diff --git a/configs/sam4s-xplained-pro/nsh/defconfig b/configs/sam4s-xplained-pro/nsh/defconfig
index e25f354db1..a9a10ce49a 100644
--- a/configs/sam4s-xplained-pro/nsh/defconfig
+++ b/configs/sam4s-xplained-pro/nsh/defconfig
@@ -50,6 +50,7 @@ CONFIG_ARCH_HAVE_STACKCHECK=y
 #
 # CONFIG_DEBUG_MM is not set
 # CONFIG_DEBUG_SCHED is not set
+# CONFIG_DEBUG_USB is not set
 # CONFIG_DEBUG_FS is not set
 # CONFIG_DEBUG_LIB is not set
 # CONFIG_DEBUG_BINFMT is not set
@@ -67,6 +68,7 @@ CONFIG_DEBUG_STACK=y
 # CONFIG_DEBUG_DMA is not set
 # CONFIG_DEBUG_RTC is not set
 # CONFIG_DEBUG_WATCHDOG is not set
+# CONFIG_DEBUG_TIMER is not set
 # CONFIG_DEBUG_AUDIO is not set
 CONFIG_DEBUG_SYMBOLS=y
 CONFIG_ARCH_HAVE_CUSTOMOPT=y
@@ -209,7 +211,7 @@ CONFIG_SAM34_RTC=y
 CONFIG_SAM34_SMC=y
 # CONFIG_SAM34_SPI0 is not set
 # CONFIG_SAM34_SSC is not set
-# CONFIG_SAM34_TC0 is not set
+CONFIG_SAM34_TC0=y
 # CONFIG_SAM34_TC1 is not set
 # CONFIG_SAM34_TC2 is not set
 # CONFIG_SAM34_TC3 is not set
@@ -221,7 +223,7 @@ CONFIG_SAM34_SMC=y
 # CONFIG_SAM34_TWIS1 is not set
 CONFIG_SAM34_UART0=y
 CONFIG_SAM34_UART1=y
-# CONFIG_SAM34_UDP is not set
+CONFIG_SAM34_UDP=y
 # CONFIG_SAM34_USART0 is not set
 CONFIG_SAM34_USART1=y
 CONFIG_SAM34_WDT=y
@@ -246,20 +248,25 @@ CONFIG_SAM34_GPIOC_IRQ=y
 #
 # AT91SAM3/4 HSMCI device driver options
 #
-CONFIG_SAM34_HSMCI_RDPROOF=y
-CONFIG_SAM34_HSMCI_WRPROOF=y
+# CONFIG_SAM34_HSMCI_RDPROOF is not set
+# CONFIG_SAM34_HSMCI_WRPROOF is not set
+
+#
+# AT91SAM3/4 USB Full Speed Device Controller driver (DCD) options
+#
+# CONFIG_SAM34_UDP_REGDEBUG is not set
 
 #
 # AT91SAM3/4 Watchdog Configuration
 #
 CONFIG_WDT_ENABLED_ON_RESET=y
 # CONFIG_WDT_DISABLE_ON_RESET is not set
-CONFIG_WDT_TIMEOUT=4000
-CONFIG_WDT_MINTIME=2000
+CONFIG_WDT_TIMEOUT=5000
+CONFIG_WDT_MINTIME=2500
 CONFIG_WDT_THREAD=y
 CONFIG_WDT_THREAD_NAME="wdog"
-CONFIG_WDT_THREAD_INTERVAL=2000
-CONFIG_WDT_THREAD_PRIORITY=220
+CONFIG_WDT_THREAD_INTERVAL=2500
+CONFIG_WDT_THREAD_PRIORITY=200
 CONFIG_WDT_THREAD_STACKSIZE=512
 
 #
@@ -431,7 +438,7 @@ CONFIG_PTHREAD_STACK_DEFAULT=4096
 #
 # Device Drivers
 #
-# CONFIG_DISABLE_POLL is not set
+CONFIG_DISABLE_POLL=y
 CONFIG_DEV_NULL=y
 CONFIG_DEV_ZERO=y
 # CONFIG_LOOP is not set
@@ -448,6 +455,7 @@ CONFIG_RTC_DATETIME=y
 CONFIG_RTC_ALARM=y
 CONFIG_WATCHDOG=y
 CONFIG_WATCHDOG_DEVPATH="/dev/watchdog0"
+CONFIG_TIMER=y
 # CONFIG_ANALOG is not set
 # CONFIG_AUDIO_DEVICES is not set
 # CONFIG_VIDEO_DEVICES is not set
@@ -473,6 +481,7 @@ CONFIG_PIPES=y
 # CONFIG_SERCOMM_CONSOLE is not set
 CONFIG_SERIAL=y
 # CONFIG_DEV_LOWCONSOLE is not set
+CONFIG_SERIAL_REMOVABLE=y
 # CONFIG_16550_UART is not set
 # CONFIG_ARCH_HAVE_UART is not set
 CONFIG_ARCH_HAVE_UART0=y
@@ -502,7 +511,6 @@ CONFIG_ARCH_HAVE_USART1=y
 CONFIG_USART1_ISUART=y
 CONFIG_MCU_SERIAL=y
 CONFIG_STANDARD_SERIAL=y
-CONFIG_SERIAL_NPOLLWAITERS=2
 # CONFIG_SERIAL_TIOCSERGSTRUCT is not set
 CONFIG_UART0_SERIAL_CONSOLE=y
 # CONFIG_UART1_SERIAL_CONSOLE is not set
@@ -546,7 +554,48 @@ CONFIG_USART1_2STOP=0
 # CONFIG_USART1_OFLOWCONTROL is not set
 # CONFIG_SERIAL_IFLOWCONTROL is not set
 # CONFIG_SERIAL_OFLOWCONTROL is not set
-# CONFIG_USBDEV is not set
+CONFIG_USBDEV=y
+
+#
+# USB Device Controller Driver Options
+#
+# CONFIG_USBDEV_ISOCHRONOUS is not set
+# CONFIG_USBDEV_DUALSPEED is not set
+CONFIG_USBDEV_SELFPOWERED=y
+# CONFIG_USBDEV_BUSPOWERED is not set
+CONFIG_USBDEV_MAXPOWER=100
+# CONFIG_USBDEV_DMA is not set
+CONFIG_ARCH_USBDEV_STALLQUEUE=y
+# CONFIG_USBDEV_TRACE is not set
+
+#
+# USB Device Class Driver Options
+#
+# CONFIG_USBDEV_COMPOSITE is not set
+# CONFIG_PL2303 is not set
+CONFIG_CDCACM=y
+CONFIG_CDCACM_DEVMINOR=0
+# CONFIG_CDCACM_CONSOLE is not set
+CONFIG_CDCACM_EP0MAXPACKET=64
+CONFIG_CDCACM_EPINTIN=1
+CONFIG_CDCACM_EPINTIN_FSSIZE=64
+CONFIG_CDCACM_EPINTIN_HSSIZE=64
+CONFIG_CDCACM_EPBULKOUT=3
+CONFIG_CDCACM_EPBULKOUT_FSSIZE=64
+CONFIG_CDCACM_EPBULKOUT_HSSIZE=512
+CONFIG_CDCACM_EPBULKIN=2
+CONFIG_CDCACM_EPBULKIN_FSSIZE=64
+CONFIG_CDCACM_EPBULKIN_HSSIZE=512
+CONFIG_CDCACM_NWRREQS=4
+CONFIG_CDCACM_NRDREQS=4
+CONFIG_CDCACM_BULKIN_REQLEN=250
+CONFIG_CDCACM_RXBUFSIZE=1024
+CONFIG_CDCACM_TXBUFSIZE=1024
+CONFIG_CDCACM_VENDORID=0x0525
+CONFIG_CDCACM_PRODUCTID=0xa4a7
+CONFIG_CDCACM_VENDORSTR="NuttX"
+CONFIG_CDCACM_PRODUCTSTR="CDC/ACM Serial"
+# CONFIG_USBMSC is not set
 # CONFIG_USBHOST is not set
 # CONFIG_WIRELESS is not set
 
@@ -639,8 +688,8 @@ CONFIG_BUILTIN=y
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
-# CONFIG_STDIO_LINEBUFFER is not set
+CONFIG_STDIO_BUFFER_SIZE=256
+CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=2
 # CONFIG_LIBM is not set
 # CONFIG_NOPRINTF_FIELDWIDTH is not set
@@ -733,6 +782,7 @@ CONFIG_EXAMPLES_NSH_CXXINITIALIZE=y
 # CONFIG_EXAMPLES_ROMFS is not set
 # CONFIG_EXAMPLES_SENDMAIL is not set
 CONFIG_EXAMPLES_SERIALBLASTER=y
+CONFIG_EXAMPLES_SERIALRX=y
 # CONFIG_EXAMPLES_SERLOOP is not set
 # CONFIG_EXAMPLES_SLCD is not set
 # CONFIG_EXAMPLES_SMART_TEST is not set
@@ -856,10 +906,12 @@ CONFIG_NSH_NESTDEPTH=3
 # CONFIG_NSH_DISABLE_LOOPS is not set
 # CONFIG_NSH_DISABLEBG is not set
 CONFIG_NSH_CONSOLE=y
+# CONFIG_NSH_USBCONSOLE is not set
 
 #
 # USB Trace Support
 #
+# CONFIG_NSH_USBDEV_TRACE is not set
 CONFIG_NSH_CONDEV="/dev/console"
 CONFIG_NSH_ARCHINIT=y
 
@@ -933,7 +985,7 @@ CONFIG_READLINE_ECHO=y
 #
 # SD Card
 #
-CONFIG_SYSTEM_SDCARD=y
+# CONFIG_SYSTEM_SDCARD is not set
 
 #
 # Sysinfo
@@ -957,6 +1009,7 @@ CONFIG_SYSTEM_STACKMONITOR_INTERVAL=2
 #
 # USB CDC/ACM Device Commands
 #
+# CONFIG_SYSTEM_CDCACM is not set
 
 #
 # USB Composite Device Commands
diff --git a/configs/sam4s-xplained-pro/src/sam4s-xplained-pro.h b/configs/sam4s-xplained-pro/src/sam4s-xplained-pro.h
index e4a6fc4ca1..fbc9391565 100644
--- a/configs/sam4s-xplained-pro/src/sam4s-xplained-pro.h
+++ b/configs/sam4s-xplained-pro/src/sam4s-xplained-pro.h
@@ -57,7 +57,7 @@
 
 #define HAVE_HSMCI      1
 #define HAVE_PROC       1
-#define HAVE_USBDEV     0
+#define HAVE_USBDEV     1
 #undef  HAVE_USBMONITOR
 
 /* HSMCI */
@@ -95,7 +95,7 @@
  * device.
  */
 
-#if !defined(CONFIG_SAM34_UDP) || !defined(CONFIG_USBDEV)
+#if !defined(CONFIG_SAM34_UDP) || !defined(CONFIG_USBDEV) ||!defined(CONFIG_CDCACM)
 #  undef HAVE_USBDEV
 #endif
 
@@ -207,10 +207,8 @@ int sam_hsmci_initialize(void);
  *
  ************************************************************************************/
 
-#ifdef HAVE_HSMCI
+#if defined(HAVE_HSMCI) && defined(CONFIG_MMCSD_HAVECARDDETECT)
 bool sam_cardinserted(int slotno);
-#else
-#  define sam_cardinserted(slotno) (false)
 #endif
 
 /************************************************************************************
diff --git a/configs/sam4s-xplained-pro/src/sam_hsmci.c b/configs/sam4s-xplained-pro/src/sam_hsmci.c
index 3d0e279d59..635bc22a90 100644
--- a/configs/sam4s-xplained-pro/src/sam_hsmci.c
+++ b/configs/sam4s-xplained-pro/src/sam_hsmci.c
@@ -83,14 +83,18 @@ static struct sam_hsmci_state_s g_hsmci;
  ****************************************************************************/
 
 /****************************************************************************
- * Name: sam_hsmci_cardetect
+ * Name: sam_hsmci_cardetect_int
  *
  * Description:
  *   Card detect interrupt handler
  *
+ * TODO: Any way to automatically moun/unmount filesystem based on card
+ * detect status?  Yes... send a message or signal to an application.
+ *
  ****************************************************************************/
 
-static int sam_hsmci_cardetect(int irq, void *regs)
+#ifdef CONFIG_MMCSD_HAVECARDDETECT
+static int sam_hsmci_cardetect_int(int irq, void *regs)
 {
   bool inserted;
 
@@ -100,7 +104,7 @@ static int sam_hsmci_cardetect(int irq, void *regs)
 
   /* Has the card detect state changed? */
 
-  if (inserted == g_hsmci.inserted)
+  if (inserted != g_hsmci.inserted)
     {
       /* Yes... remember that new state and inform the HSMCI driver */
 
@@ -113,6 +117,7 @@ static int sam_hsmci_cardetect(int irq, void *regs)
 
    return OK;
 }
+#endif
 
 /****************************************************************************
  * Public Functions
@@ -135,10 +140,6 @@ int sam_hsmci_initialize(void)
 
   if (!g_hsmci.initialized)
     {
-      /* Initialize card-detect GPIO.  There is no write-protection GPIO. */
-
-      sam_configgpio(GPIO_MCI_CD);
-
       /* Mount the SDIO-based MMC/SD block driver */
       /* First, get an instance of the SDIO interface */
 
@@ -158,14 +159,21 @@ int sam_hsmci_initialize(void)
           return ret;
         }
 
+#ifdef CONFIG_MMCSD_HAVECARDDETECT
+      /* Initialize card-detect GPIO.  There is no write-protection GPIO. */
+
+      sam_configgpio(GPIO_MCI_CD);
+
       /* Configure card detect interrupts */
 
       sam_gpioirq(GPIO_MCI_CD);
-      (void)irq_attach(MCI_CD_IRQ, sam_hsmci_cardetect);
-
+      (void)irq_attach(MCI_CD_IRQ, sam_hsmci_cardetect_int);
+      g_hsmci.inserted = sam_cardinserted(0);
+#else
+      g_hsmci.inserted = true; /* An assumption? */
+#endif
       /* Then inform the HSMCI driver if there is or is not a card in the slot. */
 
-      g_hsmci.inserted = sam_cardinserted(0);
       sdio_mediachange(g_hsmci.hsmci, g_hsmci.inserted);
 
       /* Now we are initialized */
@@ -174,7 +182,9 @@ int sam_hsmci_initialize(void)
 
       /* Enable card detect interrupts */
 
+#ifdef CONFIG_MMCSD_HAVECARDDETECT
       sam_gpioirqenable(MCI_CD_IRQ);
+#endif
     }
 
   return OK;
@@ -188,6 +198,7 @@ int sam_hsmci_initialize(void)
  *
  ****************************************************************************/
 
+#ifdef CONFIG_MMCSD_HAVECARDDETECT
 bool sam_cardinserted(int slotno)
 {
   bool removed;
@@ -199,6 +210,7 @@ bool sam_cardinserted(int slotno)
 
   return !removed;
 }
+#endif
 
 /****************************************************************************
  * Name: sam_writeprotected
diff --git a/configs/sam4s-xplained-pro/src/sam_nsh.c b/configs/sam4s-xplained-pro/src/sam_nsh.c
index 60b1aee82e..8802d7f76d 100644
--- a/configs/sam4s-xplained-pro/src/sam_nsh.c
+++ b/configs/sam4s-xplained-pro/src/sam_nsh.c
@@ -101,10 +101,21 @@
 
 int nsh_archinitialize(void)
 {
-#if defined(HAVE_HSMCI) || defined (HAVE_PROC) || defined(HAVE_USBMONITOR)
+#if defined (HAVE_USBDEV) || defined(HAVE_HSMCI) || defined (HAVE_PROC) || \
+    defined(HAVE_USBMONITOR)
   int ret;
 #endif
 
+#ifdef HAVE_USBDEV
+  message("Registering CDC/ACM serial driver\n");
+  ret = cdcacm_initialize(CONFIG_CDCACM_DEVMINOR, NULL);
+  if (ret < 0)
+    {
+      message("ERROR: Failed to create the CDC/ACM serial device: %d\n", errno);
+      return ret;
+    }
+#endif
+
 #ifdef HAVE_HSMCI
   /* Initialize the HSMCI driver */
 
@@ -123,10 +134,26 @@ int nsh_archinitialize(void)
   message("Mounting procfs to /proc\n");
   ret = mount(NULL, "/proc", "procfs", 0, NULL);
   if (ret < 0)
-  {
-    message("ERROR: Failed to mount the PROC filesystem: %d\n", errno);
-    return ret;
-  }
+    {
+      message("ERROR: Failed to mount the PROC filesystem: %d\n", errno);
+      return ret;
+    }
+#endif
+
+#if HAVE_HSMCI
+  message("Mounting /dev/mmcsd0 to /fat\n");
+  ret = mount("/dev/mmcsd0", "/fat", "vfat", 0, NULL);
+  if (ret < 0)
+    {
+      message("ERROR: Failed to mount the FAT filesystem: %d\n", errno);
+      return ret;
+    }
+#endif
+
+#ifdef CONFIG_TIMER
+  /* Registers the timer driver and starts an async interrupt. */
+
+  up_timerinitialize();
 #endif
 
 #ifdef HAVE_USBMONITOR
@@ -141,19 +168,5 @@ int nsh_archinitialize(void)
     }
 #endif
 
-  message("Mounting /dev/mmcsd0 to /fat\n");
-  ret = mount("/dev/mmcsd0", "/fat", "vfat", 0, NULL);
-  if (ret < 0)
-  {
-    message("ERROR: Failed to mount the FAT filesystem: %d\n", errno);
-    return ret;
-  }
-
-#ifdef CONFIG_TIMER
-  /* Registers the timer driver and starts an async interrupt. */
-
-  up_timerinitialize();
-#endif
-
   return OK;
 }
diff --git a/configs/sam4s-xplained-pro/src/sam_wdt.c b/configs/sam4s-xplained-pro/src/sam_wdt.c
index e78a12023f..a54d447010 100644
--- a/configs/sam4s-xplained-pro/src/sam_wdt.c
+++ b/configs/sam4s-xplained-pro/src/sam_wdt.c
@@ -61,7 +61,7 @@
  * Definitions
  ************************************************************************************/
 /* Configuration *******************************************************************/
-/* Wathdog hardware should be enabled */
+/* Watchdog hardware should be enabled */
 
 #if !defined(CONFIG_SAM34_WDT)
 #  warning "CONFIG_SAM34_WDT must be defined"
@@ -77,6 +77,10 @@
 #  endif
 #endif
 
+#if (CONFIG_WDT_THREAD_INTERVAL < CONFIG_WDT_MINTIME)
+#  error "WDT_THREAD_INTERVAL must be greater than or equal to WDT_MINTIME"
+#endif
+
 /* Debug ***************************************************************************/
 /* Non-standard debug that may be enabled just for testing the watchdog timer */
 
@@ -109,10 +113,8 @@
  * Public Functions
  ************************************************************************************/
 
+/* Watchdog kicker task */
 
-/*
-Watchdog kicker task
-*/
 #if defined(CONFIG_WDT_THREAD)
 static int wdog_daemon(int argc, char *argv[])
 {
@@ -172,7 +174,6 @@ errout:
 
 int up_wdginitialize(void)
 {
-
 #if (defined(CONFIG_SAM34_WDT) && !defined(CONFIG_WDT_DISABLE_ON_RESET))
   int fd;
   int ret;