![](http://datasheet.mmic.net.cn/330000/PM7325_datasheet_16444376/PM7325_407.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
407
Figure 36 TxLink POS-PHY Logical Timing
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
D15
P1
D4
P2
D5
D1
D2
P0
P1
P2
P4
P0
P1
P4
P1
P2
P4
P0
P1
P2
P2
P4
P4
P2
P4
P0
P0
P1
0
3
0
D14
P1
P1
D32
D33
3
D0
D3
P2
P2
3
0
P1
TLP_CLK
TLP_SX
TLP_SOP
TLP_EOP
TLP_ERR
TLP_ENB
TLP_DAT[31:0]
TLP_PAR
TLP_MOD[1:0]
TLP_STPA
TLP_ADDR[5:0]
TLP_PTPA
Figure 36 is an example of polling and transmission to a multi-port PHY device with several
channels. The PHY layer device indicates that a FIFO is not full by asserting TLP_PTPA when it
is polled by the S/UNI-ATLAS-3200. Polling is accomplished with the TLP_ADDR[5:0] signal.
After selection, packet available status is indicated by asserting the selected transmit packet
available signal TLP_STPA. TLP_STPA remains asserted while the PHY is selected and until the
transmit FIFO is almost full. The S/UNI-ATLAS-3200 will halt data transfer three clocks after
TLP_STPA is driven low on the bus, if the USE_STPA register bit is logic 1. The S/UNI-
ATLAS-3200 will then select the next PHYID in the calendar which has a positive PTPA
response and for which data is available in the S/UNI-ATLAS-3200.
The S/UNI-ATLAS-3200 will transmit packets in 16 word bursts. In cycle 1 and 2, a 16 word
burst is completing for a packet. In cycle 3, PHY P1 is selected for transfer and the PHY device
indicates the selected PHY is nearly full by deasserting TLP_STPA in cycle 6. The ATM Layer
device halts data transfer in cycle 9. PHY P1 is again polled in cycle 9, and the PHY device
indicates that it has space for additional data. The ATM layer device selects PHY P1 in cycle 14,
and continues the packet transfer.