diff --git a/docs/Board - Sparky.md b/docs/Board - Sparky.md
index af90f80904..ae0c943bba 100644
--- a/docs/Board - Sparky.md	
+++ b/docs/Board - Sparky.md	
@@ -3,6 +3,7 @@
 The Sparky is a very low cost and very powerful board.
 
 * 3 hardware serial ports.
+* Built-in serial port inverters which allows SBUS receivers to be used without external inverters.
 * USB (can be used at the same time as the serial ports).
 * 10 PWM outputs.
 * Dedicated PPM/SerialRX input pin.
@@ -16,11 +17,11 @@ Flyable!
 Tested with revision 1 board. 
 
 ## TODO
-* Mag
-* Baro
+* Baro - detection works but getting bad readings, disabled for now.
 * Led Strip
 * ADC
-* Display
+* Sonar
+* Display (via Flex port)
 * Softserial - though having 3 hardware serial ports makes it a little redundant.
 
 # Flashing
@@ -46,10 +47,12 @@ Flashing cleanflight will erase the TauLabs bootloader, this is not a problem an
 | Value | Identifier   | RX        | TX         | Notes                                                                                       |
 | ----- | ------------ | --------- | ---------- | ------------------------------------------------------------------------------------------- |
 | 1     | USB VCP      | RX (USB)  | TX (USB)   |  |
-| 2     | USART1       | RX / PB7  | TX / PB6   | Conn1 / Flexi Port |
-| 3     | USART2       | RX / PA3  | PWM6 / PA2 | On RX is on INPUT header.  Best port for Serial RX input. |
+| 2     | USART1       | RX / PB7  | TX / PB6   | Conn1 / Flexi Port. |
+| 3     | USART2       | RX / PA3  | PWM6 / PA2 | On RX is on INPUT header.  Best port for Serial RX input |
 | 4     | USART3       | RX / PB11 | TX / PB10  | RX/TX is on one end of the 6-pin header about the PWM outputs. |
 
 USB VCP *can* be used at the same time as other serial ports (unlike Naze32).
 
+All USART ports all support automatic hardware inversion which allows direct connection of serial rx receivers like the FrSky X4RSB - no external inverter needed.
+
 
diff --git a/src/main/drivers/serial_uart.c b/src/main/drivers/serial_uart.c
index 663c9ff455..7a6e83b1f0 100644
--- a/src/main/drivers/serial_uart.c
+++ b/src/main/drivers/serial_uart.c
@@ -39,6 +39,31 @@ uartPort_t *serialUSART1(uint32_t baudRate, portMode_t mode);
 uartPort_t *serialUSART2(uint32_t baudRate, portMode_t mode);
 uartPort_t *serialUSART3(uint32_t baudRate, portMode_t mode);
 
+static void usartConfigurePinInversion(uartPort_t *uartPort) {
+#ifdef INVERTER
+    if (uartPort->port.inversion == SERIAL_INVERTED && uartPort->USARTx == INVERTER_USART) {
+        // Enable hardware inverter if available.
+        INVERTER_ON;
+    }
+#endif
+
+#ifdef STM32F303xC
+    uint32_t inversionPins = 0;
+
+    if (uartPort->port.mode & MODE_TX) {
+        inversionPins |= USART_InvPin_Tx;
+    }
+    if (uartPort->port.mode & MODE_RX) {
+        inversionPins |= USART_InvPin_Rx;
+    }
+
+    // Note: inversion when using MODE_BIDIR not supported yet.
+
+    USART_InvPinCmd(uartPort->USARTx, inversionPins, uartPort->port.inversion == SERIAL_INVERTED ? ENABLE : DISABLE);
+#endif
+
+}
+
 static void uartReconfigure(uartPort_t *uartPort)
 {
     USART_InitTypeDef USART_InitStructure;
@@ -63,22 +88,16 @@ static void uartReconfigure(uartPort_t *uartPort)
         USART_InitStructure.USART_Mode |= USART_Mode_Tx | USART_Mode_Rx;
 
     USART_Init(uartPort->USARTx, &USART_InitStructure);
+
+    usartConfigurePinInversion(uartPort);
+
     USART_Cmd(uartPort->USARTx, ENABLE);
 }
 
 serialPort_t *uartOpen(USART_TypeDef *USARTx, serialReceiveCallbackPtr callback, uint32_t baudRate, portMode_t mode, serialInversion_e inversion)
 {
-    UNUSED(inversion);
-
     uartPort_t *s = NULL;
 
-#ifdef INVERTER
-    if (inversion == SERIAL_INVERTED && USARTx == INVERTER_USART) {
-        // Enable hardware inverter if available.
-        INVERTER_ON;
-    }
-#endif
-
     if (USARTx == USART1) {
         s = serialUSART1(baudRate, mode);
 #ifdef USE_USART2
@@ -101,12 +120,7 @@ serialPort_t *uartOpen(USART_TypeDef *USARTx, serialReceiveCallbackPtr callback,
     s->port.callback = callback;
     s->port.mode = mode;
     s->port.baudRate = baudRate;
-
-#if 1 // FIXME use inversion on STM32F3
-    s->port.inversion = SERIAL_NOT_INVERTED;
-#else
     s->port.inversion = inversion;
-#endif
 
     uartReconfigure(s);