diff --git a/app/aircopy.c b/app/aircopy.c
index c02f716..8478997 100644
--- a/app/aircopy.c
+++ b/app/aircopy.c
@@ -203,9 +203,9 @@ void AIRCOPY_stop_fsk_tx(void)
 	g_fsk_tx_timeout_10ms = 0;
 
 	// disable the TX
-	BK4819_SetupPowerAmplifier(0, 0);                     //
-	BK4819_set_GPIO_pin(BK4819_GPIO5_PIN1, false);        // ???
-	BK4819_set_GPIO_pin(BK4819_GPIO1_PIN29_RED, false);   // LED off
+	BK4819_SetupPowerAmplifier(0, 0);                             //
+	BK4819_set_GPIO_pin(BK4819_GPIO5_PIN1_UNKNOWN, false);        // ???
+	BK4819_set_GPIO_pin(BK4819_GPIO1_PIN29_RED, false);           // LED off
 
 	BK4819_reset_fsk();
 
diff --git a/app/app.c b/app/app.c
index cdf27a0..1907ee5 100644
--- a/app/app.c
+++ b/app/app.c
@@ -1325,7 +1325,7 @@ void APP_process(void)
 
 				BK4819_DisableVox();
 				BK4819_Sleep();
-				BK4819_set_GPIO_pin(BK4819_GPIO6_PIN2, false);
+				BK4819_set_GPIO_pin(BK4819_GPIO6_PIN2_UNKNOWN, false);
 
 				// Authentic device checked removed
 
@@ -1699,7 +1699,7 @@ void APP_time_slice_10ms(void)
 
 						RADIO_EnableCxCSS();
 						BK4819_SetupPowerAmplifier(0, 0);
-						BK4819_set_GPIO_pin(BK4819_GPIO5_PIN1, false);      // ???
+						BK4819_set_GPIO_pin(BK4819_GPIO5_PIN1_UNKNOWN, false);      // ???
 						BK4819_Enable_AfDac_DiscMode_TxDsp();
 						BK4819_set_GPIO_pin(BK4819_GPIO1_PIN29_RED, false); // LED off
 
diff --git a/app/spectrum.c b/app/spectrum.c
index 84e0e49..8dbaf38 100644
--- a/app/spectrum.c
+++ b/app/spectrum.c
@@ -434,8 +434,8 @@ static void ToggleTX(bool on) {
 
     SetF(fMeasure);
   }
-  BK4819_set_GPIO_pin(BK4819_GPIO6_PIN2, !on);
-  BK4819_set_GPIO_pin(BK4819_GPIO5_PIN1, on);
+  BK4819_set_GPIO_pin(BK4819_GPIO6_PIN2_UNKNOWN, !on);
+  BK4819_set_GPIO_pin(BK4819_GPIO5_PIN1_UNKNOWN, on);
 }
 
 // Scan info
diff --git a/driver/bk4819-regs.h b/driver/bk4819-regs.h
index 2e44c07..0feabdf 100644
--- a/driver/bk4819-regs.h
+++ b/driver/bk4819-regs.h
@@ -17,7 +17,7 @@
 #ifndef BK4819_REGS_H
 #define BK4819_REGS_H
 
-enum BK4819_REGISTER_t {
+enum bk4819_register_e {
 	BK4819_REG_00 = 0x00U,
 	BK4819_REG_02 = 0x02U,
 	BK4819_REG_06 = 0x06U,
@@ -89,22 +89,20 @@ enum BK4819_REGISTER_t {
 	BK4819_REG_7B = 0x7BU,
 	BK4819_REG_7C = 0x7CU,
 	BK4819_REG_7D = 0x7DU,
-	BK4819_REG_7E = 0x7EU,
+	BK4819_REG_7E = 0x7EU
 };
+typedef enum bk4819_register_e bk4819_register_t;
 
-typedef enum BK4819_REGISTER_t BK4819_REGISTER_t;
-
-enum BK4819_GPIO_PIN_t {
-	BK4819_GPIO6_PIN2        = 0,
-	BK4819_GPIO5_PIN1        = 1,
-	BK4819_GPIO4_PIN32       = 2,
-	BK4819_GPIO3_PIN31       = 3,
-	BK4819_GPIO2_PIN30       = 4,
-	BK4819_GPIO1_PIN29_RED   = 5,
-	BK4819_GPIO0_PIN28_GREEN = 6,
+enum bk4819_gpio_pin_e {
+	BK4819_GPIO6_PIN2_UNKNOWN = 0,   // please let us know if you know what this pin does
+	BK4819_GPIO5_PIN1_UNKNOWN = 1,   //    "            "
+	BK4819_GPIO4_PIN32_UNUSED = 2,
+	BK4819_GPIO3_PIN31_UHF    = 3,
+	BK4819_GPIO2_PIN30_VHF    = 4,
+	BK4819_GPIO1_PIN29_RED    = 5,
+	BK4819_GPIO0_PIN28_GREEN  = 6
 };
-
-typedef enum BK4819_GPIO_PIN_t BK4819_GPIO_PIN_t;
+typedef enum bk4819_gpio_pin_e bk4819_gpio_pin_t;
 
 // REG 02
 
@@ -350,4 +348,3 @@ enum {
 };
 
 #endif
-
diff --git a/driver/bk4819.c b/driver/bk4819.c
index 12e3e76..adc986f 100644
--- a/driver/bk4819.c
+++ b/driver/bk4819.c
@@ -138,7 +138,7 @@ static uint16_t BK4819_ReadU16(void)
 	return Value;
 }
 
-uint16_t BK4819_ReadRegister(BK4819_REGISTER_t Register)
+uint16_t BK4819_ReadRegister(bk4819_register_t Register)
 {
 	uint16_t Value;
 
@@ -160,7 +160,7 @@ uint16_t BK4819_ReadRegister(BK4819_REGISTER_t Register)
 	return Value;
 }
 
-void BK4819_WriteRegister(BK4819_REGISTER_t Register, uint16_t Data)
+void BK4819_WriteRegister(bk4819_register_t Register, uint16_t Data)
 {
 	GPIO_SetBit(&GPIOC->DATA, GPIOC_PIN_BK4819_SCN);
 	GPIO_ClearBit(&GPIOC->DATA, GPIOC_PIN_BK4819_SCL);
@@ -345,7 +345,7 @@ void BK4819_SetAGC(uint8_t Value)
 	}
 }
 
-void BK4819_set_GPIO_pin(BK4819_GPIO_PIN_t Pin, bool bSet)
+void BK4819_set_GPIO_pin(bk4819_gpio_pin_t Pin, bool bSet)
 {
 	if (bSet)
 		gBK4819_GpioOutState |=  (0x40u >> Pin);
@@ -862,20 +862,20 @@ void BK4819_RX_TurnOn(void)
 void BK4819_PickRXFilterPathBasedOnFrequency(uint32_t Frequency)
 {
 	if (Frequency < 28000000)
-	{
-		BK4819_set_GPIO_pin(BK4819_GPIO2_PIN30, true);
-		BK4819_set_GPIO_pin(BK4819_GPIO3_PIN31, false);
+	{	// VHF
+		BK4819_set_GPIO_pin(BK4819_GPIO2_PIN30_VHF, true);
+		BK4819_set_GPIO_pin(BK4819_GPIO3_PIN31_UHF, false);
 	}
 	else
 	if (Frequency == 0xFFFFFFFF)
-	{
-		BK4819_set_GPIO_pin(BK4819_GPIO2_PIN30, false);
-		BK4819_set_GPIO_pin(BK4819_GPIO3_PIN31, false);
+	{	// OFF
+		BK4819_set_GPIO_pin(BK4819_GPIO2_PIN30_VHF, false);
+		BK4819_set_GPIO_pin(BK4819_GPIO3_PIN31_UHF, false);
 	}
 	else
-	{
-		BK4819_set_GPIO_pin(BK4819_GPIO2_PIN30, false);
-		BK4819_set_GPIO_pin(BK4819_GPIO3_PIN31, true);
+	{	// UHF
+		BK4819_set_GPIO_pin(BK4819_GPIO2_PIN30_VHF, false);
+		BK4819_set_GPIO_pin(BK4819_GPIO3_PIN31_UHF, true);
 	}
 }
 
@@ -1199,7 +1199,7 @@ void BK4819_Conditional_RX_TurnOn_and_GPIO6_Enable(void)
 {
 	if (g_rx_idle_mode)
 	{
-		BK4819_set_GPIO_pin(BK4819_GPIO6_PIN2, true);
+		BK4819_set_GPIO_pin(BK4819_GPIO6_PIN2_UNKNOWN, true);
 		BK4819_RX_TurnOn();
 	}
 }
diff --git a/driver/bk4819.h b/driver/bk4819.h
index acd2652..e90a825 100644
--- a/driver/bk4819.h
+++ b/driver/bk4819.h
@@ -62,14 +62,14 @@ typedef enum BK4819_CSS_scan_result_e BK4819_CSS_scan_result_t;
 extern bool g_rx_idle_mode;
 
 void     BK4819_Init(void);
-uint16_t BK4819_ReadRegister(BK4819_REGISTER_t Register);
-void     BK4819_WriteRegister(BK4819_REGISTER_t Register, uint16_t Data);
+uint16_t BK4819_ReadRegister(bk4819_register_t Register);
+void     BK4819_WriteRegister(bk4819_register_t Register, uint16_t Data);
 void     BK4819_WriteU8(uint8_t Data);
 void     BK4819_WriteU16(uint16_t Data);
 
 void     BK4819_SetAGC(uint8_t Value);
 
-void     BK4819_set_GPIO_pin(BK4819_GPIO_PIN_t Pin, bool bSet);
+void     BK4819_set_GPIO_pin(bk4819_gpio_pin_t Pin, bool bSet);
 
 void     BK4819_SetCDCSSCodeWord(uint32_t CodeWord);
 void     BK4819_SetCTCSSFrequency(uint32_t BaudRate);
diff --git a/firmware.bin b/firmware.bin
index 41b0148..9c99c58 100644
Binary files a/firmware.bin and b/firmware.bin differ
diff --git a/firmware.packed.bin b/firmware.packed.bin
index deb4121..649b721 100644
Binary files a/firmware.packed.bin and b/firmware.packed.bin differ
diff --git a/functions.c b/functions.c
index 001337c..94d0498 100644
--- a/functions.c
+++ b/functions.c
@@ -163,7 +163,7 @@ void FUNCTION_Select(function_type_t Function)
 			BK4819_DisableVox();			
 			BK4819_Sleep();
 
-			BK4819_set_GPIO_pin(BK4819_GPIO6_PIN2, false);
+			BK4819_set_GPIO_pin(BK4819_GPIO6_PIN2_UNKNOWN, false);
 
 			g_update_status = true;
 
diff --git a/radio.c b/radio.c
index c77fac1..280d410 100644
--- a/radio.c
+++ b/radio.c
@@ -630,7 +630,7 @@ void RADIO_setup_registers(bool switch_to_function_0)
 
 	BK4819_set_GPIO_pin(BK4819_GPIO1_PIN29_RED, false);   // LED off
 	BK4819_SetupPowerAmplifier(0, 0);
-	BK4819_set_GPIO_pin(BK4819_GPIO5_PIN1, false);        // ???
+	BK4819_set_GPIO_pin(BK4819_GPIO5_PIN1_UNKNOWN, false);        // ???
 
 	while (1)
 	{	// wait for the interrupt to clear ?
@@ -662,7 +662,7 @@ void RADIO_setup_registers(bool switch_to_function_0)
 	BK4819_PickRXFilterPathBasedOnFrequency(Frequency);
 
 	// what does this in do ?
-	BK4819_set_GPIO_pin(BK4819_GPIO6_PIN2, true);
+	BK4819_set_GPIO_pin(BK4819_GPIO6_PIN2_UNKNOWN, true);
 
 	// AF RX Gain and DAC
 	BK4819_WriteRegister(BK4819_REG_48, 0xB3A8);  // 1011 00 111010 1000
@@ -850,7 +850,7 @@ void RADIO_enableTX(const bool fsk_tx)
 
 	g_enable_speaker = false;
 
-	BK4819_set_GPIO_pin(BK4819_GPIO6_PIN2, false);     // ???
+	BK4819_set_GPIO_pin(BK4819_GPIO6_PIN2_UNKNOWN, false);     // ???
 
 	#pragma GCC diagnostic push
 	#pragma GCC diagnostic ignored "-Wimplicit-fallthrough="
@@ -876,7 +876,7 @@ void RADIO_enableTX(const bool fsk_tx)
 	BK4819_SetCompander((!fsk_tx && g_rx_vfo->am_mode == 0 && (g_rx_vfo->compander == 1 || g_rx_vfo->compander >= 3)) ? g_rx_vfo->compander : 0);
 	BK4819_PrepareTransmit();
 	BK4819_PickRXFilterPathBasedOnFrequency(g_current_vfo->p_tx->frequency);
-	BK4819_set_GPIO_pin(BK4819_GPIO5_PIN1, true);                       // ???
+	BK4819_set_GPIO_pin(BK4819_GPIO5_PIN1_UNKNOWN, true);                       // ???
 	if (g_screen_to_display != DISPLAY_AIRCOPY)
 		BK4819_SetupPowerAmplifier(g_current_vfo->txp_calculated_setting, g_current_vfo->p_tx->frequency);
 	else