
á
XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
PRELIMINARY
REV. P1.1.3
V
T
ABLE
10: I
NTERRUPT
S
ERVICE
R
OUTINE
G
UIDE
(
FOR
E3, ITU-T G.832 A
PPLICATIONS
) ....................... 124
T
ABLE
11: I
NTERRUPT
S
ERVICE
R
OUTINE
G
UIDE
(
FOR
E3, ITU-T G.751 A
PPLICATIONS
) ....................... 124
2.6.1 Automatic Reset of Interrupt Enable Bits .............................................................................................. 124
FRAMER
OPERATING
MODE
R
EGISTER
(A
DDRESS
= 0
X
00) ...................................................................... 125
2.6.2 One-Second Interrupts .......................................................................................................................... 125
2.7 I
NTERFACING
THE
FRAMER
TO
AN
INTEL
-
TYPE
MICROPROCESSOR
........................................................................ 125
T
ABLE
12: A
LTERNATE
F
UNCTIONS
OF
P
ORT
3 P
INS
............................................................................. 126
T
ABLE
13: I
NTERRUPT
S
ERVICE
R
OUTINE
L
OCATION
(
IN
C
ODE
M
EMORY
)
FOR
THE
INT0*
AND
INT1* I
NTERRUPT
I
NPUT
PINS
............................................................................................................................................ 127
Figure 37. Schematic depicting how to interface the XRT72L50 DS3/E3 Framer IC to the 8051 Microcon-
troller ................................................................................................................................................... 127
2.8 I
NTERFACING
THE
F
RAMER
IC
TO
A
M
OTOROLA
-
TYPE
M
ICROPROCESSOR
............................................................ 128
Figure 38. Schematic Depicting how to interface the XRT72L50 DS3/E3 Framer IC to the MC68000 Micro-
processor ............................................................................................................................................ 128
T
ABLE
14: A
UTO
-V
ECTOR
T
ABLE
FOR
THE
MC68000 M
ICROPROCESSOR
.............................................. 129
3.0 The Line Interface and scan section ................................................................................................ 129
Figure 39. Schematic Depicting how to interface the XRT72L50 DS3/E3 Framer IC to the XRT73L00 DS3/
E3/STS-1 LIU IC (one channel shown) ............................................................................................... 130
3.1 B
IT
-F
IELDS
WITHIN
THE
L
INE
I
NTERFACE
D
RIVE
R
EGISTER
.................................................................................. 130
LINE INTERFACE DRIVE R
EGISTER
(A
DDRESS
= 0
X
80) ..................................................................... 130
T
ABLE
15: T
HE
R
ELATIONSHIP
BETWEEN
THE
STATES
OF
RLOOP, LLOOP
AND
THE
RESULTING
LOOP
-
BACK
MODE
WITH
THE
XRT7300
DEVICE
.................................................................................................................. 132
3.2 B
IT
-F
IELDS
WITHIN
THE
L
INE
I
NTERFACE
S
CAN
R
EGISTER
................................................................................... 132
LINE INTERFACE
S
CAN R
EGISTER
(A
DDRESS
= 0
X
81) ...................................................................... 133
XRT72L50 CONFIGURATION ..................................................................................... 135
4.0 DS3 Operation of the XRT72L50 ...................................................................................................... 135
F
RAMER
O
PERATING
M
ODE
R
EGISTER
(A
DDRESS
= 0
X
00) ..................................................................... 135
4.1 D
ESCRIPTION
OF
THE
DS3 F
RAMES
AND
A
SSOCIATED
O
VERHEAD
B
ITS
.............................................................. 135
Figure 40. DS3 Frame Format for C-bit Parity ................................................................................... 135
Figure 41. DS3 Frame Format for M13 .............................................................................................. 136
F
RAMER
O
PERATING
M
ODE
R
EGISTER
(A
DDRESS
= 0
X
00) ..................................................................... 136
T
ABLE
16: T
HE
R
ELATIONSHIP
BETWEEN
THE
CONTENT
OF
B
IT
2, (C-B
IT
P
ARITY
*/M13)
WITHIN
THE
F
RAMER
O
P
-
ERATING
M
ODE
R
EGISTER
AND
THE
RESULTING
DS3 F
RAMING
F
ORMAT
................................................. 137
T
ABLE
17: C-
BIT
F
UNCTIONS
FOR
THE
C-
BIT
P
ARITY
DS3 F
RAME
F
ORMAT
............................................ 137
4.1.1 Frame Synchronization Bits (Applies to both M13 and C-bit Parity Framing Formats) ......................... 137
4.1.2 Performance Monitoring/Error Detection Bits (Parity) .......................................................................... 138
4.1.3 Alarm and Signaling-Related Overhead Bits ......................................................................................... 138
Valid M-bits, F-bits, and P-bits ........................................................................................ 138
4.1.4 The Data Link Related Overhead Bits ................................................................................................... 139
4.2 T
HE
T
RANSMIT
S
ECTION
OF
THE
XRT72L50 (DS3 M
ODE
O
PERATION
) ............................................................... 139
Figure 42. A Simple Illustration of the Transmit Section, within the XRT72L50, when it has been configured
to operate in the DS3 Mode ................................................................................................................ 140
4.2.1 The Transmit Payload Data Input Interface Block ................................................................................. 140
Figure 43. A Simple Illustration of the Transmit Payload Data Input Interface Block ......................... 141
T
ABLE
18: L
ISTING
AND
D
ESCRIPTION
OF
THE
PINS
ASSOCIATED
WITH
THE
T
RANSMIT
P
AYLOAD
D
ATA
I
NPUT
I
N
-
TERFACE
............................................................................................................................................... 142
Figure 44. Illustration of the Terminal Equipment being interfaced to the Transmit Payload Data Input Inter-
face block (of the XRT72L50) for Mode 1(Serial/Loop-Timing) Operation .......................................... 144
Figure 45. Behavior of the Terminal Interface signals between the Transmit Payload Data Input Interface
block of the XRT72L50 and the Terminal Equipment (for Mode 1 Operation) .................................... 145
F
RAMER
O
PERATING
M
ODE
R
EGISTER
(A
DDRESS
= 0
X
00) ..................................................................... 145
Figure 46. Illustration of the Terminal Equipment being interfaced to the Transmit Payload Data Input Inter-
face block of the XRT72L50 for Mode 2 (Serial/Local-Timed/Frame-Slave) Operation ...................... 146
Figure 47. Behavior of the Terminal Interface signals between the XRT72L50 and the Terminal Equipment
(Mode 2 Operation) ............................................................................................................................. 147