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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
373
Register 0x2C6: Bypass SDQ Cells and Packets Count
This register is used to read the count of the number of packets on the FIFO specified in the
Bypass SDQ Address register. The count reflects the write-side perspective, and will not react
immediately to reads. The counts are latched when the S/UNI-ATLAS-3200 Identity / Load
Counts Register is written to, or when any of the Bypass SDQ Count registers are written to.
While the transfer is in progress, the TIP bit is asserted in the Bypass SDQ Control Register and
S/UNI-ATLAS-3200 Identity / Load Counts Register, and remains high for the interval of the
update. TIP goes low once the counts are valid. Once TIP goes low, the count for the PHY
specified in the Bypass SDQ Address register will be placed in this register.
The recommended sequence for using this register is:
1.
Program the desired PHYID in the Bypass SDQ Address Register. Typically this would be
done while setting RWB = 1.
2.
Execute a write to this register
3.
Poll TIP in the Bypass SDQ Control Register until it becomes 0.
4.
Read the value in this register.
Bit
Type
Function
Default
31:12
Unused
X
11:0
R
COUNT[11:0]
0
COUNT[11:0]
This read-only field holds the last sampled count for the FIFO requested by PHYID[5:0] in
the FIFO indirect address register, at the time the transfer was initiated. Since each FIFO can
hold up to 3072 POS packets or 192 ATM cells, this count does not saturate or roll over.