XRT74L73
3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
REV. P1.0.1
PRELIMINARY
429
Table 97 relates the content of this bit-field to the Bi-
polar Line Code which E3 Data will be transmitted
and received at.
N
OTES
:
1. This bit is ignored if the Unipolar mode is selected.
2. This selection also effects the operation of the
Receive E3 LIU Interface block
6.2.5.2
TxLineClk Clock Edge Selection
The Framer also allows the user to specify whether
the E3 output data (via TxPOS and/or TxNEG output
pins) is to be updated on the rising or falling edges of
the TxLineClk signal. This selection is made by writ-
ing to bit 2 of the I/O Control Register, as depicted be-
low.
Table 98 relates the contents of this bit field to the
clock edge of TxClk that E3 Data is output on the Tx-
POS and/or TxNEG output pins.
N
OTE
:
The user will typically make the selection based
upon the set-up and hold time requirements of the Transmit
LIU IC.
I/O CONTROL REGISTER (ADDRESS = 0X01)
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
97: T
HE
R
ELATIONSHIP
BETWEEN
B
IT
4 (AMI/
HDB3*)
WITHIN
THE
I/O C
ONTROL
R
EGISTER
AND
THE
B
IPOLAR
L
INE
C
ODE
THAT
IS
OUTPUT
BY
THE
T
RANSMIT
E3 LIU I
NTERFACE
B
LOCK
B
IT
4
B
IPOLAR
L
INE
C
ODE
0
HDB3
1
AMI
II/O CONTROL REGISTER (ADDRESS = 0X01)
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
98: T
HE
R
ELATIONSHIP
BETWEEN
THE
CONTENTS
OF
B
IT
2 (T
X
L
INE
C
LK
I
NV
)
WITHIN
THE
I/O C
ONTROL
R
EGISTER
AND
THE
T
X
L
INE
C
LK
CLOCK
EDGE
THAT
T
X
POS
AND
T
X
NEG
ARE
UPDATED
ON
B
IT
2
R
ESULT
0
Rising Edge:
Outputs on TxPOS and/or TxNEG are updated on the rising edge of TxLineClk.
See Figure 190 for timing relationship between TxLineClk, TxPOS and TxNEG signals, for this selection.
Falling Edge:
Outputs on TxPOS and/or TxNEG are updated on the falling edge of TxLineClk.
See Figure 191 for timing relationship between TxLineClk, TxPOS and TxNEG signals, for this selection.
1