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PRELIMINARY
DS3 UNI FOR ATM
XRT7245
REV. 1.03
225
The Receive DS3 Framer will also issue a “Change
in OOF Status” interrupt request, anytime there is a
change in the “OOF” status.
7.1.2.2.3
Forcing a Reframe via Software
Command
The UNI allows the user to command a reframe pro-
cedure with the Receive DS3 Framer via software
command. If the user writes a “1” into Bit 0 of the UNI
I/O 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 68) and will begin its search
for valid F-Bits. The UNI will also respond to this
command by asserting the RxOOF output pin, and
generating a “Change in OOF Status” interrupt.
7.1.2.2.4
Performance Monitoring of the Frame
Synchronization section of the
Receive DS3 Framer
The user can monitor the number of framing bit
errors (M and F bits) that have been detected by the
Receive DS3 Framer. This is accomplished by peri-
odically reading the PMON Framing Bit Error Count
Registers (Address = 22h and 23h), as depicted below.
When the local μP/μC reads these registers, it will
read in the number of framing bit errors that have
been detected since the last read of these two regis-
ters. These registers are reset upon read.
7.1.2.3
DS3 Receive Alarms
7.1.2.3.1
The Receive DS3 Framer will declare a “Loss of Signal”
(LOS) state when it detects 180 consecutive incom-
Loss of Signal (LOS) Alarm
ing “0s” via the RxPOS and RxNEG input pins or if
the RLOS input pin (from the XRT7295 DS3 Line Re-
ceiver IC) is asserted. The Receive DS3 Framer will
indicate the occurrence of an LOS condition by:
Asserting the RxLOS output pin (e.g., toggles it
“high”).
Setting Bit 6 of the Rx DS3 Configuration and Status
Register to “1”, as depicted below.
UNI I/O Control Register (Address = 01h)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
LOC Enable
Test PMON
IntEn Reset
AMI
Unipolar
TxClk Inv
RxClk Inv
Reframe
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Address = 22h, PMON Framing Bit Error Event Count Register—MSB
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
F-Bit Error Count—High Byte
RO
RO
RO
RO
RO
RO
RO
RO
0
0
0
0
0
0
0
0
Address = 23h, PMON Framing Bit Error Event Count Register—LSB
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
F-Bit Error Count—Low Byte
RO
RO
RO
RO
RO
RO
RO
RO
0
0
0
0
0
0
0
0
Rx DS3 Configuration and Status Register, (Address = 0Eh)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Rx AIS
Rx LOS
Rx Idle
Rx OOF
Int LOS Disable
Framing on Parity
F-Sync Algo
M-Sync Algo
X
1
X
X
X
X
X
X