XRT79L74 Datasheet, PDF (39/70 Pages) Exar Corporation – 4 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC

PRELIMINARY
4 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC
XRT79L74
REV. P1.0.0
PIN #
B16
E13
A9
NAME
RxUPrty/
RxPPrty
RxPEOP
RxPDVAL
TYPE
O
O
O
DESCRIPTION
Receive UTOPIA Interface - Parity Output pin/Receive POS-PHY Interface -
Parity Output:
The function of this output pin depends upon whether the XRT79L74 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-par-
ity 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 parity value will be output on this pin, which the corresponding byte (or
word) is present on the Receive POS-PHY Data Bus.
NOTE: This output pin will be in-active if the user has configured the XRT79L74
device to operate in either the Clear-Channel Framer or in the High-
Speed HDLC Controller Modes.
Receive POS-PHY Interface - End of Packet:
The XRT79L74 drives this output pin "High" whenever the last byte of a given
Packet is being output via the RxPData[15:0] data bus.
NOTES:
1. This output pin is only valid when the XRT79L74 is configured to
operate in the PPP Mode.
2. This output pin is only valid when the Receive POS-PHY Interface -
Read Enable Output pin.
Receive POS-PHY Interface Signal Valid Indicator:
This output signal indicates whether or not the Receive POS-PHY Interface sig-
nals (e.g., PRData[15:0], RxPSOP, RxPEOP, RxPPrty, RxPERR) are valid.
This output pin will be driven "High", when these signals are valid. Conversely,
this output pin will be driven "Low" when these signals are NOT valid.
NOTE: This output pin is only active if the XRT79L74 has been configured to
operate in the PPP Mode.
37