á
XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. 1.2.1
XI
361
6.2.2.1 Method 1 - Using the TxOHClk Clock Signal .............................................................................. 363
T
ABLE
69: D
ESCRIPTION
OF
M
ETHOD
1 T
RANSMIT
O
VERHEAD
I
NPUT
I
NTERFACE
S
IGNALS
............................................... 363
Figure 158. The Terminal Equipment being interfaced to the Transmit Overhead Data Input Interface (Method 1) ... 364
T
ABLE
70: 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
....................................................... 365
Figure 159. 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 .............................. 367
6.2.2.2 Method 2 - Using the TxInClk and
TxOHEnable Signals ............................................................................................................................... 368
T
ABLE
71: D
ESCRIPTION
OF
M
ETHOD
1 T
RANSMIT
O
VERHEAD
I
NPUT
I
NTERFACE
S
IGNALS
............................................... 368
Figure 160. The Terminal Equipment being interfaced to the Transmit Overhead Data Input Interface (Method 2) ... 369
T
ABLE
72: 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 ..................... 369
6.2.3 The Transmit E3 HDLC Controller ........................................................................................................ 372
6.2.3.1 Message-Oriented Signaling (e.g., LAP-D) processing via the Transmit E3 HDLC Controller ... 372
Figure 161. Behavior of Transmit Overhead Data Input Interface signals between the XRT72L50 and the Terminal Equipment
(for Method 2) .............................................................................................................................................. 372
Figure 162. LAPD Message Frame Format ................................................................................................................ 373
T
ABLE
73: T
HE
LAPD M
ESSAGE
T
YPE
AND
THE
C
ORRESPONDING
VALUE
OF
THE
F
IRST
B
YTE
,
WITHIN
THE
I
NFORMATION
P
AYLOAD
374
T
ABLE
74: R
ELATIONSHIP
BETWEEN
T
X
LAPD M
SG
L
ENGTH
AND
THE
LAPD M
ESSAGE
S
IZE
........................................... 375
Figure 163. Flow Chart depicting how to use the LAPD Transmitter (LAPD Transmitter is configured to re-transmit the LAPD
Message frame repeatedly at One-Second intervals) ................................................................................. 379
Figure 164. Flow Chart depicting how to use the LAPD Transmitter (LAPD Transmitter is configured to transmit a LAPD
Message frame only once). ......................................................................................................................... 380
6.2.4 The Transmit E3 Framer Block ............................................................................................................. 381
6.2.4.1 Brief Description of the Transmit E3 Framer ............................................................................... 381
6.2.4.2 Detailed Functional Description of the Transmit E3 Framer Block .............................................. 382
Figure 165. The Transmit E3 Framer Block and the associated paths to other Functional Blocks ............................. 382
T
ABLE
75: 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
.......................................................................... 384
T
ABLE
76: 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
........................................................................................ 384
6.2.5 The Transmit E3 Line Interface Block ................................................................................................... 386
Figure 166. Interfacing the XRT72L50 Framer IC to the XRT73L00 DS3/E3/STS-1 LIU ............................................ 386
Figure 167. The Transmit E3 LIU Interface block ........................................................................................................ 387
Figure 168. The Behavior of TxPOS and TxNEG signals during data transmission while the Transmit E3 LIU Interface is
operating in the Unipolar Mode ................................................................................................................... 387
6.2.5.1 Selecting the various Line Codes ............................................................................................... 388
T
ABLE
77: 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
..................................................................... 388
Figure 169. Illustration of AMI Line Code ................................................................................................................... 389
Figure 170. Illustration of two examples of HDB3 Encoding ....................................................................................... 389
6.2.5.2 TxLineClk Clock Edge Selection ................................................................................................. 390
T
ABLE
78: 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
......................................................................... 390
T
ABLE
79: 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
........................................................... 390
6.2.6 Transmit Section Interrupt Processing .................................................................................................. 391
6.2.6.1 Enabling Transmit Section Interrupts .......................................................................................... 391
Figure 171. Waveform/Timing Relationship between TxLineClk, TxPOS and TxNEG - TxPOS and TxNEG are configured to
be updated on the rising edge of TxLineClk ................................................................................................ 391
Figure 172. Waveform/Timing Relationship between TxLineClk, TxPOS and TxNEG - TxPOS and TxNEG are configured to
be updated on the falling edge of TxLineClk ............................................................................................... 391
6.3 T
HE
R
ECEIVE
S
ECTION
OF
THE
XRT72L50 (E3 M
ODE
O
PERATION
) ................................................................... 393
6.3.1 The Receive E3 LIU Interface Block ..................................................................................................... 394
Figure 173. The XRT72L50 Receive Section configured to operate in the E3 Mode ................................................. 394
6.3.1.1 Unipolar Decoding ...................................................................................................................... 395
Figure 174. The Receive E3 LIU Interface Block ........................................................................................................ 395
Figure 175. Behavior of the RxPOS, RxNEG and RxLineClk signals during data reception of Unipolar Data ........... 395
6.3.1.2 Bipolar Decoding ......................................................................................................................... 396
T
ABLE
80: T
HE
R
ELATIONSHIP
BETWEEN
THE
CONTENTS
OF
B
IT
3 (U
NIPOLAR
/B
IPOLAR
)
WITHIN
THE
I/O C
ONTROL
R
EGISTER
.
396