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+The USART Synchronous Driver
+============================
+
+The universal synchronous and asynchronous receiver and transmitter
+(USART) is usually used to transfer data from one device to the other.
+
+User can set action for flow control pins by function usart_set_flow_control,
+if the flow control is enabled. All the available states are defined in union
+usart_flow_control_state.
+
+Note that user can set state of flow control pins only if automatic support of
+the flow control is not supported by the hardware.
+
+Features
+--------
+
+* Initialization/de-initialization
+* Enabling/disabling
+* Control of the following settings:
+
+  * Baudrate
+  * UART or USRT communication mode
+  * Character size
+  * Data order
+  * Flow control
+* Data transfer: transmission, reception
+
+Applications
+------------
+
+They are commonly used in a terminal application or low-speed communication
+between devices.
+
+Dependencies
+------------
+
+USART capable hardware.
+
+Concurrency
+-----------
+
+Write buffer should not be changed while data is being sent.
+
+
+Limitations
+-----------
+
+* The driver does not support 9-bit character size.
+* The "USART with ISO7816" mode can be only used in ISO7816 capable devices. 
+  And the SCK pin can't be set directly. Application can use a GCLK output PIN
+  to generate SCK. For example to communicate with a SMARTCARD with ISO7816
+  (F = 372 ; D = 1), and baudrate=9600, the SCK pin output frequency should be
+  config as 372*9600=3571200Hz. More information can be refer to ISO7816 Specification.
+
+Known issues and workarounds
+----------------------------
+
+N/A