PM5357 Datasheet, PDF (49/432 Pages) PMC-Sierra, Inc – 622 Mbit/s ATM and Packet Over SONET Physical Layer Device

PRODUCTION
S/UNI-622-POS
DATASHEET
PMC-1980911
ISSUE 5
PMC-Sierra, Inc.
PM5357
S/UNI-622-POS
SATURN USER NETWORK INTERFACE (622-POS)
Pin Name
TCA
TPA
Type
Output
Pin
No.
L23
Function
The UTOPIA transmit cell available (TCA) signal
provides direct status indication of when cell space is
available in the transmit FIFO.
When set high, TCA indicates that the corresponding
transmit FIFO is not full and a complete cell may be
written. TCA is set low to either indicate that the
transmit FIFO is near full or that the transmit FIFO is
full. To reduce FIFO latency, the FIFO depth at which
TCA indicates "full" can be set to one, two, three or
four cells. Note that regardless of what fill level TCA
is set to indicate "full" at, the transmit cell processor
can store 4 complete cells.
In 16-bit Level 2 ATM mode, TCA will transition low
one TFCLK cycle after the payload word 19 or 23
(depending of the configuration in TXCP) is sampled
on the TDAT[15:0] bus.
In 8-bit Level 3 ATM mode, TCA will transition low on
the rising edge of TFCLK before the payload byte 45
is sampled on the TDAT[7:0] bus.
TCA is updated on the rising edge of TFCLK.
The POS-PHY transmit packet available (TPA) signal
provides direct status indication the fill status of the
transmit FIFO. Note that regardless of what fill level
TPA is set to indicate "full" at, the transmit packet
processor can store 256 bytes of data.
When TPA transitions high, it indicates that the
transmit FIFO has enough room to store a
configurable number of data bytes. This transition
level is selected in the TXFP registers.
When TPA transitions low, it indicates that the
transmit FIFO is either full or near full as specified by
the TXFP registers.
TPA is updated on the rising edge of TFCLK.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA INC., AND ITS CUSTOMERS’ INTERNAL USE
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