
á
XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. 1.2.1
VII
T
ABLE
40: L
ISTING
AND
D
ESCRIPTION
OF
THE
P
IN
A
SSOCIATED
WITH
THE
R
ECEIVE
O
VERHEAD
D
ATA
O
UTPUT
I
NTERFACE
B
LOCK
(M
ETHOD
2) .................................................................................................................................................. 216
Figure 78. The Terminal Equipment being interfaced to the Receive Overhead Data Output Interface (Method 2) ... 217
T
ABLE
41: T
HE
R
ELATIONSHIP
BETWEEN
THE
N
UMBER
OF
R
X
OHE
NABLE
OUTPUT
PULSES
((
SINCE
R
X
OHF
RAME
WAS
LAST
SAMPLED
"H
IGH
")
TO
THE
DS3 O
VERHEAD
B
IT
,
THAT
IS
BEING
OUTPUT
VIA
THE
R
X
OH
OUTPUT
PIN
................. 218
4.3.5 The Receive Payload Data Output Interface ......................................................................................... 220
Figure 79. Illustration of the signals that are output via the Receive Overhead Data Output Interface block (for Method 2).
220
Figure 80. The Receive Payload Data Output Interface block .................................................................................... 220
T
ABLE
42: L
ISTING
AND
D
ESCRIPTION
OF
THE
PIN
ASSOCIATED
WITH
THE
R
ECEIVE
P
AYLOAD
D
ATA
O
UTPUT
I
NTERFACE
BLOCK
221
4.3.5.1 Serial Mode Operation ................................................................................................................ 222
Figure 81. The XRT72L50 DS3/E3 Framer IC being interfaced to the Receive Terminal Equipment (Serial Mode Operation)
222
4.3.5.2 Nibble-Parallel Mode Operation .................................................................................................. 223
Figure 82. An Illustration of the behavior of the signals between the Receive Payload Data Output Interface block of the
XRT72L50 and the Terminal Equipment (Serial Mode Operation) .............................................................. 223
Figure 83. The XRT72L50 DS3/E3 Framer IC being interfaced to the Receive Section of the Terminal Equipment (Nibble-
Parallel Mode Operation) ............................................................................................................................. 224
4.3.6 Receive Section Interrupt Processing ................................................................................................... 225
4.3.6.1 Enabling Receive Section Interrupts ........................................................................................... 225
Figure 84. An Illustration of the Behavior of the signals between the Receive Payload Data Output Interface Block of the
XRT72L50 and the Terminal Equipment (Nibble-Mode Operation). ............................................................ 225
4.3.6.2 Enabling/Disabling and Servicing Receive Section Interrupts .................................................... 226
5.0 E3/ITU-T G.751 Operation of the XRT72L50 .................................................................................... 239
5.1 D
ESCRIPTION
OF
THE
E3, ITU-T G.751 F
RAMES
AND
A
SSOCIATED
O
VERHEAD
B
ITS
........................................... 239
5.1.1 Definition of the Overhead Bits ............................................................................................................. 239
5.1.1.1 The A (Alarm) Bit ........................................................................................................................ 239
Figure 85. Illustration of the E3, ITU-T G.751 Framing Format. .................................................................................. 239
5.1.1.2 The N Bit ..................................................................................................................................... 240
5.2 T
HE
T
RANSMIT
S
ECTION
OF
THE
XRT72L50 (E3, ITU-T G.751 M
ODE
O
PERATION
) ........................................... 240
5.2.1 The Transmit Payload Data Input Interface Block ................................................................................. 241
Figure 86. The XRT72L50 Transmit Section configured to operate in the E3 Mode ................................................... 241
Figure 87. The Transmit Payload Data Input Interface Block ...................................................................................... 241
T
ABLE
43: L
ISTING
AND
D
ESCRIPTION
OF
THE
PINS
ASSOCIATED
WITH
THE
T
RANSMIT
P
AYLOAD
D
ATA
I
NPUT
I
NTERFACE
... 242
5.2.1.1 Mode 1 - The Serial/Loop-Timing Mode The Behavior of the XRT72L50 ................................... 243
Figure 88. The Terminal Equipment being interfaced to the Transmit Payload Data Input Interface block for Mode 1 (Serial/
Loop-Timed) Operation ............................................................................................................................... 244
Figure 89. Behavior of the Terminal Interface signals between the XRT72L50 Transmit Payload Data Input Interface block
and the Terminal Equipment (for Mode 1 Operation) ................................................................................... 246
5.2.1.2 Mode 2 - The Serial/Local-Timed/Frame-Slave Mode Behavior of the XRT72L50 ..................... 247
Figure 90. The Terminal Equipment being interfaced to the Transmit Payload Data Input Interface block for Mode 2 (Serial/
Local-Timed/Frame-Slave) Operation .......................................................................................................... 247
Figure 91. Behavior of the Terminal Interface signals between the XRT72L50 and the Terminal Equipment (Mode 2
Operation) .................................................................................................................................................... 248
5.2.1.3 Mode 3 - The Serial/Local-Timed/Frame-Master Mode Behavior of the XRT72L50 ................... 249
Figure 92. The Terminal Equipment being interfaced to the Transmit Payload Data Input Interface block for Mode 3 (Serial/
Local-Timed/Frame-Master) Operation ........................................................................................................ 250
5.2.1.4 Mode 4 - The Nibble-Parallel/Loop-Timed Mode Behavior of the XRT72L50 ............................. 251
Figure 93. Behavior of the Terminal Interface signals between the XRT72L50 and the Terminal Equipment (E3 Mode 3
Operation) .................................................................................................................................................... 251
Figure 94. The Terminal Equipment being interfaced to the Transmit Payload Data Input Interface block for Mode 4 (Nibble-
Parallel/Loop-Timed) Operation ................................................................................................................... 252
Figure 95. Behavior of the Terminal Interface signals between the XRT72L50 and the Terminal Equipment (Mode 4
Operation) .................................................................................................................................................... 253
5.2.1.5 Mode 5 - The Nibble-Parallel/Local-Timed/Frame-Slave Interface Mode Behavior of the XRT72L50
254
Figure 96. The Terminal Equipment being interfaced to the Transmit Payload Data Input Interface block for Mode 5 (Nibble-
Parallel/Local-Timed/Frame-Slave) Operation ............................................................................................. 255
5.2.1.6 4.2.1.6 Mode 6 - The Nibble-Parallel/Local-Timed/Frame-Master Interface Mode Behavior of the
XRT72L50 ............................................................................................................................................... 256
Figure 97. Behavior of the Terminal Interface signals between the XRT72L50 and the Terminal Equipment (E3, Mode 5
Operation) .................................................................................................................................................... 256