TMXF28155/51 Super Mapper
155/51 Mbits/s SONET/SDH x28/x21 DS1/E1
Preliminary Data Sheet
May 2001
388
Agere Systems Inc.
17 TMUX Functional Description
(continued)
The second section after the switch, the transport overhead section, is broken down into the following functional
parts:
I
TOAC insert
I
Sync status byte (S1) insert
I
M0/M1
—
REI-L Insert
I
K1 and K2 insert
I
AIS-L insert
I
B2 calculation and insert
I
F1 byte insert
I
B1 generate and error insert
I
Scrambler
I
J0 insert control
I
A2 error insert
All insert control functions that are inhibited will insert all zeros or all ones, depending on the value of microproces-
sor register bit, SMPR_OH_DEFLT (
Table 67 on pag e68
).
17.6.3 POAC Insert
One path overhead access channel (POAC) is provided on-chip to provision the path overhead (POH) portion of
the outgoing frame. The TMUX transmits up to three STS-1s. The register bits TMUX_TPOAC_SEL[1:0] (
Table 118
on page115
) designate which STS-1s POH is inserted from the transmit POAC channel.
TMUX_TPOAC_SEL[1:0] = 00 designates no TMUX_TPOAC insertion, TMUX_TPOAC_SEL[1:0] = 01 designates
STS-1 #1, TMUX_TPOAC_SEL[1:0] = 10 designates STS-1 #2, and TMUX_TPOAC_SEL[1:0] = 11 designates
STS-1 #3.
A POAC channel consists of the following signals:
I
A 576 kHz inverted clock signal sourced by the TMUX (TPOACCLK, pin AE4).
I
A 576 kbits/s serial data signal received by the TMUX in the transmit direction (TPOACDATA, pin AD5).
An 8 kHz synchronization signal (TPOACSYNC, pin AC5), sourced by the TMUX. The sync signal is normally low.
During the last clock period of each frame, coincident with the least significant bit of the eighth byte, the sync signal
is high.
The data signal is partitioned into frames of 9 bytes. The frame repetition rate is 8 kHz. Each byte consists of 8 bits
that are transmitted/received most significant bit first. The MSB of the first byte of each frame contains an odd/even
parity bit over the 72 bits of the previous frame. The remaining 7 bits of this byte are not specified. The B3, G1, and
H4 transmit path overhead bytes are not provisionable via the POAC channel.
Bytes shown in
Table 530
summarize the access capabilities of the transmit POAC channel. X indicates a don
’
t
care.
Table 530. Path Overhead Byte Access
—
Transmit Direction
J1
X
F2
X
F3
K3
N1
POH Parity
C2