XRT72L13 Datasheet, PDF (284/370 Pages) Exar Corporation – M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC

XRT72L13
M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC
REV. P1.0.6
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PRELIMINARY
"Transmit Payload Data" and "Overhead Data Input
Interfaces" and transmit the following alarm condi-
tions.
• Generate the Yellow Alarms (or "FERF" indicators)
• Generate and transmit a desired value for FEBE
(Far-End-Block Error).
The procedure and results of generating any of these
alarm conditions is presented below.
• Manipulate the X-bit (set them to "1")
• Generate the AIS Pattern
• Generate the IDLE pattern
• Generate the LOS pattern
The user can exercise each of these options by writ-
ing the appropriate data to the Tx DS3 Configuration
Register (Address = 0x30). The bit format of this reg-
ister is presented below.
• Generate FERF (Yellow) Alarms, in response to
detection of a "Red Alarm" condition (via the
Receive Section of the XRT72L13).
TX DS3 CONFIGURATION REGISTER (ADDRESS = 0X30)
BIT 7
Tx
Yellow Alarm
R/W
0
BIT 6
Tx X-Bit
R/W
0
BIT 5
Tx IDLE
Pattern
R/W
1
BIT 4
Tx AIS
Pattern
R/W
0
BIT 3
Tx LOS
Pattern
R/W
1
BIT2
FERF on
LOS
R/W
0
BIT 1
FERF on
OOF
R/W
1
BIT 0
FERF on
AIS
R/W
1
The role/function of each of these bit-fields within the
register, are discussed below.
4.2.4.2.1.1 Transmit Yellow Alarm - Bit 7
This "read/write" bit field permits the user to force the
transmission of a "Yellow Alarm" to the "remote ter-
minal equipment" via software control. If the user
opts to transmit a "Yellow Alarm" then both of the X-
bits, within the "outbound" DS3 frames will be set to
'0'. Table 21 relates the content of this bit field to the
Transmit DS3 Framer block's action.
TABLE 21: THE RELATIONSHIP BETWEEN THE CONTENTS OF BIT 7 (TX YELLOW ALARM) WITHIN THE TX DS3
CONFIGURATION REGISTER, AND THE RESULTING TRANSMIT DS3 FRAMER BLOCK'S ACTION
BIT 7
0
1
TRANSMIT DS3 FRAMER'S ACTION
Normal Operation:
The X-bits are generated by the Transmit DS3 Framer block based upon "Near End" Receiving Conditions"
(as detected by the Receive Section of the chip)
Transmit Yellow Alarm:
The Transmit DS3 Framer block will overwrite the X-bits by setting them all to "0". The payload information is
not modified and is transmitted as normal.
NOTE: This bit is ignored when either the "TxIDLE",
"TxAIS", or the "TxLOS" bit-fields are set.
4.2.4.2.1.2 Transmit X-bit - Bit 6
This bit field functions as the logical complement to
Bit 7 (e.g., "Tx Yellow Alarm). This "read/write" bit
field permits the user to force all of the X-bits, in the
"outbound" DS3 frames, to "1" and transmit them to
the "remote terminal equipment". Table 22 relates
the content of this bit field to the Transmit DS3 Framer
Block's action.
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