XRT79L71_07 Datasheet, PDF (37/109 Pages) Exar Corporation – 1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC - HARDWARE

REV. 1.0.0
PIN #
B4
NAME
RxRED/
RxNib_3/
RxHDLCDat_3
XRT79L71
1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC - HARDWARE
TYPE
O
DESCRIPTION
Receive Section Red Alarm Indicator/Receive Nibble Interface Output pin -
Bit 3/Receive HDLC Controller Data Bus output pin - Bit 3:
The function of this output pin depends upon whether the XRT79L71 has been
configured to operate in the Clear-Channel Framer/Nibble-Parallel Mode, the
High-Speed HDLC Controller Mode, or in some other mode.
Clear-Channel Framer/Nibble-Parallel Mode - RxNib_3:
The XRT79L71 will output Received data from the remote terminal equipment
to the System-Side terminal equipment via this pin, along with RxNib_0 through
RxNib_2. This particular output pin functions as the LSB. The data at this pin is
updated on the rising edge of the RxClk output signal. Hence, the user's Sys-
tem-Side terminal equipment should sample this signal upon the falling edge of
RxClk.
High-Speed HDLC Controller Mode - Receive High-Speed HDLC Controller
Output Interface Block - Data Bus Output Pin #3 - RxHDLCDat_3:
This output pin along with RxHDLCDat_[7:4] and RxHDLCDat_[2:0] functions
as the Receive High-Speed HDLC Controller Output Interface byte wide output
data bus. The Receive High-Speed HDLC Controller Output Interface block will
output the contents of all HDLC frames and flag sequence octects via this out-
put data bus, upon the rising edge of the RxHDLCClk output signal. Hence, the
user's local terminal equipment should be designed/configured to sample this
data upon the falling edge of the RxHDLCClk output clock signal.
Other Modes - RxRED - RED Alarm/Defect Indicator Output pin:
The XRT79L71 will assert this output pin (e.g., toggle it "High") in order to indi-
cate that the Receive DS3/E3 Framer block is currently declaring at least one of
the following defect conditions.
• LOS - Loss of Signal Defect Condition
• OOF - Out of Frame Defect Condition
• AIS - Alarm Indication Signal Defect Condition.
The XRT79L71 will negate this output pin (e.g., toggle it "Low") anytime that the
Receive DS3/E3 Framer block is NOT currently declaring any of the above-
mentioned defect conditions.
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