UART/IrDA Control and Status Registers
12-70
The enhanced feature register (EFR) enables or disables enhanced features,
most of which only apply to UART mode. But EFR[4] enables write accesses
to FCR[5:4], the TX trigger level, which is also used in SIR mode.
Table 12–59. Enhanced Feature Register (EFR)
Bit
Name
Value
Function
R/W
Reset
Value
7
AUTO_CTS_EN
Automatic CTS enable bit
R/W
0
0
Normal operation
1
Automatic CTS flow control is enabled; that
is, transmission is halted when the CTS pin
is high (inactive).
6
AUTO_RTS_EN
Automatic RTS enable bit
R/W
0
0
Normal operation
1
Automatic RTS flow control is enabled; that
is, the RTS pin goes high (inactive) when
the receiver FIFO HALT trigger level,
TCR3:0, is reached, and goes low (active)
when the receiver FIFO restore
transmission trigger level is reached.
5
SPECIAL_CHAR_
DETECT
0
Normal operation
R/W
0
1
Special character detect enable bit.
Received data is compared with XOFF2
data. If a match occurs, the received data is
transferred to FIFO and IIR bit 4 is set to 1
to indicate a special character has been
detected.
4
ENHANCED_EN
Enhanced functions write enable bit.
R/W
0
0
Disables writing to IER bits 4 - 7, FCR bits
4 - 5, and MCR bits 5 - 7
1
Enables writing to IER bits 4 - 7, FCR bits
4 - 5, and MCR bits 5 - 7
3–0
SW_FLOW_CONTROL
Combinations of software flow control can
be selected by programming bits 3:0. See
Table 12–60.
R/W
0