XRT7245
DS3 UNI FOR ATM
á
PRELIMINARY
REV. 1.03
106
3.3.2.95
Rx CP User Cell Filter Mask Header—Byte 4
This “Read/Write” register allows the user to specify
which bit(s), in octet 4 of the incoming user cell (in
the Receive Cell Processor) are to be checked against
the corresponding bit(s) in the “Rx CP User Cell Filter
Pattern Header—Byte 4” register (Address = 5Bh) by
the User Cell Filter, when determining whether a given
user cell is to be filtered out or written to the Rx FIFO.
Writing a “1” to a particular bit in this register, forces
the User Cell Filter to check and compare the corre-
sponding bit in octet 4 of the incoming user cell with
the corresponding bit in the “Rx CP User Cell Filter
Pattern Header—Byte 4” register.
Writing a “0” to a particular bit, causes the User Cell
Filter to treat the corresponding bit of octet 4 in the
incoming user cell as a “don’t care” (e.g., to forgo the
comparison between the corresponding bit in octet 4
of the incoming user with the corresponding bit in the
“Rx CP User Cell Filter Pattern Header—Byte 4”
register.)
For more information on User Cell Filtering, please
see Section 7.3.2.3.2.
3.3.2.96
Tx CP Control Register
The Transmit Cell Processor Control Register allows
the user to control many aspect of the operation of the
Transmit Control Processor. The description of each
bit follows.
Bit 7—Scrambler Enable
This “Read/Write” bit-field allows the user to enable or
disable the Cell Scrambler, within the Transmit Cell
Processor. When the Cell Scrambler is enabled, it will
“scramble” the payload portion of each cell prior to its
transmittal to the Transmit PLCP Processor (or the
Transmit DS3 Framer). When the Cell Scrambler is
disabled, then the Transmit Cell Processor will not
scramble the payload portion of each cell. Instead,
the Transmit Cell Processor will transmit cells to the
Transmit PLCP Processor (or the Transmit DS3
Framer), with the cell payload data as received from
the Tx FIFO.
Writing a “0” to this bit-field disables the Cell Scrambler.
Writing a “1” enables the Cell Scrambler.
For more information on the Cell Scrambler, please
see Section 6.2.2.2.
Bit 6—Coset Enable
This “Read/Write” bit-field allows the user to enable or
disable the modulo-2 addition of the Coset polynomial,
x
6
+ x
4
+ x
2
+ 1 to a newly computed HEC byte. Once
this polynomial has been added to the existing HEC
byte, this new modification to the contents of the
HEC byte will now be referred to as the “HEC byte”.
Writing a “0” to this bit-field disables this addition.
Writing a “1” to this bit-field enables this addition.
For more information into the function/purpose of the
Coset polynomial, please see Section 6.2.2.1.3.
Bit 5—HEC Byte Insert Enable—Assigned Cells
This “Read/Write” bit-field allows the user to enable
or disable the calculation and insertion of the HEC
byte into user or assigned cells.
Writing a “0” into this bit-field disables the Transmit
Cell Processor from calculating and inserting the
HEC byte into each outgoing user or assigned cell.
Writing a “1” into this bit-field enables this feature.
Address = 5Fh, Rx CP User Cell Filter Mask Header—Byte 4
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Rx User Cell Mask Header—Byte 4
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
1
1
1
1
1
1
1
1
Address = 60h, Tx CP Control Register
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Rx User Cell Mask Header—Byte 4
R/W
R/W
R/W
R/W
R/W
R/W
R/W
RUR
1
1
1
1
0
0
1
0