XRT74L74 Datasheet, PDF (256/498 Pages) Exar Corporation – 4 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER

XRT74L74
REV. P1.1.1
4 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
ADVANCED CONFIDENTIAL
RX DS3 CONFIGURATION AND STATUS REGISTER, (ADDRESS = 0X10)
BIT 7
BIT 6
BIT 5
BIT 4
R/O
R/O
R/O
R/O
X
X
X
X
• The Receive DS3 Framer block will also issue a
Change in OOF Status interrupt request, anytime
there is a change in the OOF status.
5.3.2.3 Forcing a Reframe via Software Com-
mand
The Framer IC permits the user to force a reframe
procedure of the Receive DS3 Framer block via soft-
ware command. If a "1" is written into Bit 0 of the I/O
I/O CONTROL REGISTER (ADDRESS = 0X01)
BIT 3
BIT2
BIT 1
BIT 0
R/W
R/W
R/W
R/W
X
X
X
X
Control Register, as depicted below, then the Receive
DS3 Framer will be forced into the Frame Acquisition
Mode, (or more specifically, in the F-Bit Search State
per Figure 88). Afterwards, the Receive DS3 Framer
block will begin its search for valid F-Bits. The Fram-
er IC will also respond to this command by asserting
the RxOOF output pin, and generating a Change in
OOF Status interrupt.
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT2
BIT 1
BIT 0
Disable
TxLOC
R/W
1
LOC
RO
0
Disable
RxLOC
R/W
1
AMI/ZeroSup*
R/W
0
Unipolar/
Bipolar*
R/W
0
TxLine CLK
Invert
R/W
0
RxLine CLK
Invert
R/W
0
Reframe
R/W
1
5.3.2.4 Performance Monitoring of the Receive
DS3 Framer block
The user can monitor the number of framing bit errors
(M and F bits) that have been detected by the Re-
ceive DS3 Framer block. This is accomplished by pe-
riodically reading the PMON Framing Bit Error Count
Registers (Address = 0x52 and 0x53), as depicted
below.
PMON FRAMING BIT ERROR EVENT COUNT REGISTER - MSB (ADDRESS = 0X52)
BIT 7
RUR
1
BIT 6
RUR
0
BIT 5
RUR
1
BIT 4
BIT 3
F-Bit Error Count - High Byte
RUR
RUR
0
0
BIT2
RUR
0
BIT 1
RUR
0
BIT 0
RUR
0
PMON FRAMING BIT ERROR EVENT COUNT REGISTER - LSB (ADDRESS = 0X53)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT2
BIT 1
BIT 0
RUR
0
RUR
0
RUR
0
F-Bit Error Count - Low Byte
RUR
RUR
0
0
RUR
0
RUR
0
RUR
0
When the µP/µC reads these registers, it will read in
the number of framing bit errors that have been de-
tected since the last read of these two registers.
These registers are reset upon read.
5.3.2.5 DS3 Receive Alarms
The Receive DS3 Framer block is capable of detect-
ing any of the following alarm conditions.
• LOS (Loss of Signal)
• AIS (Alarm Indication Signal)
• The Idle Pattern.
• FERF (Far-End Receive Failure) of Yellow Alarm
condition.
• FEBE (Far-End-Block Error)
• Change in AIC State
The methods by which the Receive DS3 Framer block
uses to detect and declare each of these alarm condi-
tions are described below.
5.3.2.5.1 The Loss of Signal (LOS) Alarm
The Receive DS3 Framer block will declare a Loss of
Signal (LOS) state when it detects 180 consecutive
254