XRT75R12D_06 Datasheet, PDF (50/134 Pages) Exar Corporation – TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET

XRT75R12D
TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER REV. 1.0.1
7.0 MICROPROCESSOR INTERFACE BLOCK
The Microprocessor Interface section supports communication between the local microprocessor (µP) and the
LIU. The XRT75R12D supports a parallel interface asynchronously or synchronously timed to the LIU. The
microprocessor interface is selected by the state of the Pmode input pin. Selecting the microprocessor inter-
face mode is shown in Table 13.
TABLE 13: SELECTING THE MICROPROCESSOR INTERFACE MODE
PMODE
MICROPROCESSOR MODE
"Low"
Asynchronous Mode
"High"
Synchronous Mode
The local µP configures the LIU by writing data into specific addressable, on-chip Read/Write registers. The
µP provides the signals which are required for a general purpose microprocessor to read or write data into
these registers. The µP also supports polled and interrupt driven environments. A simplified block diagram of
the microprocessor is shown in Figure 34.
FIGURE 34. SIMPLIFIED BLOCK DIAGRAM OF THE MICROPROCESSOR INTERFACE BLOCK
CS
WR
RD
Addr[7:0]
D[7:0]
PCLK
Pmode
RESET
RDY
INT
Microprocessor
Interface
45