The Universal Synchronous/Asynchronous Receiver/Transmitter (USART) interface is connected through three digital signals; RX, TX, and XCK. All pins are tri-stated until the interface is activated from the PC.
Both synchronous and asynchronous modes are supported. If operated in asynchronous mode, the correct baud rate setting must be supplied. The baud rate is flexible and is accurate up to 2Mbps. Supported parity settings are none, even, odd, mark, and space. Stop bit can be set to 1, 1.5, and 2 stop bits. It is possible to use a transfer size of 5-8 bits. If used in synchronous mode, a clock signal must be supplied by the target device.
In normal operation, DMA will automatically buffer incoming data transfers. It is also possible to enable timestamping to get a more accurate timing of incoming data. Note that the timestamping will add an overhead to each data transfer, and a lower maximal throughput and a longer required inter-byte delay is expected. For sending data to the target device DMA is always used.