LAN91C100 Datasheet, PDF (68/101 Pages) SMSC Corporation – FEAST™ Fast Ethernet Controller

BOARD SETUP INFORMATION
The following parameters are obtained from the
EEPROM as board setup information:
ETHERNET INDIVIDUAL ADDRESS
I/O BASE ADDRESS
10BASE-T or AUI INTERFACE
MII or ENDEC INTERFACE
INTERRUPT LINE SELECTION
All the above mentioned values are read from
the EEPROM upon hardware reset. Except for
the INDIVIDUAL ADDRESS, the value of the
IOS switches determines the offset within the
EEPROM for these parameters, in such a way
that many identical boards can be plugged into
the same system by just changing the IOS
jumpers.
In order to support a software utility based
installation, even if the EEPROM was never
programmed, the EEPROM can be written using
the LAN91C100. One of the IOS combination is
associated with a fixed default value for the key
parameters (I/O BASE, INTERRUPT) that can
always be used regardless of the EEPROM
based value being programmed. This value will
be used if all IOS pins are left open or pulled
high.
The EEPROM is arranged as a 64 x 16 array.
The specific target device is the 9346 1024-bit
Serial EEPROM. All EEPROM accesses are
done in words. All EEPROM addresses in the
spec are specified as word addresses.
REGISTER
Configuration
Register
EEPROM WORD
ADDRESS
IOS Value * 4
Base Register _{(IOS Value * 4) + 1}
INDIVIDUAL ADDRESS
20-22 hex
If IOS2-0 = 7 , only the INDIVIDUAL ADDRESS
is read from the EEPROM. Currently assigned
values are assumed for the other registers.
These values are default if the EEPROM read
operation follows hardware reset.
The EEPROM SELECT bit is used to determine
the type of EEPROM operation: a) normal or b)
general purpose register.
a) NORMAL EEPROM OPERATION -
EEPROM SELECT bit = 0
On EEPROM read operations (after reset or
after setting RELOAD high) the
CONFIGURATION REGISTER and BASE
REGISTER are updated with the EEPROM
values at locations defined by the IOS2-0 pins.
The INDIVIDUAL ADDRESS registers are
updated with the values stored in the
INDIVIDUAL ADDRESS area of the EEPROM.
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