EEPROM Interface

5.7Parallel FLASH Memory

All Ethernet controllers except the 82540EP/EM provide an external parallel interface to an optional FLASH or boot EEPROM device. Accesses to the FLASH memory are controlled by the Ethernet controllers, but are accessible to host software as normal PCI reads or writes to the FLASH memory mapping range. Software developers can also map FLASH memory to I/O space. The Ethernet controllers support 8-bit wide parallel FLASH memory up to 4 Mb (512 KB); an appropriate size for typical applications would be 1 Mb (128 KB). The size of the FLASH implemented in the design can be encoded into bits in the EEPROM. FLASH and expansion ROM base address registers are reconfigured based on these EEPROM settings.

Representative FLASH memory devices that have been found to work satisfactorily with the Ethernet controllers are listed in Table 5-21:

Table 5-21. FLASH Memory Manufacturers

Manufacturer

Manufacturer’s Part

Number

 

 

 

Atmel

AT49LV010

AT49BV002AN-70J1

 

 

 

Silicon Storage

SST39V512

39VF020-90-4I-NH

Technology

39VF020-70-4C-NH

 

 

 

The FLASH memory interface trace routing is not critical because the interface runs at a very slow speed. In a tightly space-constrained design, the FLASH memory device is a good choice for placement in relative isolation from the Ethernet controllers.

Note: The 82540EP/EM provides an external interface to a serial FLASH or Boot EEPROM device. See Appendix B for more information.

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Intel Intel Gigabit Ethernet Controllers, PCI-X manual Parallel Flash Memory, Flash Memory Manufacturers, Number