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Software Developer’s Manual 229
Register Descriptions
This register provides software direct access to the EEPROM. Software can control the EEPROM
by successive writes to this register. Data & address information is clocked into the EEPROM by
software toggling the EESK bit (2) of this register with EECS set to 1b. Data output from the
EEPROM is latched into bit 3 of this register via the internal 62.5 MHz clock and can be accessed
by software via reads of this register.
Note: Attempts to write to the FLASH device when writes are disabled (FEW = 01b) should not be
attempted. Behavior after such an operation is undefined, and can result in component and/or
system hangs.
EE_REQ 6
1
0b
Request EEPROM Access
The software must write a 1b to this bit to get direct EEPROM
access. It has access when EE_GNT is 1b. When the software
completes the access it must write a 0b.
EE_GNT 7
1
0b
Grant EEPROM Access
When this bit is 1b the software can access the EEPROM using the
SK, CS, DI, and DO bits.
EE_PRES 8
1
1b
0b
2
EEPROM Present
This bit indicates that an EEPROM is present by monitoring the
EEDO input for a active-low acknowledge by the serial EEPROM
during initial EEPROM scan. 1b = EEPROM present.
EE_SIZE 9
1
0b
EEPROM Size
0b = 1024-bit (64 word) NM93C46 compatible EEPROM
1b = 4096-bit (256 word) NM93C66 compatible EEPROM
This bit indicates the EEPROM size, based on acknowledges seen
during EEPROM scans of different addresses. This bit is read-only.
Note: This is a reserved bit for the 82541xx and 82547GI/EI.
EE_SIZE 10
1
0b
EEPROM Size (82541xx and 82547GI/EI)
For Microwire EEPROMs:
0b = 6-bit addressable (64 words).
1b = 8-bit addressable (256 words).
For SPI EEPROMs:
0b = 8-bit addressable.
1b = 16-bit addressable.
Reserved 12:11 00b
Reserved
Should be written with 0b to ensure future compatibility. Reads as
0b.
EE_TYPE 13
1
1b
EEPROM Type: Reflects the EE_MODE pin. (82541xx and
82547GI/EI)
0b = Microwire.
1b = SPI.
Reserved 31:14 0b
Reserved
Should be written with 0b to ensure future compatibility. Reads as
0b.
1. Not applicable to the 82544GC/EI.
2. 82541xx and 82547GI/EI only.
Field Bit
Initial
Value
Description