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1 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC
PRELIMINARY
XRT79L71
REV. P1.0.3
13
B9
TxOHInd/
TxPFrame/
TxHDLCDat_6/
I/O
Transmit Overhead Data Indicator Output/Transmit PLCP Frame Boundary
Indicator Output/Transmit HDLC Controller Data Bit 6 input pin:
The function of these input/output pins depends upon whether the XRT79L71
has been configured to operate in the Clear-Channel Framer Mode, the ATM/
PLCP Mode or the High-Speed HDLC Mode.
Clear-Channel Framer Mode - TxOHInd:
In the Clear-Channel Framer Mode, this output pin functions as the transmit over-
head data indicator for the local terminal equipment. This output pin is pulsed
"High" for one DS3 or E3 bit period in order to indicate to the local terminal
equipment that the Transmit Section of the Framer is going to be processing an
overhead bit, upon the next rising edge of TxInClk., and will NOT latch the data
that is applied to the TxSer input pin. Therefore, when the local terminal equip-
ment samples the TxOHInd output pin "High", then it must not apply the next
payload bit to TxSer input pin. This output pin serves as a warning that this par-
ticular payload bit is going to be ignored by the Transmit Section of the Framer,
and will not be inserted into payload bits, within the outbound DS3 or E3 data
stream.
ATM/PLCP Mode - TxPFrame:
If the XRT79L71 is configured to operate in the ATM UNI/PLCP Mode, then this
output pin will denote the boundaries of outbound PLCP frames, as they are
being processed by the Transmit PLCP Processor block. This output pulses
"High" when the last nibble of a given PLCP frame is being routed to the Transmit
DS3/E3 Framer block.
This output pin is inactive if the XRT79L71 is operating in the Direct-Mapped
ATM Mode.
High-Speed HDLC Controller Mode - TxHDLCDat_6:
If the XRT79L71 is configured to operate in the High-Speed HDLC Controller
mode, then the local terminal equipment will be provided with a byte-wide Trans-
mit HDLC Controller byte-wide input interface. This input pin will function as Bit 6
within this byte wide interface.
Data, residing on the Transmit HDLC Controller byte wide input interface, will be
sampled upon the rising edge of the TxHDLCClk output signal.
P
IN
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N
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TYPE
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ESCRIPTION