UART/Autobaud Control and Status Registers
12-26
Table 12–20. Supplementary Status Register (SSR)
Bit
Name
Value
Function
R/W
Reset
Value
7–2
–
Reserved
R
000000
1
RX_CTS_DSR_WAKE_
UP_STS
0
No falling edge event on RX, CTS and
DSR
R
0
1
A falling edge occurred on RX, CTS or
DSR.
0
TX_FIFO_FULL
0
TX FIFO not full
R
0
1
TX FIFO full
Note:
Bit 1 is reset only when SCR[4] is reset to 0.
The modem control register (MCR)[3:0] controls the interface with the modem,
data set, or peripheral device that is emulating the modem.
Table 12–21. Modem Control Register (MCR)
Bit
Name
Value
Function
R/W
Reset
Value
7
CLKSEL
0
No action
R/W
0
1
Divide clock input by 4
6
TCR_TLR
0
No action
R/W
0
1
Enables access to the TCR and TLR registers
5
XON_EN
0
Disable XON any function
R/W
0
1
Enable XON any function
4
LOOPBACK_EN
0
Normal operating mode
R/W
0
1
Enable local loop back mode (internal).
In this mode the MCR3:0 signals are looped
back into MSR7:4. The transmit output is
looped back to the receive input internally.
3
CD_STS_CH
0
In loopback mode, forces IRQ outputs to
inactive state
R/W
0
1
In loopback mode, forces IRQ outputs to
inactive state
Note:
Bits 5, 6, and 7 can be written only when EFR[4] = 1.