LAN91C100-FD-SS SMSC [SMSC Corporation], LAN91C100-FD-SS Datasheet - Page 18

• Manufacturer Part Number: LAN91C100-FD-SS
• Description: FEAST Fast Ethernet Controller with Full Duplex Capability
• Manufacturer: SMSC [SMSC Corporation]

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
Destination 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:
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.
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
requirements 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 - 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.
A special BANK (BANK7) exists to support the addition of external registers.
SMSC DS – LAN91C100FD REV. B
BYTE
BYTE
HIGH
LOW
OFFSET
C
A
E
0
2
4
6
8
ED 00 00 00 00 00
0D 00 00 00 00 00
2F 00 00 00 00 00
01 00 00 00 00 00
RESERVED (0)
BANK SELECT
bit 15
EPH STATUS
bit 7
X
X
COUNTER
ADDRESS
BANK0
MCR
RCR
TCR
MIR
bit 14
bit 6
X
X
Table 2 - Internal I/O Space Mapping
NAME
BANK SELECT
bit 13
bit 5
CONTROL
GENERAL
BANK1
CONFIG
X
X
HASH VALUE 5-0
BASE
IA0-1
IA2-3
IA4-5
000 000
010 000
100 111
111 111
Page 18
bit 12
bit 4
X
X
MMU COMMAND
BANK SELECT
FIFO PORTS
bit 11
INTERRUPT
bit 3
BANK2
POINTER
TYPE
X
X
DATA
DATA
PNR
MULTICAST TABLE BIT
bit 10
bit 2
MT-0 bit 0
MT-2 bit 0
MT-4 bit 7
MT-7 bit 7
X
X
BANK SELECT
REVISION
BANK3
MGMT
bit 9
bit 1
MT0-1
MT2-3
MT4-5
MT6-7
ERCV
X
X
SYMBOL
bit 8
bit 0
X
X
Rev. 01-20-06