xr
XRT75L06D
REV. 1.0.4
SIX CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER
43
6.1
THE MICROPROCESSOR INTERFACE BLOCK SIGNALS
The LIU may be configured into different operating modes and have its performance monitored by software
through a standard microprocessor using data, address and control signals. These interface signals are de-
scribed below in
Table 12. The microprocessor interface can be configured to operate in Asynchronous mode
or Synchronous mode.
TABLE 12: XRT75L06D MICROPROCESSOR INTERFACE SIGNALS
PIN NAME
TYPE
DESCRIPTION
Pmode
I
Microprocessor Interface Mode Select Input pin
This pin is used to specify the microprocessor interface mode.
D[7:0]
I/O
Bi-Directional Data Bus for register "Read" or "Write" Operations.
Addr[7:0]
I
Eight-Bit Address Bus Inputs
The XRT75L06D LIU microprocessor interface uses a direct address bus. This address bus is
provided to permit the user to select an on-chip register for Read/Write access.
CS
I
Chip Select Input
This active low signal selects the microprocessor interface of the XRT75L06D LIU and
enables Read/Write operations with the on-chip register locations.
RD
I
Read Signal This active low input functions as the read signal from the local
P. When this
pin is pulled “Low” (if CS is “Low”) the LIU is informed that a read operation has been
requested and begins the process of the read cycle.
WR
I
Write Signal This active low input functions as the write signal from the local
P. When this
pin is pulled “Low” (if CS is “Low”) the LIU is informed that a write operation has been
requested and begins the process of the write cycle.
RDY
O
Ready Output This active low signal is provided by the LIU device. It indicates that the cur-
rent read or write cycle is complete, and the LIU is waiting for the next command.
INT
O
Interrupt Output This active low signal is provided by the LIU to alert the local mP that a
change in alarm status has occured. This pin is Reset Upon Read (RUR) once the alarm sta-
tus registers have been cleared.
RESET
I
Reset Input This active low input pin is used to Reset the LIU.