XRT74L73 Datasheet, PDF (41/488 Pages) Exar Corporation – 3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER

PRELIMINARY
PIN DESCRIPTION
PIN#
NAME
AE23
RxUPrty/
RxPPrty
AD18
RxUSoC/
RxPSOP
XRT74L73
3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
REV. P1.0.1
TYPE
O
O
DESCRIPTION
Receive UTOPIA Interface - Parity Output pin/Receive POS-PHY Interface -
Parity Output:
The exact function of this output pin depends upon whether the XRT74L73
device has been configured to operate in the ATM UNI or the PPP Modes.
ATM UNI Mode - RxUPrty
The Receive UTOPIA interface block will compute the odd-parity value of each
byte (or word) that it will place in the Receive UTOPIA Data Bus. This odd-parity
value will be output on this pin, while the corresponding byte (or word) is present
on the Receive UTOPIA Data Bus.
PPP Mode - RxPPrty
The Receive POS-PHY Interface block will compute the odd-parity value of each
byte (or word) that it will place in the Receive POS-PHY Data Bus. This odd par-
ity value will be output on this pin, which the corresponding byte (or word) is
present on the Receive POS-PHY Data Bus.
Receive UTOPIA Interface - Start of Cell Indicator/Receive POS-PHY Inter-
face - Start of Packet Indicator:
The exact function of this output pin depends upon whether the XRT74L73
device has been configured to operate in the ATM UNI or in the PPP Mode.
ATM UNI Mode - RxUSoC
This output pin allows the ATM Layer Processor to determine the boundaries of
the ATM cells that are output via the Receive UTOPIA Data bus. The Receive
UTOPIA Interface block will assert this signal when the first byte (or word) of a
new cell is present on the Receive UTOPIA Data Bus; RxUData[15:0].
PPP Mode - RxPSOP
This output pin allows the Link Layer Processor to determine the boundaries of
the PPP packets that are output via the Receive POS-PHY Data Bus. The
Receive POS-PHY Interface block will assert this signal when the first byte (or
word) of a new packet is present on the Receive POS-PHY Data Bus, RxP-
Data[15:0].
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