CN8237EBGB Mindspeed Technologies, CN8237EBGB Datasheet - Page 107

• Manufacturer Part Number: CN8237EBGB
• Description: ATM SAR 622Mbps 3.3V ABR/CBR/GFR/UBR/VBR 456-Pin BGA
• Manufacturer: Mindspeed Technologies

Specifications of CN8237EBGB

• Package: 456BGA
• Traffic Class: ABR|CBR|GFR|UBR|VBR
• Utopia Type: Level 1|Level 2
• Host Interface: PCI
• Maximum Data Rate: 622 Mbps
• Typical Operating Supply Voltage: 3.3 V
• Minimum Operating Supply Voltage: 3.135 V

Table 4-24. Segmentation Status Queue Base Table Entry (64-bit)
Table 4-25. Segmentation Status Queue Base Table Entry (32-bit)
CN8237
ATM OC-12 ServiceSAR Plus with xBR Traffic Management
Table 4-26. Segmentation Status Queue Base Table Entry Field Descriptions
28237-DSH-001-C
Word 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Word 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
BASE_PNTR
SIZE
WRITE
READ_UD
Reserved
0
0
1
4.3.6.3 Status Queue
Field Name
63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32
SIZE
SIZE
Rsvd
Rsvd
Overflow
Points (Bits 31:3) to base of status queue. Bits 2:0 are always 0 (word-aligned).
Number of entries in this status queue:
00 = 64
01 = 256
10 = 1024
11 = 4096
SAR write pointer. Represents the SAR’s current position in the queue.
Last update of the host processor read pointer. This field is written by the host processor.
Always set to 0.
Since status queues contain a finite number of entries, it is possible that the SAR
will exhaust the available entries. Although the SAR handles this condition, the
host should attempt to prevent overflows.
(WRITE=READ_UD-1), and alerts the host to this condition by setting the OVFL
bit in the status entry. Until the host services the queue and increments the
READ_UD pointer in the base table register, the CN8237 inhibits segmentation
on all channels that report on the overflowed status queue. All other channels are
unaffected.
The CN8237 detects when it writes the last available entry in a status queue
WRITE
WRITE
Mindspeed Technologies
BASE_PNTR
BASE_PNTR
Description
Reserved
Reserved
™
4.3 Segmentation Control and Data Structures
4.0 Segmentation Coprocessor
READ_UD
READ_UD
4-27