
xr
XRT94L33
3-CHANNEL DS3/E3/STS-1 TO STS-3/STM-1 MAPPER IC DATA SHEET
Rev.1.2.0.
449
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
UTOPIA
Level 3
Disable
Multi-PHY
Polling
Enable
Back to
Back
Polling
Enable
Direct
Status
Indication
Enable
Receive UTOPIA/POS-
PHY Data Bus Width
Cell Size[1:0]
R/W
1
0
1
X
Note:
This configuration setting does not apply to the Transmit UTOPIA Interface block. Therefore, the user will also
need to configure the Transmit UTOPIA Interface block into the Single-PHY Mode, as described in Section _.
In Single-PHY Mode operation, the ATM Layer Processor is pumping data into and receiving data from only
one PHY-Layer device, as depicted below in Figure 114
Figure 114 Simple Illustration of Single - PHY Mode Operation
XRT95L34
ATM Switch
(ATM Layer Device)
TxUData[15:0]
RxUData[15:0]
TxUClav
TxLData_p
TxLData_n
RxLData_p
TxFlow Control Input
To/From
Optical
Transceiver
RxUClav
TxUSoC
TxUEnB*
TxUPrty
TxUClk
RxUClk
RxUSoC
RxUEnB*
RxUPrty
RxFlow Control Input
Rx Start of Cell Input
Tx Start of Cell Output
Rx Read Output Enable Signal
Tx Write Enable Output
Rx Utopia Data Bus Parity
Tx Utopia Data Bus Parity
Rx FIFO Clock Signal
Tx FIFO Clock Signal
Rx ATM Cell Data
Tx ATM Cell Data
This section presents a detailed description of the Receive UTOPIA Interface block operating in the “Single-
PHY” Mode. A description of the Transmit UTOPIA Interface block operating in the “Single-PHY” Mode is
presented in Section _. Whenever the Receive UTOPIA Interface block has been configured to operate in the
Single-PHY Mode, and whenever the ATM Layer Processor wishes to read out one or a series of ATM cells
from the Receive UTOPIA Interface block, it must do the following.
1. Check the level of the RxUClav pin
If the RxUClav pin is “high” then the RxFIFO contains some ATM cell data that needs to be read by the ATM
Layer processor. In this case, the ATM Layer processor should begin to read the cell data from the Receive
UTOPIA Interface block. However, if the RxUClav pin is “low”, then the RxFIFO does not contain any cell
data, that can be read. In this case, the ATM Layer processor should wait until RxUClav toggles “high” before
attempting to read any more cell data from the “Receive UTOPIA Interface block”.