Cirrus Logic EP93xx User Manual

Page 545

DS785UM1

14-23

UART1 With HDLC and Modem Control Signals

EP93xx User’s Guide

Address:

0x808C_0018 - Read Only

Default:

0x0000_0000

Definition:

UART Flag Register

Bit Descriptions:

RSVD:

Reserved. Unknown During Read.

TXFE:

Transmit FIFO Empty. The meaning of this bit depends on
the state of the FEN bit in the UART1LinCtrlHigh register.
If the FIFO is disabled, this bit is set when the transmit
holding register is empty. If the FIFO is enabled, the TXFE
bit is set when the transmit FIFO is empty.

RXFF:

Receive FIFO Full. The meaning of this bit depends on the
state of the FEN bit in the UART1LinCtrlHigh register. If
the FIFO is disabled, this bit is set when the receive
holding register is full. If the FIFO is enabled, the RXFF bit
is set when the receive FIFO is full.

TXFF:

Transmit FIFO Full. The meaning of this bit depends on
the state of the FEN bit in the UART1LinCtrlHigh register.
If the FIFO is disabled, this bit is set when the transmit
holding register is full. If the FIFO is enabled, the TXFF bit
is set when the transmit FIFO is full.

RXFE:

Receive FIFO Empty. The meaning of this bit depends on
the state of the FEN bit in the UART1LinCtrlHigh register.
If the FIFO is disabled, this bit is set when the receive
holding register is empty. If the FIFO is enabled, the RXFE
bit is set when the receive FIFO is empty.

BUSY:

UART Busy. If this bit is set to 1, the UART is busy
transmitting data. This bit remains set until the complete
byte, including all the stop bits, has been sent from the
shift register. This bit is set as soon as the transmit FIFO
becomes non-empty (regardless of whether the UART is
enabled or not).

DCD:

Data Carrier Detect status. This bit is the complement of
the UART data carrier detect (nUARTDCD) modem status
input. That is, the bit is 1 when the modem status input is
0.

DSR:

Data Set Ready status. This bit is the complement of the
UART data set ready (nUARTDSR) modem status input.
That is, the bit is 1 when the modem status input is 0.