cx28365 Mindspeed Technologies, cx28365 Datasheet - Page 48

• Manufacturer Part Number: cx28365
• Description: X12, X6, X4 T3/e3 Framer And Atm Cell Transmission Convergence Sublayer Processor
• Manufacturer: Mindspeed Technologies

Functional Description
2-10
DS3 Mode
There are 56 frame Overhead bits in a DS3 M-frame structure. See
details.
The External-Data source option for the DS3 mode provides the ability to insert all
frame Opportunity bits with the data stream. When the framer operates in C-bit parity
mode, there is an option to either insert all the frame Opportunity bits with the data
stream or none of them by setting bit ExtDat in the Transmit Overhead Insertion 1
Control register. When the framer operates in M13/M23 mode there are five options
concerning the insertion of Opportunity bits with the data stream:
Table 2-2. Overhead Choice
When the Frame Overhead bits are not chosen to be inserted via the data stream, the
following source options are provided: internally generated, taken from register, or
entered through an external pin. For enabling sourcing options, the Frame Overhead
bits are divided into groups where each group of overheads has its own sourcing
options. Some groups and their source options are different for C-bit parity and M13/
M23 mode of operation. The difference is in the C-bits, which are divided into more
groups in C-bit parity mode.
C-Bit Parity and M13/M23 Modes of Operation
The following groups of overheads have the same options for both operational modes.
1.
2.
3.
4.
5.
Preliminary Information/Mindspeed Proprietary and Confidential
Framing bits (F-bits and M-bits)—When the External-Data method is disabled, the
three M-bits and the 28 F-bits can be either generated internally by the framer
(when ExtFrmAl bit is 0) or inserted through TEXTI pin (when ExtFrmAl bit is 1).
All Opportunity bits can be inserted with the data stream by setting ExtDat bit to 1.
Only C-bits (Justification Control bits) enter with the data stream and the 7 Stuff
Opportunity bits are inserted via TEXTI by setting bit ExtDat to 0, ExtFEBE/Cj-
bit to 0, and ExtStf to 1.
Only 7 Stuff Opportunity bits are inserted with the data stream while justification
control bits are inserted from TEXTI by setting bit ExtDat to 0, ExtFEBE/Cj-bit
to 1, and ExtStf to 0.
Both C-bits (Justification Control bits) and the 7 Stuff Opportunity bits are
inserted with the data stream by setting bit ExtDat to 0, ExtFEBE/Cj-bit to 0, and
ExtStf to 0.
None of the Opportunity bits are inserted with data (Justification Control and
Stuff Opportunity bits enter through external pin, and other overload bits are
internally generated) by setting ExtDat to 0, and ExtFEBE/Cj-bit to 1 and ExtStf
to 1.
Operation
1
2
3
4
5
Mindspeed Technologies™
ExtDat
1
0
0
0
0
Setting of External Data
ExtFEBE/Cj
0
0
1
0
1
CX28365/6/4 Data Sheet
Appendix
ExtStf
0
1
0
0
1
B, for
500028C