diff --git a/nuttx/ChangeLog b/nuttx/ChangeLog
index befaf0f77..9a7421070 100644
--- a/nuttx/ChangeLog
+++ b/nuttx/ChangeLog
@@ -3029,4 +3029,9 @@
 	  add the ability to run the chip off the internal oscillator.  There is no open
 	  board configuration for this part yet (the STM32VLDiscovery would be a candidate).
 	  Contributed by Mike Smith.
+	* arch/arm/src/stm32: Fixed typos in conditional compilation in the CAN and DMA
+	  and some pin configuration.  This would have caused problems for STM32 F107xx.
+	  Typos noted by Mike Smith.
+	* arch/arm/src/lpc43xx/lpc43_serial.c:  Add support for certain RS-485 features
+	  in the serial driver (still a work in progress on initial check-in).
 
diff --git a/nuttx/arch/arm/src/lpc43xx/lpc43_serial.c b/nuttx/arch/arm/src/lpc43xx/lpc43_serial.c
index 1c4e56fe4..bfee7a222 100644
--- a/nuttx/arch/arm/src/lpc43xx/lpc43_serial.c
+++ b/nuttx/arch/arm/src/lpc43xx/lpc43_serial.c
@@ -857,6 +857,50 @@ static int up_interrupt(int irq, void *context)
     return OK;
 }
 
+/****************************************************************************
+ * Name: up_set_rs485_mode
+ *
+ * Description:
+ *   Handle LPC43xx USART0,2,3 RS485 mode set ioctl (TIOCSRS485) to enable
+ *   and disable RS-485 mode.  This is part of the serial ioctl logic.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_USART_RS485MODE
+static inline int up_set_rs485_mode(struct up_dev_s *priv,
+                                    const struct serial_rs485 *mode)
+{
+  irqstate_t flags;
+
+  DEBUGASSERT(priv && mode);
+  flags = irqsave();
+#warning "Missing logic"
+  irqrestore(flags);
+}
+#endif
+
+/****************************************************************************
+ * Name: up_get_rs485_mode
+ *
+ * Description:
+ *   Handle LPC43xx USART0,2,3 RS485 mode get ioctl (TIOCGRS485) to get the
+ *   current RS-485 mode.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_USART_RS485MODE
+static inline int up_get_rs485_mode(struct up_dev_s *priv,
+                                    struct serial_rs485 *mode)
+{
+  irqstate_t flags;
+
+  DEBUGASSERT(priv && mode);
+  flags = irqsave();
+#warning "Missing logic"
+  irqrestore(flags);
+}
+#endif
+
 /****************************************************************************
  * Name: up_ioctl
  *
@@ -906,6 +950,22 @@ static int up_ioctl(struct file *filep, int cmd, unsigned long arg)
       }
       break;
 
+#ifdef CONFIG_USART_RS485MODE
+    case TIOCSRS485:  /* Set RS485 mode, arg: pointer to struct serial_rs485 */
+      {
+        ret = up_set_rs485_mode(priv,
+                                (const struct serial_rs485 *)((uintptr_t)arg));
+      }
+      break;
+
+    case TIOCGRS485:  /* Get RS485 mode, arg: pointer to struct serial_rs485 */
+      {
+        ret = up_get_rs485_mode(priv,
+                                (struct serial_rs485 *)((uintptr_t)arg));
+      }
+      break;
+#endif
+
     default:
       *get_errno_ptr() = ENOTTY;
       ret = ERROR;
diff --git a/nuttx/configs/lpc4330-xplorer/README.txt b/nuttx/configs/lpc4330-xplorer/README.txt
index 5a58d3769..3e89b478f 100644
--- a/nuttx/configs/lpc4330-xplorer/README.txt
+++ b/nuttx/configs/lpc4330-xplorer/README.txt
@@ -716,7 +716,7 @@ LPC4330-Xplorer Configuration Options
       CONFIG_LPC43_USB1_ULPI=y
       CONFIG_LPC43_WWDT=y
 
-  LPC43xx specific device driver settings
+  LPC43xx specific U[S]ART device driver settings
 
     CONFIG_U[S]ARTn_SERIAL_CONSOLE - selects the UARTn for the
        console and ttys0 (default is the USART0).
@@ -729,6 +729,10 @@ LPC4330-Xplorer Configuration Options
     CONFIG_U[S]ARTn_PARTIY - 0=no parity, 1=odd parity, 2=even parity
     CONFIG_U[S]ARTn_2STOP - Two stop bits
 
+    CONFIG_USART_RS485MODE - Support LPC43xx USART0,2,3 RS485 mode
+      ioctls (TIOCSRS485 and TIOCGRS485) to enable and disable
+      RS-485 mode.
+  
   LPC43xx specific CAN device driver settings.  These settings all
   require CONFIG_CAN:
 
diff --git a/nuttx/configs/lpc4330-xplorer/nsh/defconfig b/nuttx/configs/lpc4330-xplorer/nsh/defconfig
index deb3ff19e..8f6660ede 100644
--- a/nuttx/configs/lpc4330-xplorer/nsh/defconfig
+++ b/nuttx/configs/lpc4330-xplorer/nsh/defconfig
@@ -227,6 +227,13 @@ CONFIG_UART1_2STOP=0
 CONFIG_USART2_2STOP=0
 CONFIG_USART3_2STOP=0
 
+#
+# CONFIG_USART_RS485MODE - Support LPC43xx USART0,2,3 RS485 mode
+#   ioctls (TIOCSRS485 and TIOCGRS485) to enable and disable
+#   RS-485 mode.
+#
+CONFIG_USART_RS485MODE=n
+
 #
 # LPC43xx specific PHY/Ethernet device driver settings
 #
diff --git a/nuttx/configs/lpc4330-xplorer/ostest/defconfig b/nuttx/configs/lpc4330-xplorer/ostest/defconfig
index c20897b76..202192635 100644
--- a/nuttx/configs/lpc4330-xplorer/ostest/defconfig
+++ b/nuttx/configs/lpc4330-xplorer/ostest/defconfig
@@ -227,6 +227,13 @@ CONFIG_UART1_2STOP=0
 CONFIG_USART2_2STOP=0
 CONFIG_USART3_2STOP=0
 
+#
+# CONFIG_USART_RS485MODE - Support LPC43xx USART0,2,3 RS485 mode
+#   ioctls (TIOCSRS485 and TIOCGRS485) to enable and disable
+#   RS-485 mode.
+#
+CONFIG_USART_RS485MODE=n
+
 #
 # LPC43xx specific PHY/Ethernet device driver settings
 #
diff --git a/nuttx/include/nuttx/serial/tioctl.h b/nuttx/include/nuttx/serial/tioctl.h
index a3ce2c7d3..a923fa324 100644
--- a/nuttx/include/nuttx/serial/tioctl.h
+++ b/nuttx/include/nuttx/serial/tioctl.h
@@ -160,9 +160,21 @@
 #define TIOCMIWAIT      _TIOC(0x0028)  /* Wait for a change on serial input line(s): void */
 #define TIOCGICOUNT     _TIOC(0x0029)  /* Read serial port interrupt count: FAR  struct serial_icounter_struct */
 
+/* RS-485 Support */
+
+#define TIOCSRS485      _TIOC(0x002a)  /* Set RS485 mode, arg: pointer to struct serial_rs485 */
+#define TIOCGRS485      _TIOC(0x002b)  /* Get RS485 mode, arg: pointer to struct serial_rs485 */
+
 /* Debugging */
 
-#define TIOCSERGSTRUCT  _TIOC(0x002a) /* Get device TTY structure */
+#define TIOCSERGSTRUCT  _TIOC(0x002c) /* Get device TTY structure */
+
+/* Definitions used in struct serial_rs485 (Linux compatible) */
+
+#define SER_RS485_ENABLED        (1 << 0) /* Enable/disble RS-485 support */
+#define SER_RS485_RTS_ON_SEND    (1 << 1) /* Logic level for RTS pin when sending */
+#define SER_RS485_RTS_AFTER_SEND (1 << 2) /* Logic level for RTS pin after sent */
+#define SER_RS485_RX_DURING_TX   (1 << 4)
 
 /********************************************************************************************
  * Public Type Definitions
@@ -178,6 +190,15 @@ struct winsize
 /* uint16_t ws_ypixel;    unused */
 };
 
+/* Structure used with TIOCSRS485 and TIOCGRS485 (Linux compatible) */
+
+struct serial_rs485
+{
+  uint32_t flags                   /* See SER_RS485_* definitions */
+  uint32_t delay_rts_before_send;  /* Delay before send (milliseconds) */
+  uint32_t delay_rts_after_send;   /* Delay after send (milliseconds) */
+};
+
 /********************************************************************************************
  * Public Function Prototypes
  ********************************************************************************************/