21
Agere Systems Inc.
Data Sheet
June 2002
TMXF28155 Supermapper
155/51 Mbits/s SONET/SDH x28/x21 DS1/E1
3 Pin Information
(continued)
Table 5. Telecom Bus (Low-Speed I/O) Pin Description
(continued)
3.3.4 TOAC and POAC
The transport and path overhead access channels (TOAC and POAC) allow parts of the SONET/SDH overhead to
be examined externally (receive direction) or overwritten (transmit direction) through serial data ports. Each port
has clock and data lines and a synchronization signal that marks the last bit of the frame so that the rest of the
overhead bytes can be identified.
The receive TOAC and POAC channels contain all of the respective overheads bytes. The transmit channels con-
tain space for all the overhead bytes, but whether they are actually transmitted depends on how the device is pro-
grammed. Some overhead bytes cannot be modified; some may be modified only through the CPU port; some may
be modified only through the overhead access channels; and some may be modified either through the CPU port,
or through the overhead access channels.
Pin
AC3
Symbol
TLSC52
Type
—
I/O
I/O
Description
Transmit Low-Speed Clock.
When in output (master) mode,
it is the transmit side 51.84 MHz clock output synchronous to
transmit high-speed input clock. When in input mode, it
receives a 51.84 MHz clock input synchronous to transmit
high-speed input clock
Note:
TLSCLK is used as the master clock for the T1/E1
framer and should therefore is provided even if the
TMUX SPE and VT mappers are not used.
Transmit Low-Speed Sync.
When in output (master) mode,
it is the transmit side frame sync output synchronous to
51.84 MHz output. When in input (slave) mode, it receives
the transmit side frame sync input synchronous to 51.84 MHz
input.
AD2
TLSSYNC52
—
I/O
Table 6. TOAC and POAC
Pin
AD1
Symbol
RTOACCLK
Type
—
I/O
O
Description
Receive TOAC Clock.
Receive side serial access channel
clock output for the transport overhead bytes.
Receive TOAC Data.
Receive side serial access channel
data output for the transport overhead bytes.
Receive TOAC Synchronization.
Receive side sync output
for TOAC channel. Active-high during the LSB of the last
byte.
Transmit TOAC Clock.
Transmit side serial access channel
clock output for the transport overhead bytes.
Transmit TOAC Data.
Transmit side serial access channel
data input for the transport overhead bytes.
AD3
RTOACDATA
—
O
AA5
RTOACSYNC
—
O
AB6
TTOACCLK
—
O
AE2
TTOACDATA
—
I
Pull-down
O
AF3
TTOACSYNC
—
Transmit TOAC Synchronization.
Transmit side sync out-
put for TOAC channel. Active-high during the LSB of the last
byte.