XRT74L73
3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
PRELIMINARY
REV. P1.0.1
32
AD7
AE7
AF7
TxNib_0_0/
TxGFC_0/
TxHDLCDat_0_0
TxNib_0_1/
TxGFC_1/
TxHDLCDat_0_1
TxNib_0_2/
TxGFC_2/
TxHDLCDat_0_2
I
Transmit Nibble Interface - Bit 0/Transmit GFC Input pin/Transmit HDLC
Controller Data Bus - Bit 0 Input:
The exact function of this input pin depends upon whether the XRT74L73 device
is configured to operate in the Clear-Channel Framer Mode, the High Speed
HDLC Controller Mode or in the ATM Mode.
Clear-Channel Framer Mode - TxNib_0_n:
If the user opts to operate the XRT74L73 device in the Nibble-Parallel Mode,
then this input pin will function as the bit 0 (LSB) input to the "Transmit Nibble-
Parallel" input interface. The Transmit Payload Data Input Interface block will
sample this signal (along with TxNib_1_n through TxNib_3_n) upon the falling
edge of TxNibClk_n.
N
OTE
:
This input pin is inactive if the Channel is configured to operate in the
"Serial" Mode.
ATM Mode - TxGFC_n:
This signal, along with TxGFCMSB_n and TxGFCClk_n combine to function as
the "Transmit GFC Nibble Field" serial input port. The user will specify the value
of the GFC field, within a given ATM cell, by serially transmitting its four bit-value
into this input pin. Each of these four bits will be clocked into the port upon the
rising edge of the TxGFCClk_n output signal.
High-Speed HDLC Controller Mode - TxHDLCDat_0_n:
If the channel is configured to operate in the High-Speed HDLC Controller mode,
then the local terminal equipment will be provided with a "byte-wide" Transmit
HDLC Controller byte-wide input interface. This input pin will function as "Bit 0"
(the LSB) 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_n output signal.
AF5
AE6
AF6
TxGFCClk_0
TxGFCClk_1
TxGFCClk_2
O
Transmit GFC Nibble-Field Serial Input port - Clock Output signal:
This signal along with TxGFC_n and TxGFCMSB_n combine to function as the
"Transmit GFC Nibble-field" serial input port. This output signal functions as the
demand clock signal for this port. The user will specify the value of the GFC
field, within a given ATM cell, by serially transmitting its four bit-value into the
"TxGFC_n" input pin. The Transmit GFC Nibble-Field" serial input port will latch
the contents of "TxGFC_n" upon the rising edge of this clock signal. Hence, the
local terminal equipment should be designed to place its "outbound" GFC bits on
to the "TxGFC_n" line, upon the falling edge of this clock signal.
N
OTE
:
This output pin is only active if the XRT74L73 device has been configure
to operate in the ATM Mode.
PIN DESCRIPTION
P
IN
#
N
AME
T
YPE
D
ESCRIPTION