PRELIMINARY
XRT79L71
288
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
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 135. 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.
5.2.1.7
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.751 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.
5.2.1.7.1
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
Terminal Equipment to do the following, 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 For-
mat
TimRefSel[1:0]
R/W
0
1
0
1
X