
XRT7245
DS3 UNI FOR ATM
á
PRELIMINARY
REV. 1.03
98
3.3.2.77
Rx CP Additional Configuration Register
Bit 5—User Cell Filter Discard
This “Read/Write” bit-field allows the user to specify
which cells are to be discarded by the User Cell Filter.
Writing a “0” to this bit-field causes the User Cell Fil-
ter to discard all user cells NOT matching the header
byte patterns, defined in the “Rx CP User Cell Filter
Pattern Header byte” registers and the “Rx CP User
Cell Filter Mask Header byte” registers.
Writing a “1” to this bit-field causes the User Cell Filter
to discard all users cells MATCHING the header byte
patterns, defined in the “Rx CP User Filter Cell Pattern
Header byte” registers and the “Rx CP User Cell Filter
Mask Header byte” registers.
For more information on the User Cell Filter, please
see Section 7.3.2.3.2.
Bit 4—User Cell Filter Enable
This “Read/Write” bit-field allows the user to enable or
disable the User (or Assigned) Cell Filter. If the User
Cell Filter is disabled then all non-Idle Cells will be
written the Rx FIFO, within the Receive UTOPIA
Interface block. However, if the User Cell Filter is
enabled, then only those user cells, specified by the
following parameters; will be written into the Rx FIFO.
The contents of bit-field number 5, within this
Register (User Cell Filter Discard).
The contents of the four “Rx CP User Cell Filter
Pattern Header Byte” registers (Address = 58h
through 5Bh), and
The contents of the four “Rx CP User Cell Filter
Mask Header Byte” registers (Address = 5Ch
through 5Fh)
Writing a “0” to this bit-field disables the User Cell Filter.
Writing a “1” enables the User Cell Filter.
For more information on the User Cell Filter, please
see Section 7.3.2.3.2.
Bits 3 and 2—Correction Threshold[1, 0]
These two “Read/Write” bit-fields allow the user to
define the Correction Threshold, “M”, as specified
below. For more information on Correction Thresh-
olds, please see Section 7.3.2.2.
Correction Threshold[1, 0] = 0, 0, then M = 0
The Receive Cell Processor, while performing HEC
Verification, will always operate in the “Correction”
mode.
Correction Threshold[1, 0] = 0, 1, then M = 1
The Receive Cell Processor, while performing HEC
Verification, must detect a single error-free cell be-
fore it will transition from the “Detection” mode to the
“Correction” mode.
Correction Threshold[1, 0] = 1, 0, then M = 3
The Receive Cell Processor, while performing HEC
Verification, must detect 3 consecutive error-free
cells before it will transition from the “Detection”
mode to the “Correction” mode.
Correction Threshold[1, 0] = 1, 1, then M = 7
The Receive Cell Processor, while performing HEC
Verification, must detect 7 consecutive error-free
cells before it will transition from the “Detection”
mode to the “Correction” mode.
Bit 1—Correction Enable
This “Read/Write” bit-field allows the user to enable
or disable the “Correction” Mode, within the HEC
Byte Verification Algorithm. Specifically, if the user
disables the “Correction” mode, then the Receive
Cell Processor, while performing HEC byte verifica-
tion, will only operate in the “Detection” Mode (e.g.,
cells with single-bit errors are NOT corrected, and
are subject to discard).
Writing a “0” to this bit-field disables the “Correction”
mode. Writing a “1” to this bit-field enables the
“Correction” Mode.
Address = 4Dh, Rx CP Additional Configuration 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
Unused
User Cell Filter
Discard
User Cell Filter
Enable
Corr Thresh [1]
Corr Thresh [0]
Corr Enable
Unused
RO
RO
R/W
R/W
R/W
R/W
R/W
RO
0
0
0
0
1
1
1
0