XRT7245
DS3 UNI FOR ATM
á
PRELIMINARY
REV. 1.03
220
7.1.2.1.2.3
The Receive DS3 Framer will also check the incoming
DS3 data stream for line code violations. For example,
when the Receive DS3 Framer detects a valid bipolar
violation (e.g., in B3ZS line code), it will substitute
three zeros into the binary data stream. However, if
the bipolar violation is invalid, then an LCV (Line Code
Violation) is flagged and the PMON LCV Event Count
Register (Address = 20h and 21h) is incremented.
Additionally, the LCV-One Second Accumulation
Registers will be incremented. For example: if the
incoming DS3 data is B3ZS encoded, the Receive
DS3 Framer will also increment the LCV One Second
Line Code Violations
Accumulation Register if three (or more) consecutive
zeros are received.
7.1.2.1.2.4
The incoming unipolar or bipolar data, applied to the
RxPOS and the RxNEG input pins are clocked into
the Receive DS3 Framer via the RxLineClk signal.
The UNI allows the user to specify which edge (e.g,
rising or falling) of the RxLineClk signal will sample
and latch the signal at the RxPOS and RxNEG input
signals into the UNI. The user can make this selection
by writing the appropriate data to bit 1 of the UNI I/O
Control Register, as depicted below.
Receive Line Input Clocking
The following table depicts the relationship between
the value of this bit-field to the sampling clock edge of
RxLineClk.
Figure 66 and 67 presents the Waveform and Timing
Relationships between RxLineClk, RxPOS and RxNEG
for each of these configurations.
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/B3ZS*
Unipolar/
Bipolar*
TxLine
Clk Inv
RxLine
Clk Inv
Reframe
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
T
ABLE
45: T
HE
R
ELATIONSHIP
BETWEEN
THE
CONTENTS
OF
B
IT
1 (R
X
L
INE
C
LK
I
NV
)
OF
THE
UNI I/O C
ONTROL
R
EGISTER
,
AND
THE
SAMPLING
EDGE
OF
THE
R
X
L
INE
C
LK
SIGNAL
R
X
C
LK
I
NV
(B
IT
1)
R
ESULT
0
Rising Edge:
RxPOS and RxNEG are sampled at the rising edge of RxLineClk. See Figure 66 for
timing relationship between RxLineClk, RxPOS, and RxNEG.
1
Falling Edge:
RxPOS and RxNEG are sampled at the falling edge of RxLineClk. See Figure 67 for
timing relationship between RxLineClk, RxPOS, and RxNEG.