S/UNI®-ATLAS-3200 Telecom Standard Product Data Sheet
Preliminary
Register 0x039: OBCIF Dropped Cells Counter
Bit
31:8
7:0
Type
Function
Unused
DCOUNT[7:0]
Default
X
X
R
This register provides a count of cells dropped by the OBCIF due toFIFO overflow. Overflow of
the OBCIF can only occur for Loopback cells, and cells routed to the BCIF via the VC_to_BCIF
function. RDI cells and Bwd PM cells will be delayed and sent later if the OBCIF is full, and
thus cannot be lost due to FIFO overflow. The OBCIF is drained at the lesser of the opposite-
direction Backward Cell Interface Pacing rate, and the capacity of the BCIF link (approximately
1.3 million cells per second).
DCOUNT[7:0]
A write to this register or the S/UNI-ATLAS-3200 Identity/Load Counts register loads this
register with the number of cells dropped by the OBCIF due to FIFO overflow since the last
such write, and resets the internal counter to zero. The update is done in such a fashion that
no events are missed if a counter reset and a dropped cell occur simultaneously. During this
transfer, the TIP bit in the S/UNI-ATLAS-3200 Identity/Load Counts register will be logic 1.
The contents of this register are valid when the TIP bit returns to logic 0; however, another
transfer should not be requested for at least 100ns after TIP returns to 0. If this register is not
polled regularly, the count value will saturate at 0xFF.
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990553, Issue 4
181
PMC [ PMC-SIERRA, INC ]
