diff --git a/configs/stm3240g-eval/include/board.h b/configs/stm3240g-eval/include/board.h
index 56a75a56fa0..e3825551fd0 100755
--- a/configs/stm3240g-eval/include/board.h
+++ b/configs/stm3240g-eval/include/board.h
@@ -145,6 +145,16 @@
 
 #warning "Missing logic"
 
+/* Alternate function pin selections ************************************************/
+
+/* UART3:
+ * - PC11 is MicroSDCard_D3 & RS232/IrDA_RX (JP22 open)
+ * - PC10 is MicroSDCard_D2 & RSS232/IrDA_TX
+ */
+
+#define GPIO_USART3_RX GPIO_USART3_RX_2
+#define GPIO_USART3_TX GPIO_USART3_TX_2
+
 /************************************************************************************
  * Public Data
  ************************************************************************************/
diff --git a/configs/stm3240g-eval/ostest/defconfig b/configs/stm3240g-eval/ostest/defconfig
index bc8fcf94ffa..80a4ad45b05 100755
--- a/configs/stm3240g-eval/ostest/defconfig
+++ b/configs/stm3240g-eval/ostest/defconfig
@@ -149,7 +149,7 @@ CONFIG_STM32_WWDG=n
 CONFIG_STM32_SPI2=n
 CONFIG_STM32_SPI3=n
 CONFIG_STM32_USART2=n
-CONFIG_STM32_USART3=n
+CONFIG_STM32_USART3=y
 CONFIG_STM32_UART4=n
 CONFIG_STM32_UART5=n
 CONFIG_STM32_I2C1=n
@@ -162,7 +162,7 @@ CONFIG_STM32_DAC=n
 # APB2:
 CONFIG_STM32_TIM1=n
 CONFIG_STM32_TIM8=n
-CONFIG_STM32_USART1=y
+CONFIG_STM32_USART1=n
 CONFIG_STM32_USART6=n
 CONFIG_STM32_ADC1=n
 CONFIG_STM32_ADC2=n
@@ -193,23 +193,23 @@ CONFIG_STM32_TIM11=n
 # CONFIG_USARTn_PARTIY - 0=no parity, 1=odd parity, 2=even parity
 # CONFIG_USARTn_2STOP - Two stop bits
 #
-CONFIG_USART1_SERIAL_CONSOLE=y
+CONFIG_USART1_SERIAL_CONSOLE=n
 CONFIG_USART2_SERIAL_CONSOLE=n
-CONFIG_USART3_SERIAL_CONSOLE=n
+CONFIG_USART3_SERIAL_CONSOLE=y
 CONFIG_USART4_SERIAL_CONSOLE=n
 CONFIG_USART5_SERIAL_CONSOLE=n
 
-CONFIG_USART1_TXBUFSIZE=256
-CONFIG_USART2_TXBUFSIZE=256
-CONFIG_USART3_TXBUFSIZE=256
-CONFIG_USART4_TXBUFSIZE=256
-CONFIG_USART5_TXBUFSIZE=256
+CONFIG_USART1_TXBUFSIZE=128
+CONFIG_USART2_TXBUFSIZE=128
+CONFIG_USART3_TXBUFSIZE=128
+CONFIG_USART4_TXBUFSIZE=128
+CONFIG_USART5_TXBUFSIZE=128
 
-CONFIG_USART1_RXBUFSIZE=256
-CONFIG_USART2_RXBUFSIZE=256
-CONFIG_USART3_RXBUFSIZE=256
-CONFIG_USART4_RXBUFSIZE=256
-CONFIG_USART5_RXBUFSIZE=256
+CONFIG_USART1_RXBUFSIZE=128
+CONFIG_USART2_RXBUFSIZE=128
+CONFIG_USART3_RXBUFSIZE=128
+CONFIG_USART4_RXBUFSIZE=128
+CONFIG_USART5_RXBUFSIZE=128
 
 CONFIG_USART1_BAUD=115200
 CONFIG_USART2_BAUD=115200