
PEB 2255
FALC-LH V1.3
Functional Description E1
Data Sheet
8
0
2000-07
Similar to the receive line interface three different data types are supported:
Ternary Signal
Single rail data is converted into a ternary signal which is output on pins
X
L1 and
X
L2.
The HDB3 and AMI line code is employed. Selected by FMR0.
X
C1/0 and
LIM1.DRS
=
0.
Dual rail data PCM(
+
), PCM(–) at multifunction ports
X
DOP/
X
DON with 50
%
or
100
%
duty cycle and with programmable polarity. Line coding is done in the same
way as in the ternary interface. Selected by FMR0.
X
C1/0 and LIM1.DRS
=
1.
U
nipolar data on port
X
OID is transmitted either in NR
Z
(Non Return to
Z
ero) with
100
%
duty cycle or in CMI (Code Mark Inversion or known as 1T2B) Code with or
without (FMR3.CMI) preprocessed HDB3 coding to a fibre optical interface. Clocking
off data is done with the rising edge of the transmit clock
X
CL
K
(20
48
kHz) and with
a programmable polarity. Selection is done by FMR0.
X
C1
=
0 and LIM1.DRS
=
1.
4.3.5
Programmable Pulse Shaper (E1)
The analog transmitter includes a programmable pulse shaper to satisfy the
requirements of IT
U
-T I.
4
31. The amplitude and shape of the transmit pulses are
completely programmable via registers
X
PM0...2 from the microprocessor interface.
The transmitter requires an external step up transformer to drive the line.
4.3.6
Transmit Line Monitor (E1)
The transmit line monitor compares the transmit line pulses on
X
L1 and
X
L2 with the
transmit input signals received on pins
X
L1M and
X
L2M. The monitor detects faults on
the primary side of the transformer and protects the device from damage by setting the
transmit lines into high impedance state automatically. Faults on the secondary side can
not be detected. To detect shorts, the configuration shown in
Figure 24
must be
provided and the default (reset) value of registers
X
PM0...2 must be selected. Otherwise
a short detection can not be guaranteed. Two conditions are detected by the monitor:
“Transmit Line Ones Density“ (more than 31 consecutive zeroes) and “Transmit Line
Shorted“. In both cases a transmit line monitor status change interrupt is provided.