NexusX(R) swap rx/tx pins for port A, B, C if configured as CRSF receiver

src/main/common/log.h

@@ -30,6 +30,7 @@ typedef enum {
     LOG_TOPIC_POS_ESTIMATOR,    // 8, mask = 256
     LOG_TOPIC_VTX,              // 9, mask = 512
     LOG_TOPIC_OSD,              // 10, mask = 1024
+    LOG_TOPIC_SERIAL,           // 11, mask = 2048
 
     LOG_TOPIC_COUNT,
 } logTopic_e;

src/main/config/parameter_group_ids.h

@@ -132,7 +132,8 @@
 #define PG_GEOZONE_CONFIG 1042
 #define PG_GEOZONES 1043
 #define PG_GEOZONE_VERTICES 1044
-#define PG_INAV_END PG_GEOZONE_VERTICES
+#define PG_CRSFRXPORT_CONFIG 1045
+#define PG_INAV_END PG_CRSFRXPORT_CONFIG 
 
 // OSD configuration (subject to change)
 //#define PG_OSD_FONT_CONFIG 2047

src/main/drivers/serial.h

@@ -53,6 +53,8 @@ typedef enum portOptions_t {
 
     SERIAL_LONGSTOP      = 0 << 6,
     SERIAL_SHORTSTOP     = 1 << 6,
+
+    SERIAL_RXTX_SWAP     = 1 << 7
 } portOptions_t;
 
 typedef void (*serialReceiveCallbackPtr)(uint16_t data, void *rxCallbackData);   // used by serial drivers to return frames to app

src/main/drivers/serial_uart_hal.c

@@ -27,6 +27,7 @@
 #include "platform.h"
 
 #include "build/build_config.h"
+#include "build/debug.h"
 
 #include "common/utils.h"
 #include "drivers/io.h"
@@ -86,6 +87,11 @@ static void uartReconfigure(uartPort_t *uartPort)
 
     usartConfigurePinInversion(uartPort);
 
+    if (uartPort->port.options & SERIAL_RXTX_SWAP)
+    {
+      SET_BIT(uartPort->USARTx->CR2, USART_CR2_SWAP);
+    }
+
     if (uartPort->port.options & SERIAL_BIDIR)
     {
         HAL_HalfDuplex_Init(&uartPort->Handle);
@@ -111,6 +117,7 @@ static void uartReconfigure(uartPort_t *uartPort)
         /* Enable the UART Transmit Data Register Empty Interrupt */
         SET_BIT(uartPort->USARTx->CR1, USART_CR1_TXEIE);
     }
+
     return;
 }
 
@@ -155,7 +162,6 @@ serialPort_t *uartOpen(USART_TypeDef *USARTx, serialReceiveCallbackPtr callback,
         return (serialPort_t *)s;
     }
 
-
     // common serial initialisation code should move to serialPort::init()
     s->port.rxBufferHead = s->port.rxBufferTail = 0;
     s->port.txBufferHead = s->port.txBufferTail = 0;

src/main/fc/config.c

@@ -131,6 +131,13 @@ PG_RESET_TEMPLATE(beeperConfig_t, beeperConfig,
                   .pwmMode = SETTING_BEEPER_PWM_MODE_DEFAULT,
 );
 
+PG_REGISTER_WITH_RESET_TEMPLATE(crsfRxPortConfig_t, crsfRxPortConfig, PG_CRSFRXPORT_CONFIG, 1);
+
+PG_RESET_TEMPLATE(crsfRxPortConfig_t, crsfRxPortConfig,
+                  .swap = 0,
+                  .preferred_swap = 0
+);
+
 PG_REGISTER_WITH_RESET_TEMPLATE(adcChannelConfig_t, adcChannelConfig, PG_ADC_CHANNEL_CONFIG, 0);
 
 PG_RESET_TEMPLATE(adcChannelConfig_t, adcChannelConfig,

src/main/fc/config.h

@@ -94,6 +94,13 @@ typedef struct beeperConfig_s {
 
 PG_DECLARE(beeperConfig_t, beeperConfig);
 
+typedef struct CrsfRxPortConfig_s {
+    bool swap;
+    bool preferred_swap;
+} crsfRxPortConfig_t;
+
+PG_DECLARE(crsfRxPortConfig_t, crsfRxPortConfig);
+
 typedef struct adcChannelConfig_s {
     uint8_t adcFunctionChannel[ADC_FUNCTION_COUNT];
 } adcChannelConfig_t;

src/main/fc/settings.yaml

@@ -4244,6 +4244,16 @@ groups:
         default_value: OFF
         description: "Allows disabling PWM mode for beeper on some targets. Switch from ON to OFF if the external beeper sound is weak. Do not switch from OFF to ON without checking if the board supports PWM beeper mode"
 
+  - name: PG_CRSFRXPORT_CONFIG
+    type: crsfRxPortConfig_t
+    headers: [ "fc/config.h" ]
+    members:
+      - name: crsf_rx_swap
+        field: swap
+        type: bool
+        default_value: OFF
+        description: "Swaps rx/tx for CRSF RX uart"
+
   - name: PG_POWER_LIMITS_CONFIG
     type: powerLimitsConfig_t
     headers: ["flight/power_limits.h"]

src/main/rx/crsf.c

@@ -29,6 +29,7 @@
 #include "common/crc.h"
 #include "common/maths.h"
 #include "common/utils.h"
+#include "common/log.h"
 
 #include "drivers/time.h"
 #include "drivers/serial.h"
@@ -329,13 +330,25 @@ bool crsfRxInit(const rxConfig_t *rxConfig, rxRuntimeConfig_t *rxRuntimeConfig)
         return false;
     }
 
+    portOptions_t options = CRSF_PORT_OPTIONS | (tristateWithDefaultOffIsActive(rxConfig->halfDuplex) ? SERIAL_BIDIR : 0);
+
+#if defined(NEXUSX)
+    if ((portConfig->identifier == SERIAL_PORT_USART3) || // Port C
+        (portConfig->identifier == SERIAL_PORT_USART4) || // Port A
+        (portConfig->identifier == SERIAL_PORT_USART6))   // Port B
+    {
+      LOG_DEBUG(SERIAL, "crsfRxInit rxtx swap");
+      options |= SERIAL_RXTX_SWAP;
+    }
+#endif
+
     serialPort = openSerialPort(portConfig->identifier,
         FUNCTION_RX_SERIAL,
         crsfDataReceive,
         NULL,
         CRSF_BAUDRATE,
         CRSF_PORT_MODE,
-        CRSF_PORT_OPTIONS | (tristateWithDefaultOffIsActive(rxConfig->halfDuplex) ? SERIAL_BIDIR : 0)
+        options
         );
 
     return serialPort != NULL;