XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. 1.2.1
á
VIII
Figure 98. The Terminal Equipment being interfaced to the Transmit Payload Data Input Interface block for Mode 6 (Nibble-
Parallel/Local-Timed/Frame-Master) Operation ........................................................................................... 257
Figure 99. Behavior of the Terminal Interface signals between the XRT72L50 and the Terminal Equipment (E3 Mode 6
Operation) .................................................................................................................................................... 258
5.2.2 The Transmit Overhead Data Input Interface ........................................................................................ 259
Figure 100. The Transmit Overhead Data Input Interface block .................................................................................. 259
5.2.2.1 Method 1 - Using the TxOHClk Clock Signal .............................................................................. 260
T
ABLE
44: A L
ISTING
OF
THE
O
VERHEAD
BITS
WITHIN
THE
E3
FRAME
,
AND
THEIR
POTENTIAL
SOURCES
,
WITHIN
THE
XRT72L50 IC
260
T
ABLE
45: D
ESCRIPTION
OF
M
ETHOD
1 T
RANSMIT
O
VERHEAD
I
NPUT
I
NTERFACE
S
IGNALS
............................................... 261
Figure 101. The Terminal Equipment being interfaced to the Transmit Overhead Data Input Interface (Method 1) ... 262
T
ABLE
46: T
HE
R
ELATIONSHIP
BETWEEN
THE
N
UMBER
OF
R
ISING
C
LOCK
E
DGES
IN
T
X
OHC
LK
, (
SINCE
T
X
OHF
RAME
WAS
LAST
SAMPLED
"H
IGH
")
TO
THE
E3 O
VERHEAD
B
IT
,
THAT
IS
BEING
PROCESSED
........................................................ 263
Figure 102. Illustration of the signal that must occur between the Terminal Equipment and the XRT72L50 in order to
configure the XRT72L50 to transmit a Yellow Alarm to the remote terminal equipment .............................. 264
5.2.2.2 Method 2 - Using the TxInClk and TxOHEnable Signals ............................................................ 265
T
ABLE
47: D
ESCRIPTION
OF
M
ETHOD
2 T
RANSMIT
O
VERHEAD
I
NPUT
I
NTERFACE
S
IGNALS
............................................... 265
Figure 103. The Terminal Equipment being interfaced to the Transmit Overhead Data Input Interface (Method 2) ... 266
T
ABLE
48: T
HE
R
ELATIONSHIP
BETWEEN
THE
N
UMBER
OF
T
X
OHE
NABLE
PULSES
(
SINCE
THE
LAST
OCCURRENCE
OF
THE
T
X
OHF
RAME
PULSE
)
TO
THE
E3 O
VERHEAD
B
IT
,
THAT
IS
BEING
PROCESSED
BY
THE
XRT72L50 ..................... 267
5.2.3 The Transmit E3 HDLC Controller ......................................................................................................... 268
5.2.3.1 Message-Oriented Signaling (e.g., LAP-D) processing via the Transmit E3 HDLC Controller ... 268
Figure 104. Behavior of Transmit Overhead Data Input Interface signals between the XRT72L50 and the Terminal Equipment
(for Method 2) .............................................................................................................................................. 268
Figure 105. LAPD Message Frame Format ................................................................................................................ 269
T
ABLE
49: T
HE
LAPD M
ESSAGE
T
YPE
AND
THE
C
ORRESPONDING
VALUE
OF
THE
F
IRST
B
YTE
,
WITHIN
THE
I
NFORMATION
P
AYLOAD
270
T
ABLE
50: R
ELATIONSHIP
BETWEEN
T
X
LAPD M
SG
L
ENGTH
AND
THE
LAPD M
ESSAGE
S
IZE
............................................ 271
Figure 106. Flow Chart Depicting how to use the LAPD Transmitter .......................................................................... 274
5.2.4 The Transmit E3 Framer Block .............................................................................................................. 275
5.2.4.1 Brief Description of the Transmit E3 Framer ............................................................................... 275
5.2.4.2 Detailed Functional Description of the Transmit E3 Framer Block .............................................. 276
Figure 107. The Transmit E3 Framer Block and the associated paths to other Functional Blocks ............................. 277
T
ABLE
51: T
HE
R
ELATIONSHIP
BETWEEN
THE
CONTENTS
OF
B
IT
2 (T
X
AIS E
NABLE
)
WITHIN
THE
T
X
E3 C
ONFIGURATION
R
EGISTER
,
AND
THE
RESULTING
T
RANSMIT
E3 F
RAMER
B
LOCK
'
S
A
CTION
.......................................................................... 278
T
ABLE
52: T
HE
R
ELATIONSHIP
BETWEEN
THE
CONTENTS
OF
B
IT
1 (T
X
LOS)
WITHIN
THE
T
X
E3 C
ONFIGURATION
R
EGISTER
,
AND
THE
RESULTING
T
RANSMIT
E3 F
RAMER
B
LOCK
'
S
A
CTION
........................................................................................ 278
5.2.5 The Transmit E3 Line Interface Block ................................................................................................... 281
Figure 108. Interfacing the XRT72L50 Framer IC to the XRT73L00 DS3/E3/STS-1 LIU ............................................ 282
Figure 109. The Transmit E3 LIU Interface block ........................................................................................................ 282
5.2.5.1 Selecting the various Line Codes ................................................................................................ 283
Figure 110. The Behavior of TxPOS and TxNEG signals during data transmission while the Transmit E3 LIU Interface is
operating in the Unipolar Mode .................................................................................................................... 283
T
ABLE
53: T
HE
R
ELATIONSHIP
BETWEEN
THE
CONTENT
OF
B
IT
3 (U
NIPOLAR
/B
IPOLAR
)
WITHIN
THE
UNI I/O C
ONTROL
R
EGISTER
AND
THE
T
RANSMIT
E3 F
RAMER
L
INE
I
NTERFACE
O
UTPUT
M
ODE
..................................................................... 284
Figure 111. Illustration of AMI Line Code .................................................................................................................... 284
5.2.5.2 TxLineClk Clock Edge Selection ................................................................................................. 285
Figure 112. Illustration of two examples of HDB3 Encoding ....................................................................................... 285
T
ABLE
54: T
HE
R
ELATIONSHIP
BETWEEN
B
IT
4 (AMI/HDB3*)
WITHIN
THE
I/O C
ONTROL
R
EGISTER
AND
THE
B
IPOLAR
L
INE
C
ODE
THAT
IS
OUTPUT
BY
THE
T
RANSMIT
E3 LIU I
NTERFACE
B
LOCK
......................................................................... 285
T
ABLE
55: T
HE
R
ELATIONSHIP
BETWEEN
THE
CONTENTS
OF
B
IT
2 (T
X
L
INE
C
LK
I
NV
)
WITHIN
THE
I/O C
ONTROL
R
EGISTER
AND
THE
T
X
L
INE
C
LK
CLOCK
EDGE
THAT
T
X
POS
AND
T
X
NEG
ARE
UPDATED
ON
............................................................ 286
Figure 113. Waveform/Timing Relationship between TxLineClk, TxPOS and TxNEG - TxPOS and TxNEG are configured to
be updated on the rising edge of TxLineClk ................................................................................................ 286
5.2.6 Transmit Section Interrupt Processing .................................................................................................. 287
5.2.6.1 Enabling Transmit Section Interrupts .......................................................................................... 287
Figure 114. Waveform/Timing Relationship between TxLineClk, TxPOS and TxNEG - TxPOS and TxNEG are configured to
be updated on the falling edge of TxLineClk ............................................................................................... 287
5.3 T
HE
R
ECEIVE
S
ECTION
OF
THE
XRT72L50 (E3 M
ODE
O
PERATION
) .................................................................... 289
Figure 115. The XRT72L50 Receive Section configured to operate in the E3 Mode ................................................. 289
5.3.1 The Receive E3 LIU Interface Block ...................................................................................................... 290
5.3.1.1 Unipolar Decoding ....................................................................................................................... 290
Figure 116. The Receive E3 LIU Interface Block ........................................................................................................ 290
5.3.1.2 Bipolar Decoding ......................................................................................................................... 291