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PRELIMINARY
XRT79L71
270
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
Operation of the Transmit Payload Data Input Interface Block
The Transmit Payload Data Input Interface block permits the user to configure it to operate in the following
combination of modes.
The Serial or Nibble-Parallel Interface Mode
The Loop-Timing or Local-Timing Mode
If the XRT79L71 is configured to operate in the Local-Timing Mode, then there are two additional sub-options.
The Frame-Master or Frame-Slave Mode
With these three sets of configuration options, the Transmit Payload Data Input Interface block can be
configured to operate in any one of the following six (6) Modes.
Mode 1 - Serial/Loop-Timing Mode
Mode 2 - Serial/Local-Timing/Frame Slave Mode
Mode 3 - Serial/Local-Timing/Frame Master Mode
Mode 4 - Nibble-Parallel/Loop-Timing Mode
Mode 5 - Nibble-Parallel/Local-Timing/Frame Slave Mode
Mode 6 - Nibble-Parallel/Local-Timing/Frame Master Mode
TxFrameRef
A11
I
Transmit E3 Frame Reference Input:
The XRT79L71 permits the user to configure this input pin to function as the Transmit
E3 Frame Generation Reference Input. If this particular configuration option is
invoked, the TransmitE3 Framer block within the XRT79L71 will initiate E3 frame gen-
eration anytime it detects a rising edge of this input pin.
NOTE: To implement this configuration option, it is imperative that this particular input
signal is synchronous with the TxInClk input signal. Failure to do so will result
in the transmission of erred E3 frames to the remote terminal equipment.
RxOutClk
B5
O
Loop-Timing Reference Clock Output Pin:
If the XRT79L71 is configured to operate in the Loop-Timing Mode, then the Transmit
Section of the XRT79L71 will be configured to use the LIU Recovered Clock signal as
its timing source. In this case, the XRT79L71 will output a 34.368MHz clock signal via
this particular output pin. In this configuration, the TxInClk signal will be inactive and
will NOT be used to sample and latch the data on the TxSer input pin. In this case, the
XRT79L71 will now be configured to sample the TxSer input pin upon the rising edge
of the RxOutClk signal.
NOTE: This output pin will always be active, in the sense that it will always generate a
34.368MHz clock signal even when the XRT79L71 is NOT configured to
operate in the Loop-Timing Mode. However, the XRT79L71 will only use this
particular clock signal to sample and latch the data on the TxSer input pin
whenever the XRT79L71 has been configured to operate in the Loop-Timing
Mode.
TABLE 36: LIST AND DESCRIPTION OF THE PINS ASSOCIATED WITH THE TRANSMIT PAYLOAD DATA INPUT INTERFACE
BLOCK
SIGNAL NAME
PIN/
BALL #
TYPE
DESCRIPTION