UART/IrDA Control and Status Registers
12-65
UART Devices
The modem status register (MSR) provides information about the current state
of the control lines from the modem, data set, or peripheral device to the host
(MPU or DSP). It also indicates when a control input from the modem changes
state.
Table 12–54. Modem Status Register (MSR)
Bit
Name
Function
R/W
Reset
Value
7–6
RESERVED
Reserved
R
5
NDSR_STS
This bit is the complement of the DSR input.
In loopback mode, it is equivalent to MCR0.
R
Input
signal
4
NCTS_STS
This bit is the complement of the CTS input.
In loopback mode, it is equivalent to MCR1.
R
Input
signal
3–2
RESERVED
Reserved
R
0
1
DSR_STS
1: Indicates that DSR input (or MCR0 in loopback)
has changed state. Cleared on a read.
R
0
0
CTS_STS
1: Indicates that CTS input (or MCR1 in loopback)
has changed state. Cleared on a read.
R
0