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XRT79L71
PRELIMINARY
453
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
The user can configure the XRT79L71 to operate in Mode 6 by executing the following steps.
STEP 1 - Design your board such that the System-Side Terminal Equipment circuitry interfaces to the
Transmit Payload Data Input Interface in the manner as depicted above in Figure 216. STEP 2 - Configure the XRT79L71 to operate in the "Nibble-Parallel" Mode
This can be accomplished by setting the "NibIntf" input pin to a logic "HIGH".
STEP 3 - Configure the XRT79L71 to operate in the Local-Timing/Frame Master Mode
This can be accomplished by setting Bits 1 and 0 (TimRefSel[1:0]) within the "Framer Operating Mode"
Register to "[1, X]" as depicted below.
6.2.1.7
Operating the Transmit Payload Data Input Interface in the Gapped Clock Mode
In contrast to the DS3 Mode, if the XRT79L71 has been configured to operate in the "E3, ITU-T G.832" Mode,
then the Transmit Payload Data Input Interface block can be configured to operate in either the "Gapped-
Clock" or the "Non-Gapped Clock" Mode as described below.
6.2.1.7.1
Operating the Transmit Payload Data Input Interface in the "Serial/Gapped-Clock" Mode
This particular section discusses both the "Non-Gapped Clock" and the "Gapped-Clock" Modes of operation of
the Transmit Payload Data Input Interface block.
If the Transmit Payload Data Input Interface block has been configured to operate in the "Non-Gapped
Clock" Mode
If the Transmit Payload Data Input Interface (within the XRT79L71) has been configured to operate in any one
BLOCK” ON PAGE 442.), then we have recommended that the user design or configure their "System-Side"
Terminal Equipment to perform the following procedure, when supplying payload data to the "TxSer" input pin.
Check the state of the "TxOH_Ind" output pin (from the XRT79L71) upon the falling edge of either the
"TxInClk" or the "RxOutClk" signal.
Perform either of the following actions, depending upon the sampled state of the "TxOH_Ind" output pin, as
described below.
If TxOH_Ind is sampled "LOW"
Then the "System-Side Terminal Equipment" should proceed to place the very next "payload" bit on the
"TxSer" input pin upon the very next rising edge of either the "TxInClk" or "RxOutClk" signal.
If TxOH_Ind is sampled "HIGH"
Then the "System-Side Terminal Equipment should NOT proceed to place the very next "payload" bit on the
"TxSer" input pin, upon the very next rising edge of either the "TxInClk" or "RxOutClk" signal. In this case, the
Framer Operating Mode Register (Address = 0x1100)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Local
Loop Back
IsDS3
Internal
LOS
Enable
RESET
Direct
Mapped
ATM
Frame
Format
TimRefSel[1:0]
R/W
0
1
0
1
X