S/UNI®-8x155 ASSP Telecom Standard Product Data Sheet
Released
Pin Name
Type
Pin
No.
Function
TCA
Output
N29
The UTOPIA transmit cell available (TCA) signal provides
status indication of when cell space is available in the
transmit FIFO.
TCA is used to poll the channel FIFOs to determine the
number of free ATM cell buffers that are in the FIFO. The
address sampled on TADR[2:0] will cause TCA to be
updated with the channel information on the following clock
cycle.
When TCA is high, the channel FIFO can accept at least one
more ATM cell. When TCA is low, the channel FIFO fill level
exceeds the threshold specified by the FIFODP[1:0] register.
Note that regardless of the threshold, a channel FIFO can
store 16 ATM cells.
TCA is updated on the rising edge of TFCLK.
PTPA
STPA
The POS-PHY polled transmit packet available (PTPA) signal
provides status indication of when cell space is available in
the transmit FIFO. The TADR[2:0] address is used to
determine which channel to report on PTPA.
When PTPA transitions high, it indicates that the transmit
FIFO has enough room to store a configurable number of
data bytes. When PTPA transitions low, it indicates that the
transmit FIFO is either full or near full. These thresholds are
specified in the TUL3 registers.
PTPA is updated on the rising edge of TFCLK.
Output
N28
The POS-PHY selected transmit packet available (STPA)
signal provides status indication of when cell space is
available in the transmit FIFO. The channel selected using
TSX is reported on STPA.
When STPA transitions high, it indicates that the transmit
FIFO has enough room to store a configurable number of
data bytes. When STPA transitions low, it indicates that the
transmit FIFO is either full or near full. These thresholds are
specified in the TUL3 registers.
STPA is updated on the rising edge of TFCLK.
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC- 2010299, Issue 2
51
PMC [ PMC-SIERRA, INC ]
