M29F800DT datasheet(42/53 Pages) STMICROELECTRONICS

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Common Flash Interface (CFI)

M29F800DT

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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 is issued the device enters CFI Query mode and the data

structure is read from the memory. Table 21, Table 22, Table 23, Table 24, Table 25, and

Table 26 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 26: 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 21.

Query structure overview(1)

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

Address

Sub-section name

Description

x16

10h

20h

CFI Query Identification String Command set ID and algorithm data offset

1Bh

36h

System Interface Information

Device timing & voltage information

27h

4Eh

Device Geometry Definition

Flash device layout

40h

80h

Primary Algorithm-specific

Extended Query table

Additional information specific to the

Primary Algorithm (optional)

61h

C2h

Security Code Area

64 bit unique device number

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