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IDT82P2281
SINGLE T1/E1/J1 LONG HAUL / SHORT HAUL TRANSCEIVER
60
October 7, 2003
3.18
TRANSMIT SYSTEM INTERFACE
The Transmit System Interface determines how to input the data to
the device. The timing clocks and framing pulses can be provided by the
system backplane or obtained from the processed data. The Transmit
System Interface supports various configurations to meet various
requirements in different applications.
3.18.1
T1/J1 MODE
In T1/J1 mode, the Transmit System Interface can be set in Non-
multiplexed Mode or Multiplexed Mode. In the Non-multiplexed Mode,
the TSD pin is used to input the data at the bit rate of 1.544 Mb/s or
2.048 Mb/s (T1/J1 mode E1 rate). While in the Multiplexed Mode, the
data is byte-interleaved from one high speed data stream and inputs on
the MTSD pin at the bit rate of 8.192 Mb/s. The demultiplexed data input
to the link is 2.048 Mb/s on the system side and converted into 1.544
Mb/s format to the device.
In the Non-multiplexed mode, if the transmit system interface and
the transmit line side are timed to a same clock source, the Transmit
System Interface is in Transmit Clock Master mode. If the transmit sys-
tem interface and the transmit line side are timed to different clock
sources, the Transmit System Interface is in Transmit Clock Slave
mode.
In the Transmit Clock Master mode, if TSCK outputs pulses during
the entire T1/J1 frame, the Transmit System Interface is in Transmit
Clock Master Full T1/J1 mode. If only the clocks aligned to the selected
channels are output on TSCK, the Transmit System Interface is in
Transmit Clock Master Fractional T1/J1 mode.
In the Transmit Clock Slave mode, the backplane data rate may be
equal to 1.544 Mb/s (i.e., the line data rate) or 2.048 Mb/s. If the back-
plane data rate is 2.048 Mb/s, the Transmit System Interface is in T1/J1
mode E1 rate and the data to be transmitted should be mapped to 1.544
Mb/s per 3 kinds of schemes.
In the Transmit Multiplexed mode, since the demultiplexed data
rate on the system side (2.048 Mb/s) should be mapped to the data rate
in the line side (1.544 Mb/s), there are still 3 kinds of schemes to be
selected.
Table 42 summarizes how to set the transmit system interface into
various operating modes and the pins’ direction of the transmit system
interface in different operating modes.
3.18.1.1
Transmit Clock Master Mode
In the Transmit Clock Master mode, the timing signal on the TSCK
pin and framing pulse on the TSFS pin are used to input the data on the
TSD pin. The signaling bits on the TSIG pin are per-channel aligned with
the data on the TSD pin.
In the Transmit Clock Master mode, the data on the system inter-
face is clocked by the TSCK. The active edge of the TSCK used to
update the pulse on the TSFS is determined by the FE bit. The active
edge of the TSCK used to sample the data on the TSD and TSIG is
determined by the DE bit. If the FE bit and the DE bit are not equal, the
pulse on the TSFS is ahead.
In the Transmit Clock Master mode, the TSFS can indicate each F-
bit or the first F-bit of every SF/ESF/T1 DM/SLC-96 multi-frame. The
indications are selected by the FSTYP bit. The active polarity of the
TSFS is selected by the FSINV bit.
The Transmit Clock Master mode includes two sub-modes: Trans-
mit Clock Master Full T1/J1 mode and Transmit Clock Master Fractional
T1/J1 mode.
3.18.1.1.1
Besides all the common functions described in the Transmit Clock
Master mode, the special feature in this mode is that the TSCK is a stan-
dard 1.544 MHz clock, and the data in the F-bit and all 24 channels in a
standard T1/J1 frame are clocked in by the TSCK.
Transmit Clock Master Full T1/J1 Mode
Table 42: Operating Modes Selection In T1/J1 Transmit Path
TMUX TMODEGFBITGAP
MAP[1:0]
2
Operating Mode
Transmit System Interface Pin
Input
Output
0
0
00 / 0
not all 0s
1
X
Transmit Clock Master Full T1/J1
Transmit Clock Master Fractional T1/J1
TSD, TSIG
TSCK, TSFS
1
X
00
01
Transmit Clock Slave - T1/J1 Rate
Transmit Clock Slave - T1/J1 Mode E1 Rate per G.802
Transmit Clock Slave - T1/J1 Mode E1 Rate per One Filler Every
Four CHs
Transmit Clock Slave - T1/J1 Mode E1 Rate per Continuous CHs
Transmit Multiplexed - T1/J1 Mode E1 Rate per G.802
Transmit Multiplexed - T1/J1 Mode E1 Rate per One Filler Every
Four CHs
Transmit Multiplexed - T1/J1 Mode E1 Rate per Continuous CHs
TSD, TSIG, TSCK, TSFS
X
10
11
01
1
X
X
MTSCK, MTSFS, MTSD,
MTSIG
X
10
11
NOTE:
1. When the G56K, GAP bits in TPLC indirect registers are set, the PCCE bit must be set to ‘1’.
2. The MAP[1:0] bits can not be set to ‘00’ in the Transmit Multiplexed mode.