xr
PRELIMINARY
XRT86VL38
REV. P1.0.6
OCTAL T1/E1/J1 FRAMER/LIU COMBO
348
special line build out, see the arbitrary pulse section of this datasheet. The short haul LBO settings are shown
in Table 184
7.3.1
Arbitrary Pulse Generator
In T1 mode only, the arbitrary pulse generator divides the pulse into eight individual segments. Each segment
is set by a 7-Bit binary word by programming the appropriate channel register. This allows the system
designer to set the overshoot, amplitude, and undershoot for a unique line build out. The MSB (bit 7) is a sign-
bit. If the sign-bit is set to "0", the segment will move in a positive direction relative to a flat line (zero)
condition. If this sign-bit is set to "1", the segment will move in a negative direction relative to a flat line
condition. The resolution of the DAC is typically 60mV per LSB. Thus, writing 7-bit = 1111111 will clamp the
output at either voltage rail corresponding to a maximum amplitude. A pulse with numbered segments is
shown in Figure 59.
N
OTE
: By default, the arbitrary segments are programmed to 0x00h. The transmitter outputs will result in an all zero
pattern to the line interface.
7.3.2
DMO (Digital Monitor Output)
The driver monitor circuit is used to detect transmit driver failures by monitoring the activities at TTIP/TRING
outputs. Driver failure may be caused by a short circuit in the primary transformer or system problems at the
transmit inputs. If the transmitter of a channel has no output for more than 128 clock cycles, DMO goes "High"
until a valid transmit pulse is detected. If the DMO interrupt is enabled, the change in status of DMO will cause
the interrupt pin to go "Low". Once the status register is read, the interrupt pin will return "High" and the status
register will be reset (RUR).
T
ABLE
184: S
HORT
H
AUL
L
INE
B
UILD
O
UT
LBO
SETTING
EQC[4:0]
R
ANGE
OF
C
ABLE
A
TTENUATION
08h (01000)
0 - 133 Feet
09h (01001)
133 - 266 Feet
0Ah (01010)
266 - 399 Feet
0Bh (01011)
399 - 533 Feet
0Ch (01100)
533 - 655 Feet
F
IGURE
59. A
RBITRARY
P
ULSE
S
EGMENT
A
SSIGNMENT
1
2
3
4
5
6
7
8
Segment
Register
1
0x0Fn8
2
0x0Fn9
3
0x0Fna
4
0x0Fnb
5
0x0Fnc
6
0x0Fnd
7
0x0Fne
8
0x0Fnf