XR72L52 Datasheet, PDF (404/480 Pages) Exar Corporation – TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L52
REV. 1.0.1
xr
TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
• 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 XRT72L52).
• 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 Regis-
ter (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 Trans-
mit Section of the Framer IC will begin to transmit an unframed all ones pattern to the remote terminal equip-
ment. Table 75 presents the relationship between the contents of this bit-field, and the resulting Framer action.
TABLE 75: 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 XRT72L52 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
388