
Slow AMBA Peripherals
13-6
GMS30C7201 Data Sheet
NRI
In
RING signal
from AFE
Ring Indicator. When LOW, this indicates that a telephone
ring signal has been received by the MODEM or data set.
The
NRI
signal is a MODEM status input whose condition
can be tested by the CPU reading bit 6 (RI) of the MODEM
Status Register. Bit 6 is the complement of the
NRI
signal.
Bit 2 (TERI) of the MODEM Status Register indicates
whether the
NRI
input signal has changed from a LOW to a
HIGH state since the previous reading of the MODEM Status
Register.
Note: Whenever the RI bit of the MODEM Status Register
changes from a HIGH to a LOW state, an interrupt is
generated if the MODEM Status interrupt is enabled.
The
NRI
input from the external PAD is not provided.
To use this signal, you should set up the UART control
register of the AFE interface. For further information, refer to
13.9 Analog Front End, AFE (CODEC Interface)
on page
13-56.
NDTR
Out
External
Data Terminal Ready. When LOW, this informs the MODEM
or data set that the UART is ready to establish
communication link.
The NDTR output signal can be set to an active LOW by
programming bit 0 (DTR) of the MODEM Control Register to
HIGH level. A Master Reset operation sets this signal to its
inactive (HIGH) state. Loop mode operation holds this signal
in its inactive state.
NRTS
Out
External
When LOW, this informs the MODEM or data set that the
UART is ready to exchange data. The NRTS output signal
can be set to an active LOW by programming bit 1 (RTS) of
the MODEM Control Register. A Master Reset operation
sets this signal to its inactive (HIGH) state. Loop mode
operation holds this signal in its inactive state.
SOUT
Out
External
Serial Output. Composite serial data output to the
communications link (peripheral, MODEM or data set). The
SOUT
signal is set to the Marking (logic 1) state upon a
Master Reset operation.
Name
Type
Source/
Destination
Description
Table 13-2: Signal descriptions (Continued)