XRT72L50 Datasheet, PDF (396/471 Pages) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
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In addition to taking data from multiple sources and multiplexing them, in appropriate manner, to create the
Outbound E3 frames, the Transmit E3 Framer block has the following roles.
• Generating Alarm Conditions
• Generating Errored Frames (for testing purposes)
• Routing Outbound E3 frames to the Transmit E3 LIU Interface block
Each of these additional roles are discussed below.
6.2.4.2.1
Generating Alarm Conditions
The Transmit E3 Framer block permits the user to, by writing the appropriate data into the on-chip registers, to
override the data that is being written into the Transmit Payload Data and Overhead Data Input Interfaces and
transmit the following alarm conditions.
• Generate the Yellow Alarms (or FERF indicators)
• Manipulate the FERF-bit, within the MA byte (set them to "0")
• Generate the AIS Pattern
• Generate the LOS pattern
• Generate FERF (Yellow) Alarms, in response to detection of a Red Alarm condition (via the Receive Section
of the XRT72L50).
• Generate and transmit a desired value for the FEBE (Far-End-Block Error) bit, within the MA byte.
The procedure and results of generating any of these alarm conditions is presented below.
The user can exercise each of these options by writing the appropriate data to the Tx E3 Configuration
Register (Address = 0x30). The bit format of this register is presented below.
TxE3 Configuration Register (Address = 0x30)
BIT 7
RO
0
BIT 6
Not Used
RO
0
BIT 5
RO
0
BIT 4
TxDL
in NR
R/W
0
BIT 3
Not Used
RO
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 various alarm conditions to the remote terminal equipment.
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) pattern 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 remote terminal
equipment. Table 75 presents the relationship between the contents of this bit-field, and the resulting Framer
action.
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