A transmission frame can be terminated in two ways:
- Frame-length method: Set the UART_MDR1[7]
FRAME_END_MODE bit to 0. The Host CPU writes the value of the frame length to
the UART_TXFLH and UART_TXFLL registers. The device automatically attaches end
flags to the frame when the number of bytes transmitted equals the value of the
frame length.
- Set-EOT bit method: Set the UART_MDR1[7]
FRAME_END_MODE bit to 1. The Host CPU writes 1 to the UART_ACREG[0] EOT bit just
before it writes the last byte to the TX FIFO. When the Host CPU writes the last
byte to the TX FIFO, the device internally sets the tag bit for that character
in the TX FIFO. As the TX state-machine reads data from the TX FIFO, it uses
this tag-bit information to attach end flags and correctly terminate the
frame.