TMXF28155 Supermapper
155/51 Mbits/s SONET/SDH x28/x21 DS1/E1
Data Sheet
June 2002
532
Agere Systems Inc.
21 28-Channel Framer Block Functional Description
(continued)
21.26.4 Double NOTFAS System Time Slot (FRM_DNOTFAS) Mode
This mode is applicable to the CHI and parallel bus system interface modes (please reference
Table 359 on
page 261.)
In the default case (FRM_DNOTFAS = 0), both the FAS and NOTFAS time slots are transmitted by the
transmit system interface and expected by the receive system interface.
Setting FRM_DNOTFAS to 1 enables the NOTFAS time slot to be transmitted twice on the transmit system inter-
face in the NOTFAS and FAS time-slot (TS0) positions. Similarly, the receive system interface assumes time slot 0
will carry NOTFAS data that is repeated twice.
21.26.5 Transparent Mode
This mode is only used in the CHI mode. In the transparent DS1 mode, the transmit system interface inserts the
193rd bit of the DS1 frame in bit 7 (LSB) of the first stuffed time slot. The receive system interface takes bit 7 of the
first stuffed time slot and inserts it into the framing bit position (193rd bit on the TDM data bus).
In the transparent E1 mode, the transmit system maps 32 received time slots into the CHI time slots. Similarly, the
receive system maps the CHI time slots into the TDM bus time slots. The transmit frame formatter inserts TS0 of
the CHI (FAS/NOTFAS) into the TS0 of the frame based on the biframe alignment.
21.26.6 Loopbacks
Two forms of loopbacks are supported: single time-slot system loopback (STSSLB) and single time-slot line loop-
back (STSLLB), as shown in
Figure 69
below. When FRM_STSSLB = 1 (
Table 362
), a single time slot from the
receive system interface selected using the configuration parameter FRM_TSLBA[4:0] (
Table 362
), is looped back
to the system. The idle code, programmable using the configuration registers (FRM_IDLE[7:0] (
Table 361
)), is
transmitted to the line in place of the looped back time slot.
When FRM_STSLLB = 1 (
Table 362
), a single time slot from the transmit system interface selected using the con-
figuration parameter FRM_TSLBA[4:0], is looped back to the line. The programmable idle code is transmitted to
the system in place of the looped back time slot.
5-9030(F)r.1
Figure 69. System Loopbacks
21.26.7 System AIS
The transmit system interface transmits AIS automatically to the system on the following conditions:
I
Loss of frame alignment in the frame aligner or the mapper block (provisionable using a configuration register
bit).
I
CEPT CRC-4 multiframe alignment timer expiration (provisionable using a configuration register bit).
On-demand AIS can also be sent to the system by setting the configuration register bit for the particular link
(FRM_MANAIS (
Table 431
)).
SYSTEM
LINE
ES
SINGLE TIME SLOT SYSTEM LOOPBACK
SYSTEM
LINE
ES
SINGLE TIME SLOT LINE LOOPBACK
ES = ELASTIC STORE