
XRT7245
DS3 UNI FOR ATM
á
PRELIMINARY
REV. 1.03
38
3.0 MICROPROCESSOR INTERFACE
SECTION AND ON-CHIP
PROGRAMMABLE REGISTERS
The Microprocessor Interface section supports com-
munication between the “l(fā)ocal” microprocessor (μP)
and the UNI device. In particular, the Microprocessor
Interface section supports the following operations
between the local microprocessor and the UNI.
The writing of configuration data into the UNI on-
chip (addressable) registers.
The writing of “outbound” OAM cell data into the
“Transmit OAM Cell” Buffer (within the UNI).
The writing of an “outbound” PMDL (Path Mainte-
nance Data Link) message into the “Transmit LAPD
Message” buffer (within the UNI).
The UNI IC’s generation of an Interrupt Request to
the μP
The μP’s servicing of the interrupt request from the
UNI.
The monitoring of the UNI system’s “health” by
periodically reading the on-chip Performance Monitor
registers.
The reading of an “inbound” OAM cell data from
the “Receive OAM Cell” buffer (within the UNI).
The reading of an “inbound” PMDL Message from
the “Receive LAPD” Buffer (within the UNI).
Each of these operations (between the local micropro-
cessor and the UNI) will be discussed in some detail,
throughout this data sheet
Figure 7 presents a simple block diagram of the
Microprocessor Interface Section, within the UNI
device.
3.1
The Microprocessor Interface Signals
The UNI may be configured into a wide variety of
different operating modes and have its performance
monitored by software through a standard (local
“housekeeping”) microprocessor, using data, address
and control signals.
Note:
This local “housekeeping” Microprocessor should
not be confused with the ATM Layer Processor that inter-
faces to the UNI via the Transmit and Receive UTOPIA
Interface Blocks.
The local μP configures the UNI (into a desired oper-
ating mode) by writing data into specific addressable,
on-chip “Read/Write” registers; or on-chip RAM. The
microprocessor interface provide the signals which are
required for a general purpose microprocessor to read
or write data into these registers. The Microprocessor
Interface also supports “polled” and interrupt driven
environments. These interface signals are described
below in Table 1, 2, and 3. The microprocessor inter-
face can be configured to operate in the “Motorola”
mode or in the “Intel” mode. When the Microprocessor
Interface is operating in the “Motorola” mode, then
some of the control signals function in a manner as
required by the Motorola 68000 family of micropro-
cessors. Likewise, when the Microprocessor Interface
is operating in the “Intel” Mode, then some of these
Control Signals function in a manner as required by
the Intel 80xx family of microprocessors.
Table 1 lists and describes those Microprocessor Inter-
face signals whose role is constant across the two
F
IGURE
7. S
IMPLE
B
LOCK
D
IAGRAM
OF
M
ICROPROCESSOR
I
NTERFACE
BLOCK
OF
UNI
A[8:0]
WrB_RW
RdB_DS
CSB*
ALE_AS
Reset
IntB*
D[15:0]
Width16
MOTO
Rdy_Dtck
Microprocessor Interface
and
Programmable Registers