LAN91C111 Datasheet, PDF (40/125 Pages) SMSC Corporation – 10/100 Non-PCI Ethernet Single Chip MAC + PHY

LAN91C111
HASH VALUE - Provides the hash value used to index the Multicast Registers. Can be used by receive routines to speed
up the group address search. The hash value consists of the six most significant bits of the CRC calculated on the Des-
tination Address, and maps into the 64 bit multicast table. Bits 5,4,3 of the hash value select a byte of the multicast table,
while bits 2,1,0 determine the bit within the byte selected. Examples of the address mapping:
Address
ED 00 00 00 00 00
0D 00 00 00 00 00
01 00 00 00 00 00
2F 00 00 00 00 00
Hash Value 5-0
000 000
010 000
100 111
111 111
Multicast Table Bit
MT-0 bit 0
MT-2 bit 0
MT-4 bit 7
MT-7 bit 7
MULTCAST - Receive frame was multicast. If hash value corresponds to a multicast table bit that is set, and the address
was a multicast, the packet will pass address filtering regardless of other filtering criteria.
8.3 I/O Space
The base I/O space is determined by the IOS0-IOS2 inputs and the EEPROM contents. To limit the I/O space require-
ments to 16 locations, the registers are assigned to different banks. The last word of the I/O area is shared by all banks
and can be used to change the bank in use. Registers are described using the following convention:
OFFSET
NAME
TYPE
SYMBOL
HIGH
bit 15
bit 14
bit 13
bit 12
bit 11
bit 10
bit 9
bit 8
BYTE
X
X
X
X
X
X
X
X
LOW
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
BYTE
X
X
X
X
X
X
X
X
FFSET - Defines the address offset within the IOBASE where the register can be accessed at, provided the bank select
has the appropriate value.
The offset specifies the address of the even byte (bits 0-7) or the address of the complete word.
The odd byte can be accessed using address (offset + 1).
Some registers (like the Interrupt Ack., or like Interrupt Mask) are functionally described as two eight bit registers, in that
case the offset of each one is independently specified.
Regardless of the functional description, all registers can be accessed as doublewords, words or bytes.
The default bit values upon hard reset are highlighted below each register.
DS00002276A-page 40
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