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PRELIMINARY
DS3 UNI FOR ATM
XRT7245
REV. 1.03
153
6.1.2.3.3
The local
μ
P has the ability to poll and monitor the
status of the Tx FIFO via the Transmit UTOPIA FIFO
Monitoring the Tx FIFO Status
Status Register (Address = 71h). The bit format of
this register is presented below.
The following tables define the values for Bits 1 and 0
and the corresponding meaning.
6.1.2.4
UTOPIA Modes of Operation (Single
PHY and Multi-PHY operation)
The UNI chip can support both Single-PHY and
Multi-PHY operation. Each of these operating modes
are discussed below.
6.1.2.4.1
The UNI chip will be operating in the Multi-PHY mode
upon power up or reset. Therefore, the user must write
a “1” to Bit 4 within the UTOPIA Configuration register
(Address = 6Ah) in order to configure the UNI into the
Single-PHY Mode.
Single PHY Operation
Writing a ‘1’ to this bit-field configures the UNI to op-
erate in the Single-PHY Mode. Writing a ‘0’ config-
ures the UNI to operate in the Multi-PHY Mode.
In Single-PHY operation, the ATM layer processor is
pumping data into and receiving data from only one
UNI device, as depicted in Figure 35.
Transmit UTOPIA FIFO Status Register (Address = 71h)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Unused
TxFIFO Full
TxFIFO Empty
RO
RO
RO
RO
RO
RO
RO
RO
TxFIFO Full
T
X
FIFO F
ULL
(B
IT
1)
M
EANING
0
Tx FIFO is full, the ATM Layer processor risks causing an overrun if it writes to the TxFIFO now.
1
Tx FIFO is not full.
Tx FIFO Empty
T
X
FIFO E
MPTY
(B
IT
0)
M
EANING
0
Tx FIFO is not empty
1
Tx FIFO is empty. The Tx Cell Processor is currently generating IDLE cells
UTOPIA Configuration Register: Address = 6Ah
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Unused
Handshake Mode
S-PHY/M-PHY*
CellOf52 Bytes
TFIFODepth[1, 0]
UtWidth16
RO
R/W
R/W
R/W
R/W
R/W