XRT74L73 Datasheet, PDF (422/488 Pages) Exar Corporation – 3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER

XRT74L73
3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
REV. P1.0.1
PRELIMINARY
The user can exercise each of these options by writ- Register (Address = 0x30). The bit format of this reg-
ing the appropriate data to the Tx E3 Configuration
ister is presented below.
TXE3 CONFIGURATION REGISTER (ADDRESS = 0X30)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
Not Used
TxDL
in NR
Not Used
RO
RO
RO
R/W
RO
0
0
0
0
0
BIT 2
TxAIS
Enable
R/W
0
BIT 1
TxLOS
Enable
R/W
0
BIT 0
TxMARx
R/W
0
Bit-field 2 through 0 permit the user to transmit vari-
ous alarm conditions to the remote terminal equip-
ment. The role/function of each of these three bit-
fields within the register, are discussed below.
6.2.4.2.1.1 Tx AIS Enable - Bit 2
This read/write bit field permits the user to force the
transmission of an AIS (Alarm Indication Signal) pat-
tern to the remote terminal equipment via software
control. If the user opts to transmit an AIS pattern,
then the Transmit Section of the Framer IC will begin
to transmit an unframed all ones pattern to the re-
mote terminal equipment. Table 94 presents the re-
lationship between the contents of this bit-field, and
the resulting Framer action.
TABLE 94: THE RELATIONSHIP BETWEEN THE CONTENTS OF BIT 2 (TX AIS ENABLE) WITHIN THE TX E3
CONFIGURATION REGISTER, AND THE RESULTING TRANSMIT E3 FRAMER BLOCK’S ACTION
BIT 2
0
1
TRANSMIT E3 FRAMER’S ACTION
Normal Operation:
The Transmit Section of the XRT74L73 Framer IC will transmit E3 traffic based upon data that it accepts via
the Transmit Payload Data Input Interface block, the Transmit Overhead Data Input Interface block, the Trans-
mit HDLC Controller block and internally generated overhead bytes.
Transmit AIS Pattern:
The Transmit E3 Framer block will overwrite the E3 traffic, within an Unframed All Ones pattern.
NOTE: This bit is ignored whenever the TxLOS bit-field is
set.
6.2.4.2.1.2 Transmit LOS Enable - Bit 1
This read/write bit field allows the user to transmit an
LOS (Loss of Signal) pattern to the remote terminal,
upon software control. Table 95 relates the contents
of this bit field to the Transmit E3 Framer block’s ac-
tion.
TABLE 95: THE RELATIONSHIP BETWEEN THE CONTENTS OF BIT 1 (TX LOS) WITHIN THE TX E3 CONFIGURATION
REGISTER, AND THE RESULTING TRANSMIT E3 FRAMER BLOCK’S ACTION
BIT 1
0
1
TRANSMIT E3 FRAMER’S ACTION
Normal Operation:
The Overhead bits are either internally generated, or they are inserted via the Transmit Overhead Data Input
Interface or the Transmit HDLC Controller blocks. The Payload bits are received from the Transmit Payload
Data Input Interface.
Transmit LOS Pattern:
When this command is invoked the Transmit E3 Framer will do the following.
• Set all of the overhead bytes to "0" (including the FA1 and FA2 bytes)
Overwrite the E3 payload bits with an "all zeros" pattern.
NOTE: When this bit is set, it overrides all of the other bits in
this register.
6.2.4.2.1.3 TxMARx - Bit 0
423