diff --git a/configs/sam3u-ek/ostest/defconfig b/configs/sam3u-ek/ostest/defconfig
index ff18be8f1028eb9f9ed2aacf5f67aa9df333fe28..cc19b2cd935ff88f9ee7edb0933baf5895499d3a 100755
--- a/configs/sam3u-ek/ostest/defconfig
+++ b/configs/sam3u-ek/ostest/defconfig
@@ -100,10 +100,20 @@ CONFIG_SAM3U_BUILDROOT=y
 #
 #  Individual subsystems can be enabled:
 #
-CONFIG_SAM3U_USART0=y
-CONFIG_SAM3U_USART1=y
-CONFIG_SAM3U_USART2=y
-CONFIG_SAM3U_USART3=y
+CONFIG_SAM3U_USART=y
+CONFIG_SAM3U_USART0=n
+CONFIG_SAM3U_USART1=n
+CONFIG_SAM3U_USART2=n
+CONFIG_SAM3U_USART3=n
+
+#
+# Some subsystems can be configured to operate in different ways..
+# The drivers need to know how to configure the subsystem.
+#
+CONFIG_USART0_ISUART=y
+CONFIG_USART1_ISUART=y
+CONFIG_USART2_ISUART=y
+CONFIG_USART3_ISUART=y
 
 #
 # SAM3U specific serial device driver settings
@@ -119,36 +129,43 @@ CONFIG_SAM3U_USART3=y
 # CONFIG_USARTn_PARTIY - 0=no parity, 1=odd parity, 2=even parity
 # CONFIG_USARTn_2STOP - Two stop bits
 #
-CONFIG_USART0_SERIAL_CONSOLE=Y
+CONFIG_USART_SERIAL_CONSOLE=Y
+CONFIG_USART0_SERIAL_CONSOLE=n
 CONFIG_USART1_SERIAL_CONSOLE=n
 CONFIG_USART2_SERIAL_CONSOLE=n
 CONFIG_USART3_SERIAL_CONSOLE=n
 
+CONFIG_USART_TXBUFSIZE=256
 CONFIG_USART0_TXBUFSIZE=256
 CONFIG_USART1_TXBUFSIZE=256
 CONFIG_USART2_TXBUFSIZE=256
 CONFIG_USART3_TXBUFSIZE=256
 
+CONFIG_USART_RXBUFSIZE=256
 CONFIG_USART0_RXBUFSIZE=256
 CONFIG_USART1_RXBUFSIZE=256
 CONFIG_USART2_RXBUFSIZE=256
 CONFIG_USART3_RXBUFSIZE=256
 
+CONFIG_USART_BAUD=115200
 CONFIG_USART0_BAUD=115200
 CONFIG_USART1_BAUD=115200
 CONFIG_USART2_BAUD=115200
 CONFIG_USART3_BAUD=115200
 
+CONFIG_USART_BITS=8
 CONFIG_USART0_BITS=8
 CONFIG_USART1_BITS=8
 CONFIG_USART2_BITS=8
 CONFIG_USART3_BITS=8
 
+CONFIG_USART_PARITY=0
 CONFIG_USART0_PARITY=0
 CONFIG_USART1_PARITY=0
 CONFIG_USART2_PARITY=0
 CONFIG_USART3_PARITY=0
 
+CONFIG_USART_2STOP=0
 CONFIG_USART0_2STOP=0
 CONFIG_USART1_2STOP=0
 CONFIG_USART2_2STOP=0