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PRELIMINARY
XRT79L71
588
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
SOME THINGS TO NOTE ABOUT THE FRAMER LOCAL LOOP-BACK MODE:
1.
Whenever the XRT79L71 is configured to operate in the "Framer Local Loop-back" Mode, the output of
the Transmit DS3/E3 Framer block signal MAY still be output to the remote terminal equipment
(depending upon the state of the "TxON" bit-field - see Note 3, below). A replica of this "Transmit Output"
signal will also be routed into the input of the Receive DS3/E3 Framer block.
2.
Whenever the XRT79L71 is configured to operate in the "Framer Local Loop-back" Mode, then the
Receive DS3/E3 Framer block will ignore any data that it receives from the Receive DS3/E3 LIU Block.
3.
In contrast to the "LIU Analog Local Loop-back" Mode, the "Framer Local Loop-back" Mode will NOT be
broken (e.g., this loop-back mode will still function) even if the user sets Bit 0 (TxON), within the "LIU
Transmit APS/Redudancy Control" Register to "0" as depicted below.
Configuring the XRT79L71 to operate in the "Framer Local Loop-back" Mode
To configure the XRT79L71 to operate in the "Framer Local Loop-back" Mode execute the following steps.
FIGURE 270. ILLUSTRATION OF THE FUNCTIONAL BLOCK DIAGRAM OF THE XRT79L71 (WHEN CONFIGURED TO
OPERATE IN THE
"CLEAR-CHANNEL FRAMER" MODE) WITH THE "FRAMER LOCAL LOOP-BACK" PATH INDICATED
LIU Transmit APS/Redundancy Control Register (Address = 0x1300)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
TxON
R/O
R/W
0
Transmit Payload
Data Input
Interface Block
Transmit DS3/E3
Framer Block
DS3/E3
Jitter
Attenuator
Block
DS3/E3
Jitter
Attenuator
Block
DS3/E3
Jitter
Attenuator
Block
DS3/E3
Jitter
Attenuator
Block
Receive DS3/E3
Framer Block
Receive Payload
Data Output
Interface Block
Microprocessor
Interface
TxSer
TxNib[3:0]
TxInClk
MOTO
D[7:0]
A[8:0]
IntB*
CSB*
RdB_DS
WrB_RW
Rdy_Dtck
Reset*
ALE_AS
RxSer
RxNib[3:0]
RxOutClk
Tx LAPD Buffer/
Controller
Rx LAPD Buffer/
Controller
Transmit Overhead
Input
Interface Block
Receive Overhead
Output
Interface Block
TxOHClk
TxOHIns
TxOHInd
TxOH
TxOHEnable
TxOHFrame
TxNibClk
TxFrame
RxNibClk
RxFrame
RxOHFrame
RxOH
RxOHClk
RxOHEnable
RxOHInd
Transmit
DS3/E3
LIU Block
Transmit
DS3/E3
LIU Block
Receive
DS3/E3
LIU Block
Receive
DS3/E3
LIU Block
TTIP
TRING
RTIP
RRING
Only one JA exists.
Can be configured in
Tx or Rx Path
Framer Local Loop-back
Mode