
XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. P1.1.3
á
PRELIMINARY
X
R
X
DS3 I
NTERRUPT
E
NABLE
R
EGISTER
(A
DDRESS
= 0
X
12) ..................................................................... 237
R
X
DS3 I
NTERRUPT
S
TATUS
R
EGISTER
(A
DDRESS
= 0
X
13) ..................................................................... 237
R
X
DS3 FEAC I
NTERRUPT
E
NABLE
/S
TATUS
R
EGISTER
(A
DDRESS
= 0
X
17) ............................................. 238
R
X
DS3 FEAC I
NTERRUPT
E
NABLE
/S
TATUS
R
EGISTER
(A
DDRESS
= 0
X
17) ............................................. 238
R
X
DS3 FEAC I
NTERRUPT
E
NABLE
/S
TATUS
R
EGISTER
(A
DDRESS
= 0
X
17) ............................................. 239
R
X
DS3 FEAC I
NTERRUPT
E
NABLE
/S
TATUS
R
EGISTER
(A
DDRESS
= 0
X
17) ............................................. 239
R
X
DS3 LAPD C
ONTROL
R
EGISTER
(A
DDRESS
= 0
X
18) ......................................................................... 240
R
X
DS3 LAPD C
ONTROL
R
EGISTER
(A
DDRESS
= 0
X
18) ......................................................................... 240
5.0 E3/ITU-T G.751 Operation of the XRT72L50 ..................................................................................... 241
F
RAMER
O
PERATING
M
ODE
R
EGISTER
(A
DDRESS
= 0
X
00) ..................................................................... 241
5.1 D
ESCRIPTION
OF
THE
E3, ITU-T G.751 F
RAMES
AND
A
SSOCIATED
O
VERHEAD
B
ITS
........................................... 241
Figure 97. Illustration of the E3, ITU-T G.751 Framing Format. ......................................................... 241
5.1.1 Definition of the Overhead Bits .............................................................................................................. 241
5.2 T
HE
T
RANSMIT
S
ECTION
OF
THE
XRT72L50 (E3, ITU-T G.751 M
ODE
O
PERATION
) ............................................ 242
Figure 98. A Simple Illustration of the XRT72L50 Transmit Section when it has been configured to operate
in the E3 Mode .................................................................................................................................... 242
5.2.1 The Transmit Payload Data Input Interface Block ................................................................................. 242
Figure 99. A Simple Illustration of the Transmit Payload Data Input Interface Block ......................... 243
T
ABLE
46: L
ISTING
AND
D
ESCRIPTION
OF
THE
PINS
ASSOCIATED
WITH
THE
T
RANSMIT
P
AYLOAD
D
ATA
I
NPUT
I
N
-
TERFACE
............................................................................................................................................... 244
Figure 100. Illustration of the Terminal Equipment being interfaced to the Transmit Payload Data Input In-
terface block of the XRT72L50 for Mode 1 (Serial/Loop-Timed) Operation ........................................ 245
T
X
E3 C
ONFIGURATION
R
EGISTER
(A
DDRESS
= 0
X
30) ............................................................................ 246
Figure 101. Behavior of the Terminal Interface signals between the XRT72L50 Transmit Payload Data Input
Interface block and the Terminal Equipment (for Mode 1 Operation) .................................................. 248
F
RAMER
O
PERATING
M
ODE
R
EGISTER
(A
DDRESS
= 0
X
00) ..................................................................... 248
Figure 102. Illustration of the Terminal Equipment being interfaced to the Transmit Payload Data Input In-
terface block of the XRT72L50 for Mode 2 (Serial/Local-Timed/Frame-Slave) Operation .................. 249
Figure 103. Behavior of the Terminal Interface signals between the XRT72L50 and the Terminal Equipment
(Mode 2 Operation) ............................................................................................................................. 250
F
RAMER
O
PERATING
M
ODE
R
EGISTER
(A
DDRESS
= 0
X
00) ..................................................................... 250
Figure 104. Illustration of the Terminal Equipment being interfaced to the Transmit Payload Data Input In-
terface block of the XRT72L50 for Mode 3 (Serial/Local-Time/Frame-Master) Operation .................. 251
Figure 105. Behavior of the Terminal Interface signals between the XRT72L50 and the Terminal Equipment
(E3 Mode 3 Operation) ........................................................................................................................ 252
F
RAMER
O
PERATING
M
ODE
R
EGISTER
(A
DDRESS
= 0
X
00) ..................................................................... 252
Figure 106. Illustration of the Terminal Equipment being interfaced to the Transmit Payload Data Input In-
terface block of the XRT72L50 for Mode 4 (Nibble-Parallel/Loop-Timed) Operation .......................... 253
Figure 107. Behavior of the Terminal Interface signals between the XRT72L50 and the Terminal Equipment
(Mode 4 Operation) ............................................................................................................................. 254
F
RAMER
O
PERATING
M
ODE
R
EGISTER
(A
DDRESS
= 0
X
00) ..................................................................... 254
Figure 108. Illustration of the Terminal Equipment being interfaced to the Transmit Payload Data Input In-
terface block of the XRT72L50 for Mode 5 (Nibble-Parallel/Local-Timed/Frame-Slave) Operation .... 256
Figure 109. Behavior of the Terminal Interface signals between the XRT72L50 and the Terminal Equipment
(E3, Mode 5 Operation) ....................................................................................................................... 257
F
RAMER
O
PERATING
M
ODE
R
EGISTER
(A
DDRESS
= 0
X
00) ..................................................................... 257
Figure 110. Illustration of the Terminal Equipment being interfaced to the Transmit Payload Data Input In-
terface block of the XRT72L50 for Mode 6 (Nibble-Parallel/Local-Timed/Frame-Master) Operation .. 258
Figure 111. Behavior of the Terminal Interface signals between the XRT72L50 and the Terminal Equipment
(E3 Mode 6 Operation) ........................................................................................................................ 259
F
RAMER
O
PERATING
M
ODE
R
EGISTER
(A
DDRESS
= 0
X
00) ..................................................................... 259
5.2.2 The Transmit Overhead Data Input Interface ........................................................................................ 259
Figure 112. Simple Illustration of the Transmit Overhead Data Input Interface block ........................ 260
T
ABLE
47: A L
ISTING
OF
THE
O
VERHEAD
BITS
WITHIN
THE
E3
FRAME
,
AND
THEIR
POTENTIAL
SOURCES
,
WITHIN
THE
XRT72L50 IC ................................................................................................................................ 261