XRT84L38 View Datasheet(PDF) - Exar Corporation
Part Name
Description
MFG CO.
'XRT84L38' PDF : 453 Pages View PDF
XRT84L38
OCTAL T1/E1/J1 FRAMER
REV. 1.0.1
BIT NUMBER
5-4
BIT NAME
Yellow Alarm Generation
Select
BIT TYPE
BIT DESCRIPTION
R/W Yellow Alarm Generation Select:
These READ/WRITE bit-fields activate and de-activate transmis-
sion of Yellow Alarm by the framer. In various framing formats,
the pattern and duration of Yellow Alarm various. The following
text describes how the framer transmits Yellow Alarm by setting
these bit-fields to different values.
SF Mode:
When these bits are set to 00:
Transmission of Yellow Alarm is disabled.
When these bits are set to 01:
The framer transmits Yellow Alarm by converting the second
MSB of all outgoing twenty-four DS0 channel into zero.
When these bits are set to 10:
The framer transmits Yellow Alarm by sending the Super-frame
Alignment Bit (Fs) of Frame 12 as one.
When these bits are set to 11:
The framer transmits Yellow Alarm by converting the second
MSB of all outgoing twenty-four DS0 channel into zero.N Mode:
When these bits are set to 00:
Transmission of Yellow Alarm is disabled.
When these bits are set to 01, 10 or 11:
The framer transmits Yellow Alarm by converting the second
MSB of all outgoing twenty-four DS0 channel into zero.
ESF Mode:
When the framer is in ESF mode, it transmits Yellow Alarm pat-
tern of eight ones followed by eight zeros
(1111_1111_0000_0000) through the 4Kbit/s data link bits.
When the Yellow Alarm Generation Select bits are set to 00:
Transmission of Yellow Alarm is disabled.
When these bits are set to 01:
The following scenario will happen:
1. If Bit 0 of Yellow Alarm Generation Select forms a pulse
width shorter or equal to the time required to transmit 255
patterns on the 4Kbit/s data link, the alarm is transmitted for
255 patterns.
2. If Bit 0 of Yellow Alarm Generation Select forms a pulse
width longer than the time required to transmit 255 patterns
on the 4Kbit/s data link, the alarm continues until Bit 0 goes
LOW.
3. A second pulse on Bit 0 of Yellow Alarm Generation Select
during an alarm transmission resets the pattern counter.
The framer will send another 255 patterns of the Yellow
Alarm.
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