
XRT79L71
PRELIMINARY
331
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
Requirements Associated with the "Loop-Timing" Mode
If the XRT79L71 is configured to operate in the "Loop-Timing" Mode, do the following.
Insure that either one of the following conditions are true.
a. That the Receive DS3/E3 LIU Block is receive a proper E3 line signal from the remote terminal
equipment, or
b. That the SFM Synthesizer block (within the Receive DS3/E3 LIU Block) is configured to generate a
34.368MHz clock (to the remainder of the Receive DS3/E3 LIU Block circuitry) from either an externally
supplied 12.288MHz or a 34.368MHz clock signal. (Please see
Section 5.3.1.5 for details on how to
accomplish this)
Tie the TxFrameRef input pin (Ball A11) to GND.
NOTE: In order to permit the Microprocessor Interface to function (for Revision A silicon) the user is still required to supply
a sufficiently high frequency clock signal to the "TxInClk" input pin, even if the XRT 79L71 is configured to operate
in the "Loop-Timing" Mode.
5.2.4.6
Controlling the State of the N-Bit within the outbound E3 data-stream
5.2.5
TRANSMIT DS3/E3 LIU BLOCK - E3 APPLICATIONS
The Transmit DS3/E3 Framer block is the fifth functional block (within the Transmit Direction) of the XRT79L71
that we will discuss for E3, ITU-T G.751 Clear-Channel Framer Applications.
illustration of the "Transmit Direction" circuitry whenever the XRT79L71 has been configured to operate in the
E3, ITU-T G.751 Clear-Channel Framer Mode, with the "Transmit DS3/E3 LIU" block highlighted.
Framer Operating Mode Register (Address = 0x1100)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Framer
Local
Loop Back
IsDS3
Internal
LOS
Enable
RESET
Direct
Map
ATM
Frame
Format
TimRefSel[1:0]
R/W
0
1
0
1
0