XRT74L73
3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
REV. P1.0.1
PRELIMINARY
437
6.3.1.2.3
The Receive E3 LIU Interface block will also check
the incoming E3 data stream for line code violations.
For example, when the Receive E3 LIU Interface
block detects a valid bipolar violation (e.g., in HDB3
line code), it will substitute four zeros into the binary
data stream. However, if the bipolar violation is in-
valid, then an LCV (Line Code Violation) is flagged
and the PMON LCV Event Count Register (Address =
0x50 and 0x51) will also be incremented. Additional-
ly, the LCV-One-Second Accumulation Registers
(Address = 0x6E and 0x6F) will be incremented. For
example: If the incoming E3 data is HDB3 encoded,
the Receive E3 LIU Interface block will also incre-
II/O CONTROL REGISTER (ADDRESS = 0X01)
Line Code Violations
ment the LCV One-Second Accumulation Register if
three (or more) consecutive zeros are received.
6.3.1.2.4
RxLineClk Clock Edge Selection
The incoming unipolar or bipolar data, applied to the
RxPOS and the RxNEG input pins are clocked into
the Receive E3 LIU Interface block via the RxLineClk
signal. The Framer IC 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 Framer IC. The us-
er can make this selection by writing the appropriate
data to bit 1 of the I/O Control Register, as depicted
below.
Table 100 depicts the relationship between the value
of this bit-field to the sampling clock edge of RxLi-
neClk.
Figure 198 and Figure 199 present the Waveform
and Timing Relationships between RxLineClk, Rx-
POS and RxNEG for each of these configurations.
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Disable
TxLOC
LOC
Disable
RxLOC
AMI/ZeroSup*
Unipolar/
Bipolar*
TxLine CLK
Invert
RxLine CLK
Invert
Reframe
R/W
RO
R/W
R/W
R/W
R/W
R/W
R/W
1
0
1
0
0
0
0
0
T
ABLE
100: T
HE
R
ELATIONSHIP
BETWEEN
THE
CONTENTS
OF
B
IT
1 (R
X
L
INE
C
LK
I
NV
)
OF
THE
I/O C
ONTROL
R
EGISTER
,
AND
THE
SAMPLING
EDGE
OF
THE
R
X
L
INE
C
LK
SIGNAL
R
X
CLKI
NV
(B
IT
1)
R
ESULT
0
.Rising Edge:
RxPOS and RxNEG are sampled at the rising edge of RxLineClk. See Figure 198 for timing relationship
between RxLineClk, RxPOS, and RxNEG.
Falling Edge:
RxPOS and RxNEG are sampled at the falling edge of RxLineClk. See Figure 199 for timing relationship
between RxLineClk, RxPOS, and RxNEG.
1