CRD8900A-1 Cirrus Logic Inc, CRD8900A-1 Datasheet - Page 89

• Manufacturer Part Number: CRD8900A-1
• Description: KIT EVAL FOR CS8900A
• Manufacturer: Cirrus Logic Inc
• Series: CrystalLAN™r

Specifications of CRD8900A-1

• Main Purpose: Interface, Ethernet
• Utilized Ic / Part: CS8900A
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Other names: 598-1163

DS271F5
5.2.13 Broadcast Frame Hashing Excep-
tion
Table 26 describes in detail the content of the
RxEvent register for each output of the hash
and address filters, and describes an excep-
tion to normal processing. That exception can
occur when the hash-filter Broadcast address
matches a bit in the Logical Address Filter. To
properly account for this exception, the soft-
ware driver should use the following test to de-
Notes: 6. Broadcast frames are accepted as Multicast frames if and only if all the following conditions are met
CS8900A
Crystal LAN™ Ethernet Controller
Received
Individual
Address
Multicast
Address
Address
Type of
Frame
7. NOT (Note 1).
Frame?
simultaneously:
a) the Logical Address Filter is programmed as: (MSB) 0000 8000 0000 0000h (LSB). Note that this
LAF value corresponds to a Multicast Addresses of both all 1s and 03-00-00-00-00-01.
b) the Rx Control Register (register 5) is programmed to accept IndividualA, MulticastA, RxOK-only,
and the following address filters were enabled: IAHashA and BroadcastA.
Erred
yes
yes
no
no
no
no
Hashed
bit
to
don’t care ExtraData Runt CRC Error Broadcast Individual Adr
don’t care ExtraData Runt CRC Error Broadcast Individual Adr
Passes
Filter?
Hash
yes
yes
no
no
OR gate
64-input
Destination Address (DA)
from incoming frame
Table 26. Contents of RxEvent Upon Various Conditions
ExtraData Runt CRC Error Broadcast Individual Adr
ExtraData Runt CRC Error Broadcast Individual Adr
1
CIRRUS LOGIC PRODUCT DATASHEET
Figure 23. Hash Filter Operation
Hash Table Index
Hash table index
Written into PacketPage base + 150h
64-bit Logical Address Filter (LAF)
CS8900A
Bits F-A
Logic
CRC
6-to-64 decoder
termine if the RxEvent register contains a
normal RxEvent (meaning bits E-A are used
for Extra data, Runt, CRC Error, Broadcast
and IndividualAdr) or a hash-table RxEvent
(meaning bits F-A contain the Hash Table In-
dex).
If bit Hashed =0, or bit RxOK=0, or (bits F-A =
02h and the destination address is all ones)
then RxEvent contains a normal RxEvent, else
RxEvent contained a hash RxEvent.
Contents of RxEvent
(MSB)
6-bit Hash Register (HR)
32-bit CRC value
[Hash Table Index]
Hashed
Bit 9
1
0
0
1
0
0
(LSB)
64
RxOK
Bit 8
1
1
0
1
1
0
IAHash
Bit 6
1
0
0
0
0
0
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