
XRT79L71
REV. P1.0.3
PRELIMINARY
1 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC
á
250
6
HEC Status into UDF2
Enable
R/W
HEC Status into UDF2 Byte Enable:
This READ/WRITE bit-field permits the user to configure the
Receive ATM Cell Processor block to insert the "HEC Byte Sta-
tus" indicator into the UDF2 byte position, within each cell that it
routes to the Receive FIFO (and then to the Receive UTOPIA
Interface).
If the user implements this configuration option, then the Receive
ATM Cell Processor block will insert some values into the UDF2
byte-field, that reflect the "HEC Byte Verification" results on this
particular "incoming" ATM cell.
0 - Configures the Receive ATM Cell Processor block to NOT
insert the "HEC Byte Status" value into the UDF2 byte of each
ATM cell that it routes to the Receive FIFO.
1 - Configures the Receive ATM Cell Processor block to insert
the "HEC Byte Status" value into the UDF2 byte of each ATM cell
that it routes to the Receive FIFO.
N
OTE
:
This bit-field is only valid if the Receive UTOPIA Interface
block has been configured to handle 56 byte cells.
5 - 4
HEC Byte Correction
Threshold[1:0]
R/W
HEC Byte Correction Threshold[1:0]:These two READ/WRITE
bit-fields permit the user to define the "HEC Byte Correction"
Threshold for the Receive ATM Cell Processor block. The "HEC
Byte Correction" threshold is defined as the minimum number of
consecutive un-erred (no HEC byte errors) cells that the Receive
ATM Cell Processor must receive before it will transition from the
"Detection Mode" into the "Correction Mode".The relationship
between the value of these bit-fields and the corresponding
"HEC Byte Correction" thresholds is tabulated below.
B
IT
N
UMBER
N
AME
T
YPE
D
ESCRIPTION
HEC Byte Status Value
Corresponding HEC Byte
Verification Results
Error Free HEC Byte Value
Uncorrectable HEC Byte Value
0x00
0xFF
Correctable HEC Byte Value
0xAA
HEC Byte Correction Threshold
1 ATM Cell with a valid HEC Byte
2 consecutive ATM Cells each
with a valid HEC Byte
4 consecutive ATM Cells each
with a valid HEC Byte
8 consecutive ATM cells, each
with a valid HEC byte
HEC Byte Correction
Threshold[1:0]
00
01
10
11