XRT74L73 Datasheet, PDF (336/488 Pages) Exar Corporation – 3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER

XRT74L73
3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
REV. P1.0.1
PRELIMINARY
I/O CONTROL REGISTER (ADDRESS = 0X01)
BIT 7
Disable TxLOC
BIT 6
LOC
BIT 5
Disable
RxLOC
BIT 4
AMI/ZeroSup*
BIT 3
Unipolar/
Bipolar*
BIT2
BIT 1
TxLine CLK RxLine CLK
Invert
Invert
BIT 0
Reframe
R/W
RO
R/W
R/W
R/W
R/W
R/W
R/W
1
0
1
0
0
0
0
0
Table 75 relates the value of this bit-field to the Re-
ceive E3 LIU Interface Input Mode.
TABLE 75: THE RELATIONSHIP BETWEEN THE CONTENTS OF BIT 2 (TXLINECLK INV) WITHIN THE I/O CONTROL
REGISTER AND THE TXLINECLK CLOCK EDGE THAT TXPOS AND TXNEG ARE UPDATED ON
BIT 3
0
1
RECEIVE E3 LIU INTERFACE INPUT MODE
Bipolar Mode (Dual Rail): AMI or HDB3 Line Codes are Transmitted and Received.
Unipolar Mode (Single Rail) Mode of transmission and reception of E3 data is selected.
NOTES:
1. The default condition is the Bipolar Mode.
2. This selection also effects the Transmit E3 Framer
Line Interface Output Mode
5.3.1.2 Bipolar Decoding
If the Receive E3 LIU Interface block is operating in
the Bipolar Mode, then it will receive the E3 data puls-
es via both the RxPOS, RxNEG, and the RxLineClk
input pins. Figure 137 presents a circuit diagram il-
lustrating how the Receive E3 LIU Interface block in-
terfaces to the Line Interface Unit while the Framer is
operating in Bipolar mode. The Receive E3 LIU Inter-
face block can be configured to decode either the
AMI or HDB3 line codes.
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