M28W640FCT_06 datasheet(58/77 Pages) STMICROELECTRONICS

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Common Flash Interface (CFI)

M28W640FCT, M28W640FCB

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Appendix B

Common Flash Interface (CFI)

The Common Flash Interface is a JEDEC approved, standardized data structure that can be

read from the Flash memory device. It allows a system software to query the device to

determine various electrical and timing parameters, density information and functions

supported by the memory. The system can interface easily with the device, enabling the

software to upgrade itself when necessary.

When the CFI Query Command (RCFI) is issued the device enters CFI Query mode and the

data structure is read from the memory. Tables 26, 27, 28, 29, 30 and 31 show the

addresses used to retrieve the data.

The CFI data structure also contains a security area where a 64 bit unique security number

is written (see Table 31: Security code area). This area can be accessed only in Read mode

by the final user. It is impossible to change the security number after it has been written by

ST. Issue a Read command to return to Read mode.

Table 26.

Query Structure Overview(1)

Query data are always presented on the lowest order data outputs.

Offset

Sub-section Name

Description

00h

Reserved

Reserved for algorithm-specific information

10h

CFI Query Identification String

Command set ID and algorithm data offset

1Bh

System Interface Information

Device timing & voltage information

27h

Device Geometry Definition

Flash device layout

Primary Algorithm-specific Extended Query

table

Additional information specific to the

Primary Algorithm (optional)

Alternate Algorithm-specific Extended

Query table

Additional information specific to the

Alternate Algorithm (optional)

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