
Agere Systems Inc.
49
Data Sheet
May 2001
155/622/2488 Mbits/s Data Interface
TDAT042G5 SONET/SDH
Overview
(continued)
Over-Fiber Mode
Over-fiber mode is used for packet delivery over fiber. No SONET overhead is added in this mode. Since no
SONET overhead is added, the OHP and PT blocks must be configured for the bypass mode.
In transmitting from the TDAT042G5 to the line, the data engine maps the data payload into a full SONET frame
starting at what normally would be the first A1 byte. The data engine continues to map payload into the full SONET
frame until an end of packet or end of frame is reached, at which time the data engine halts the mapping of the
incoming data stream into the SONET frame until the next start of frame.
When TDAT042G5 is receiving from the line, the data engine must be provisioned to receive the maximum packet
size, unless the location of the last byte of the packet is known in advance. If the size of the packet is not known,
one must program the data engine to receive the entire SONET frame. The external UTOPIA interface device must
then be capable of extracting the variable length packets from the full SONET frame.
Details of the over-fiber mode are given in the Data Engine (DE) Block section, page 82.
Test and General-Purpose I/O Support
The device is provisioned, controlled, and monitored using a generic 16-bit microprocessor interface. A standard
five-signal
IEEE
-1149.1 compliant JTAG test port is also provided for boundary-scan purposes.
A 4-bit GPIO (general-purpose input/output) interface is provided to control and/or monitor other onboard devices.
External Interfaces
Figure 4 shows the external interfaces.
5-6745(F).br.3
Figure 4. External Interface Summary Diagram
MPU AND TEST INTERFACE
TxD
ECLREF
2
RxD
RxCLK
4 x 24 Rx UTOPIA
+5 MPHY ADDRESS
4 x 24 Tx UTOPIA
+5 MPHY ADDRESS
U
OHP
4
GPIO
T
X
LINE
R
X
LINE
TxFSYNC
TxCK
TxCKQ
CLKDIV
5
JTAG
RST
ICT
PMRST
MPMODE
MPCLK
CS
INT
16
DATA
ADDR
ADS
R/W
DS
16
DT
T
X
TOHF
4
T
X
TOHD
T
X
TOHCK
R
X
REF
R
X
TOHF
R
X
TOHCK
4
R
X
TOHD
4
348 SIGNAL PINS
4
2
2
2
32
32
2