IDT82P2284
QUAD T1/E1/J1 LONG HAUL / SHORT HAUL TRANSCEIVER
Functional Description
77
February 25, 2008
3.17.2 E1 MODE
In E1 mode, the Receive System Interface can be set in Non-multi-
plexed Mode or Multiplexed Mode. In the Non-multiplexed Mode, the
RSDn pin is used to output the received data from each link at the bit
rate of 2.048 Mb/s. While in the Multiplexed Mode, the received data
from the four links is byte interleaved to form one high speed data
stream and output on the MRSDA1 (MRSDB1) pins at the bit rate of
8.192 Mb/s.
In the Non-multiplexed mode, if the RSCK is from outside, the
receive system interface is in Receive Clcok Slave mode, otherwise if
the device outputs RSCK, the receive system interface is in Receive
Clcok Master mode.
In the Receive Clock Master mode, if RSCKn outputs pulses during
the entire E1 frame, the Receive System Interface is in Receive Clock
Master Full E1 mode. If only the clocks aligned to the selected timeslots
are output on RSCKn, the Receive System Interface is in Receive Clock
Master Fractional E1 mode.
Table 40 summarizes how to set the receive system interface of each
link into various operating modes and the pins’ direction of the receive
system interface in different operating modes.
3.17.2.1 Receive Clock Master Mode
In the Receive Clock Master mode, each link uses its own timing
signal on the RSCKn pin and framing pulse on the RSFSn pin to output
the data on each RSDn pin. The signaling bits on the RSIGn pin are per-
timeslot aligned with the data on the RSDn pin.
In the Receive Clock Master mode, the data on the system interface
is clocked by the RSCKn. The active edge of the RSCKn used to update
the pulse on the RSFSn is determined by the FE bit. The active edge of
the RSCKn used to update the data on the RSDn and RSIGn is deter-
mined by the DE bit. If the FE bit and the DE bit are not equal, the pulse
on the RSFSn is ahead.
In the Receive Clock Master mode, the RSFSn can indicate the
Basic frame, CRC Multi-frame, Signaling Multi-frame, or both the CRC
Multi-frame and Signaling Multi-frame, or the TS1 and TS 16 overhead.
All the indications are selected by the OHD bit, the SMFS bit and the
CMFS bit. The active polarity of the RSFSn is selected by the FSINV bit.
The Receive Clock Master mode includes two sub-modes: Receive
Clock Master Full E1 mode and Receive Clock Master Fractional E1
mode.
Receive Clock Master Full E1 Mode
Besides all the common functions described in the Receive Clock
Master mode, the special feature in this mode is that the RSCKn is a
standard 2.048 MHz clock, and the data in all 32 timeslots in a standard
E1 frame is clocked out by the RSCKn.
Receive Clock Master Fractional E1 Mode
Besides all the common functions described in the Receive Clock
Master mode, the special feature in this mode is that the RSCKn is a
gapped 2.048 MHz clock (no clock signal during the selected timeslot).
The RSCKn is gapped during the timeslots or the Bit 8 duration by
selecting the G56K & GAP bits in the Receive Payload Control. The data
in the corresponding gapped duration is a don't care condition.
3.17.2.2 Receive Clock Slave Mode
In the Receive Clock Slave mode, the timing signal on the RSCKn
pin and framing pulse on the RSFSn pin to output the data on the RSDn
pin are provided by the system side. When the RSLVCK bit is set to ‘0’,
each link uses its own RSCKn and RSFSn; when the RSLVCK bit is set
to ‘1’ and all four links are in the Receive Clock Slave mode, the four
links use the RSCK[1] and RSFS[1] to output the data. The signaling bits
on the RSIGn pin are per-timeslot aligned with the data on the RSDn
pin.
Table 40: Operating Modes Selection In E1 Receive Path
RMUX RMODE G56K, GAP
Operating Mode
Receive System Interface Pin
Input
Output
0
00
Receive Clock Master Full E1
X
RSCKn, RSFSn, RSDn, RSIGn
not both 0s 1 Receive Clock Master Fractional E1
1
X
Receive Clock Slave
RSCKn, RSFSn
RSDn, RSIGn
1X
X
Receive Multiplexed
MRSCK, MRSFS
MRSDA[1], MRSIGA[1] (MRSDB[1], MRSIGB[1]) 2
NOTE:
1. When the G56K, GAP bits in RPLC indirect registers are set, the PCCE bit must be set to ‘1’.
2. In Receive Multiplexed mode, two sets of multiplexed data and signaling pins (A and B) are provided. Their functions are the same. One is the backup for the other.