEM_DelayMs(200);
 			break;
 	}
-
-	SYSTEM_DelayMs(200);
 }
 
 void RADIO_PrepareCssTX(void)
diff --git a/scheduler.c b/scheduler.c
index be11dd0..089e65b 100644
--- a/scheduler.c
+++ b/scheduler.c
@@ -22,6 +22,10 @@
 #include "misc.h"
 #include "settings.h"
 
+#include "driver/backlight.h"
+#include "bsp/dp32g030/gpio.h"
+#include "driver/gpio.h"
+
 #define DECREMENT_AND_TRIGGER(cnt, flag) \
 	do { \
 		if (cnt) { \
@@ -35,40 +39,41 @@ static volatile uint32_t gGlobalSysTickCounter;
 
 void SystickHandler(void);
 
+// we come here every 10ms
 void SystickHandler(void)
 {
 	gGlobalSysTickCounter++;
+
 	gNextTimeslice = true;
-	if ((gGlobalSysTickCounter % 50) == 0) {
+
+	if ((gGlobalSysTickCounter % 50) == 0)
+	{
 		gNextTimeslice500ms = true;
 		DECREMENT_AND_TRIGGER(gTxTimerCountdown, gTxTimeoutReached);
 	}
-	if ((gGlobalSysTickCounter & 3) == 0) {
-		gNextTimeslice40ms = true;
-	}
-	if (gSystickCountdown2) {
-		gSystickCountdown2--;
-	}
-	if (gFoundCDCSSCountdown) {
-		gFoundCDCSSCountdown--;
-	}
-	if (gFoundCTCSSCountdown) {
-		gFoundCTCSSCountdown--;
-	}
-	if (gCurrentFunction == FUNCTION_FOREGROUND) {
-		DECREMENT_AND_TRIGGER(gBatterySaveCountdown, gSchedulePowerSave);
-	}
-	if (gCurrentFunction == FUNCTION_POWER_SAVE) {
-		DECREMENT_AND_TRIGGER(gBatterySave, gBatterySaveCountdownExpired);
-	}
 
-	if (gScanState == SCAN_OFF && gCssScanMode == CSS_SCAN_MODE_OFF && gEeprom.DUAL_WATCH != DUAL_WATCH_OFF) {
-		if (gCurrentFunction != FUNCTION_MONITOR && gCurrentFunction != FUNCTION_TRANSMIT) {
-			if (gCurrentFunction != FUNCTION_RECEIVE) {
+	if ((gGlobalSysTickCounter & 3) == 0)
+		gNextTimeslice40ms = true;
+
+	if (gSystickCountdown2)
+		gSystickCountdown2--;
+
+	if (gFoundCDCSSCountdown)
+		gFoundCDCSSCountdown--;
+
+	if (gFoundCTCSSCountdown)
+		gFoundCTCSSCountdown--;
+
+	if (gCurrentFunction == FUNCTION_FOREGROUND)
+		DECREMENT_AND_TRIGGER(gBatterySaveCountdown, gSchedulePowerSave);
+
+	if (gCurrentFunction == FUNCTION_POWER_SAVE)
+		DECREMENT_AND_TRIGGER(gBatterySave, gBatterySaveCountdownExpired);
+
+	if (gScanState == SCAN_OFF && gCssScanMode == CSS_SCAN_MODE_OFF && gEeprom.DUAL_WATCH != DUAL_WATCH_OFF)
+		if (gCurrentFunction != FUNCTION_MONITOR && gCurrentFunction != FUNCTION_TRANSMIT)
+			if (gCurrentFunction != FUNCTION_RECEIVE)
 				DECREMENT_AND_TRIGGER(gDualWatchCountdown, gScheduleDualWatch);
-			}
-		}
-	}
 
 	#ifndef DISABLE_NOAA
 		if (gScanState == SCAN_OFF && gCssScanMode == CSS_SCAN_MODE_OFF && gEeprom.DUAL_WATCH == DUAL_WATCH_OFF)
@@ -77,11 +82,9 @@ void SystickHandler(void)
 					DECREMENT_AND_TRIGGER(gNOAA_Countdown, gScheduleNOAA);
 	#endif
 
-	if (gScanState != SCAN_OFF || gCssScanMode == CSS_SCAN_MODE_SCANNING) {
-		if (gCurrentFunction != FUNCTION_MONITOR && gCurrentFunction != FUNCTION_TRANSMIT) {
+	if (gScanState != SCAN_OFF || gCssScanMode == CSS_SCAN_MODE_SCANNING)
+		if (gCurrentFunction != FUNCTION_MONITOR && gCurrentFunction != FUNCTION_TRANSMIT)
 			DECREMENT_AND_TRIGGER(ScanPauseDelayIn10msec, gScheduleScanListen);
-		}
-	}
 
 	DECREMENT_AND_TRIGGER(gTailNoteEliminationCountdown, gFlagTteComplete);
 
@@ -89,13 +92,28 @@ void SystickHandler(void)
 		DECREMENT_AND_TRIGGER(gCountdownToPlayNextVoice, gFlagPlayQueuedVoice);
 	#endif
 	
-	if (gFM_ScanState != FM_SCAN_OFF && gCurrentFunction != FUNCTION_MONITOR) {
-		if (gCurrentFunction != FUNCTION_TRANSMIT && gCurrentFunction != FUNCTION_RECEIVE) {
+	if (gFM_ScanState != FM_SCAN_OFF && gCurrentFunction != FUNCTION_MONITOR)
+		if (gCurrentFunction != FUNCTION_TRANSMIT && gCurrentFunction != FUNCTION_RECEIVE)
 			DECREMENT_AND_TRIGGER(gFmPlayCountdown, gScheduleFM);
-		}
-	}
-	if (gVoxStopCountdown) {
-		gVoxStopCountdown--;
-	}
-}
 
+	if (gVoxStopCountdown)
+		gVoxStopCountdown--;
+
+	#if 0
+		if (gCurrentFunction == FUNCTION_TRANSMIT || gBacklightCountdown > 0)
+		{
+			GPIO_SetBit(&GPIOB->DATA, GPIOB_PIN_BACKLIGHT);  		// turn the backlight ON
+		}
+		else
+		if (gEeprom.BACKLIGHT >= 5)
+		{	// backlight ON - half brightness
+			// was hoping to use this but don't like the odd flicker
+			if (gGlobalSysTickCounter & 1)
+				GPIO_SetBit(&GPIOB->DATA, GPIOB_PIN_BACKLIGHT);  	// turn the backlight ON
+			else
+				GPIO_ClearBit(&GPIOB->DATA, GPIOB_PIN_BACKLIGHT);	// turn the backlight OFF
+		}
+		else
+			GPIO_ClearBit(&GPIOB->DATA, GPIOB_PIN_BACKLIGHT);		// turn the backlight OFF
+	#endif
+}