Fixed serial RX to be able to use TX pin on any F4 target.

src/main/fc/cli.c

@@ -565,6 +565,9 @@ const clivalue_t valueTable[] = {
 #ifdef SERIAL_RX
     { "serialrx_provider",          VAR_UINT8  | MASTER_VALUE | MODE_LOOKUP,  &rxConfig()->serialrx_provider, .config.lookup = { TABLE_SERIAL_RX } },
 #endif
+#ifdef STM32F4
+    { "serialrx_halfduplex",        VAR_UINT8  | MASTER_VALUE | MODE_LOOKUP,  &rxConfig()->halfDuplex, .config.lookup = { TABLE_OFF_ON } },
+#endif 
 
     { "sbus_inversion",             VAR_UINT8  | MASTER_VALUE | MODE_LOOKUP,  &rxConfig()->sbus_inversion, .config.lookup = { TABLE_OFF_ON } },
 

src/main/fc/config.c

@@ -856,6 +856,7 @@ void createDefaultConfig(master_t *config)
 #else
     config->rxConfig.serialrx_provider = 0;
 #endif
+    config->rxConfig.halfDuplex = 0;
     config->rxConfig.rx_spi_protocol = RX_SPI_DEFAULT_PROTOCOL;
     config->rxConfig.sbus_inversion = 1;
     config->rxConfig.spektrum_sat_bind = 0;

src/main/rx/crsf.c

@@ -236,7 +236,13 @@ bool crsfRxInit(const rxConfig_t *rxConfig, rxRuntimeConfig_t *rxRuntimeConfig)
         return false;
     }
 
-    serialPort = openSerialPort(portConfig->identifier, FUNCTION_RX_SERIAL, crsfDataReceive, CRSF_BAUDRATE, CRSF_PORT_MODE, CRSF_PORT_OPTIONS);
+    serialPort = openSerialPort(portConfig->identifier, 
+        FUNCTION_RX_SERIAL, 
+        crsfDataReceive, 
+        CRSF_BAUDRATE, 
+        CRSF_PORT_MODE, 
+        CRSF_PORT_OPTIONS | (rxConfig->halfDuplex ? SERIAL_BIDIR : 0)
+        );
 
     return serialPort != NULL;
 }

src/main/rx/ibus.c

@@ -167,7 +167,13 @@ bool ibusInit(const rxConfig_t *rxConfig, rxRuntimeConfig_t *rxRuntimeConfig)
     bool portShared = false;
 #endif
 
-    serialPort_t *ibusPort = openSerialPort(portConfig->identifier, FUNCTION_RX_SERIAL, ibusDataReceive, IBUS_BAUDRATE, portShared ? MODE_RXTX : MODE_RX, SERIAL_NOT_INVERTED);
+    serialPort_t *ibusPort = openSerialPort(portConfig->identifier, 
+        FUNCTION_RX_SERIAL, 
+        ibusDataReceive, 
+        IBUS_BAUDRATE, 
+        portShared ? MODE_RXTX : MODE_RX, 
+        SERIAL_NOT_INVERTED | (rxConfig->halfDuplex ? SERIAL_BIDIR : 0)
+        );
 
 #ifdef TELEMETRY
     if (portShared) {

src/main/rx/jetiexbus.c

@@ -604,7 +604,13 @@ bool jetiExBusInit(const rxConfig_t *rxConfig, rxRuntimeConfig_t *rxRuntimeConfi
         return false;
     }
 
-    jetiExBusPort = openSerialPort(portConfig->identifier, FUNCTION_RX_SERIAL, jetiExBusDataReceive, JETIEXBUS_BAUDRATE, MODE_RXTX, JETIEXBUS_OPTIONS );
+    jetiExBusPort = openSerialPort(portConfig->identifier, 
+        FUNCTION_RX_SERIAL, 
+        jetiExBusDataReceive, 
+        JETIEXBUS_BAUDRATE, 
+        MODE_RXTX, 
+        JETIEXBUS_OPTIONS | (rxConfig->halfDuplex ? SERIAL_BIDIR : 0) 
+        );
     serialSetMode(jetiExBusPort, MODE_RX);
     return jetiExBusPort != NULL;
 }

src/main/rx/rx.h

@@ -114,7 +114,8 @@ typedef struct rxConfig_s {
     uint8_t rcmap[MAX_MAPPABLE_RX_INPUTS];  // mapping of radio channels to internal RPYTA+ order
     uint8_t serialrx_provider;              // type of UART-based receiver (0 = spek 10, 1 = spek 11, 2 = sbus). Must be enabled by FEATURE_RX_SERIAL first.
     uint8_t sbus_inversion;                 // default sbus (Futaba, FrSKY) is inverted. Support for uninverted OpenLRS (and modified FrSKY) receivers.
-    uint8_t rx_spi_protocol;               // type of nrf24 protocol (0 = v202 250kbps). Must be enabled by FEATURE_RX_NRF24 first.
+    uint8_t halfDuplex;                     // allow rx to operate in half duplex mode on F4, ignored for F1 and F3.
+    uint8_t rx_spi_protocol;                // type of nrf24 protocol (0 = v202 250kbps). Must be enabled by FEATURE_RX_NRF24 first.
     uint32_t rx_spi_id;
     uint8_t rx_spi_rf_channel_count;
     uint8_t spektrum_sat_bind;              // number of bind pulses for Spektrum satellite receivers

src/main/rx/sbus.c

@@ -248,8 +248,13 @@ bool sbusInit(const rxConfig_t *rxConfig, rxRuntimeConfig_t *rxRuntimeConfig)
     bool portShared = false;
 #endif
 
-    portOptions_t options = (rxConfig->sbus_inversion) ? (SBUS_PORT_OPTIONS | SERIAL_INVERTED) : SBUS_PORT_OPTIONS;
+    serialPort_t *sBusPort = openSerialPort(portConfig->identifier, 
-    serialPort_t *sBusPort = openSerialPort(portConfig->identifier, FUNCTION_RX_SERIAL, sbusDataReceive, SBUS_BAUDRATE, portShared ? MODE_RXTX : MODE_RX, options);
+        FUNCTION_RX_SERIAL, 
+        sbusDataReceive, 
+        SBUS_BAUDRATE, 
+        portShared ? MODE_RXTX : MODE_RX, 
+        SBUS_PORT_OPTIONS | (rxConfig->sbus_inversion ? SERIAL_INVERTED : 0) | (rxConfig->halfDuplex ? SERIAL_BIDIR : 0)
+        );
 
 #ifdef TELEMETRY
     if (portShared) {

src/main/rx/spektrum.c

@@ -303,7 +303,8 @@ bool spektrumInit(const rxConfig_t *rxConfig, rxRuntimeConfig_t *rxRuntimeConfig
         spektrumDataReceive,
         SPEKTRUM_BAUDRATE,
         portShared || srxlEnabled ? MODE_RXTX : MODE_RX,
-        SERIAL_NOT_INVERTED | (srxlEnabled ? SERIAL_BIDIR : 0));
+        SERIAL_NOT_INVERTED | ((srxlEnabled || rxConfig->halfDuplex) ? SERIAL_BIDIR : 0)
+        );
 
 #ifdef TELEMETRY
     if (portShared) {

src/main/rx/sumd.c

@@ -179,7 +179,13 @@ bool sumdInit(const rxConfig_t *rxConfig, rxRuntimeConfig_t *rxRuntimeConfig)
     bool portShared = false;
 #endif
 
-    serialPort_t *sumdPort = openSerialPort(portConfig->identifier, FUNCTION_RX_SERIAL, sumdDataReceive, SUMD_BAUDRATE, portShared ? MODE_RXTX : MODE_RX, SERIAL_NOT_INVERTED);
+    serialPort_t *sumdPort = openSerialPort(portConfig->identifier, 
+        FUNCTION_RX_SERIAL, 
+        sumdDataReceive, 
+        SUMD_BAUDRATE, 
+        portShared ? MODE_RXTX : MODE_RX, 
+        SERIAL_NOT_INVERTED | (rxConfig->halfDuplex ? SERIAL_BIDIR : 0)
+        );
 
 #ifdef TELEMETRY
     if (portShared) {

src/main/rx/xbus.c

@@ -329,7 +329,13 @@ bool xBusInit(const rxConfig_t *rxConfig, rxRuntimeConfig_t *rxRuntimeConfig)
     bool portShared = false;
 #endif
 
-    serialPort_t *xBusPort = openSerialPort(portConfig->identifier, FUNCTION_RX_SERIAL, xBusDataReceive, baudRate, portShared ? MODE_RXTX : MODE_RX, SERIAL_NOT_INVERTED);
+    serialPort_t *xBusPort = openSerialPort(portConfig->identifier, 
+        FUNCTION_RX_SERIAL, 
+        xBusDataReceive, 
+        baudRate, 
+        portShared ? MODE_RXTX : MODE_RX, 
+        SERIAL_NOT_INVERTED | (rxConfig->halfDuplex ? SERIAL_BIDIR : 0)
+        );
 
 #ifdef TELEMETRY
     if (portShared) {