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XRT79L71
PRELIMINARY
437
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
6.2.1.1
Mode 1 - Serial/Loop-Timing Mode Operation of the Transmit Payload Data Input Interface
Block
If the XRT79L71 is configured to operate in "Mode 1" then all of the following is true.
The XRT79L71 will be configured to operate in the Loop-Timing Mode. In other words, the Transmit Section
of the XRT79L71 will use the Recovered Clock signal (from the Receive E3 LIU Block) as its timing source.
Since the XRT79L71 is configured to operate in the "Serial-Mode", it will sample and latch the data, being
applied to the "TxSer" input pin upon the rising edge of the "RxOutClk" output signal.
The XRT79L71 will pulse the "TxFrame" output pin "high" for one bit period coincident to whenever the
Transmit Payload Data Input Interface block is processing the very last bit within a given E3 frame.
TABLE 57: A SUMMARY OF THE "TRANSMIT PAYLOAD DATA INPUT INTERFACE" MODES
MODE
NIBBLE-
PARALLEL/
SERIAL MODE
SOURCE OF "SYSTEM-SIDE TERMINAL EQUIPMENT" CLOCK
FRAMING ALIGNMENT
TIMING SOURCE
1
Serial
Loop-Timing Mode:
The XRT79L71 will output a 34.368MHz clock signal via the
"RxOutClk" output pin. This clock signal is ultimately derived from
Recovered Line Clock (from Receive DS3/E3 LIU Block).
Asynchronous upon
Power up.
2
Serial
Local-Timing Mode:
The user is expected to apply a 34.368MHz clock signal to the TxIn-
Clk Input pin
TxFrameRef Input
3
Serial
Local-Timing Mode:
The user is expected to apply a 34.368MHz clock signal to the TxIn-
Clk Input pin
Asynchronous upon
Power up
4
Nibble-Parallel Loop-Timing Mode:
The XRT79L71 will output an 8.592MHz "Nibble-Clock" signal (via
the "TxNibClk" output). This clock signal is ultimately derived from
the Recovered Line Clock (from the Receive DS3/E3 LIU Block).
Asynchronous upon
Power up
5
Nibble-Parallel Local-Timing Mode:
The user is expected to apply a 34.368MHz clock to the TxInClk
input pin. The XRT79L71 will use the TxInClk signal to derive the
8.592MHz clock signal (which is output via the "TxNibClk" output
pin).
TxFrameRef Input pin
6
Nibble-Parallel Local-Timing Mode:
The user is expected to apply a 34.368MHz clock signal to the TxIn-
Clk input pin. The XRT79L7 will use the TxInClk signal to derive
the 8.592MHz clock signal (which is output via the "TxNibClk" out-
put pin).
Asynchronous upon
Power up