![](http://datasheet.mmic.net.cn/330000/PM7325_datasheet_16444376/PM7325_411.png)
S/UNI-ATLAS-3200 Telecom Standard Product Data Sheet
Preliminary
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990553, Issue 4
411
Figure 40 shows the RxLink I/O datapath signals for UTOPIA back to back transfer. Two cells
are shown being transferred from the same PHY address (PHY 8) with a dead cycle in between.
In order for full bandwidth support, RLU_CLAV must be asserted at least 8 clock cycles before
the end of the current transfer. See cycle 2. Note also that the RxLink squelches RLU_CLAV up
to RLU_RSOC+1 cycles if the phyid being serviced is identical to the one being polled. This is
to guarantee that the RLU_CLAV sent to the RxLink is not for the current cell being serviced, but
for the next cell transfer.
S/UNI-ATLAS-3200 always reselects the PHY by temporarily deasserting RLU_RDENB
between cell transfers.
RxPhy UTOPIA Timing
In the ingress direction the S/UNI-ATLAS-3200 output cell/packet interface acts as a Receive
PHY layer device, and the downstream device acts as an ATM Layer device, for the purposes of
UTOPIA Level 3 cell transfer.
Figure 41 RxPhy UTOPIA Cell Transfer
1
2
3
4
5
6
7
8
9
10
11
PHY07
PHY08
PHY09
PHY00
PHY02
PHY03
PHY04
D12
D11
D10
D9
PHY05
PHY06
PHY06
H1
D0
D1
D2
D3
PHY08
PHY07
PHY06
RPU_CLK
RPU_ADDR[5:0]
RPU_CLAV
RPU_RDENB
RPU_DAT[31:0]
RPU_SOC
RPU_PAR
The S/UNI-ATLAS-3200 UTOPIA Receive PHY Interface is controlled by the attached ATM
Layer device. Figure 41 shows the ATM layer polling the S/UNI-ATLAS-3200 device with the
address bus in order to gather cell available status. The S/UNI-ATLAS-3200 will assert
RPU_CLAV only when it can transfer an entire cell. The ATM Layer device will read the cell by
asserting the RPU_RDENB in response to a Receive Cell Available (RPU_CLAV) signal from the
S/UNI-ATLAS-3200 device. Figure 41 shows that PHY08 is engaged for transfer with the
selection cycle in clock number 4. PHY08 has two clocks to respond and does so with data in
cycle 6.
The RxPhy is capable of appearing as a single-PHY device, removing the need for polling. In
this case the RxPHY will use an internal calendar to determine the order in which the PHY
queues are serviced. Single-PHY operation is controlled via the Servicing Override bit in the
RxP Configuration register.