XRT75R12 Datasheet, PDF (49/89 Pages) Exar Corporation – TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH JITTER ATTENUATOR

PRELIMINARY
TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH JITTER ATTENUATOR
XRT75R12
REV. P1.0.2
7.1 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 13. The microprocessor interface can be configured to operate in Asynchronous mode
or Synchronous mode.
PIN NAME
Pmode
D[7:0]
Addr[7:0]
CS
RD
WR
RDY
INT
RESET
TABLE 13: XRT75R12 MICROPROCESSOR INTERFACE SIGNALS
TYPE
DESCRIPTION
I Microprocessor Interface Mode Select Input pin
This pin is used to specify the microprocessor interface mode.
I/O Bi-Directional Data Bus for register "Read" or "Write" Operations.
I Eight-Bit Address Bus Inputs
The XRT75R12 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.
I Chip Select Input
This active low signal selects the microprocessor interface of the XRT75R12 LIU and enables
Read/Write operations with the on-chip register locations.
I Read Signal This active low input functions as the read signal from the local µP. 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.
I Write Signal This active low input functions as the write signal from the local µP. 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.
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.
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.
I Reset Input This active low input pin is used to Reset the LIU.
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