M28W640FCB datasheet(39/55 Pages) STMICROELECTRONICS

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M28W640FCT, M28W640FCB

APPENDIX B. COMMON FLASH INTERFACE (CFI)

The Common Flash Interface is a JEDEC ap-

proved, 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 mem-

ory. The system can interface easily with the de-

vice, 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 re-

trieve the data.

The CFI data structure also contains a security

area where a 64 bit unique security number is writ-

ten (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 num-

ber after it has been written by ST. Issue a Read

command to return to Read mode.

Table 26. Query Structure Overview

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

Table 27. CFI Query Identification String

Note: Query data are always presented on the lowest order data outputs (DQ7-DQ0) only. DQ8-DQ15 are ‘0’.

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)

Offset

Data

Description

Value

00h

0020h

Manufacturer Code

01h

8848h

8849h

Device Code

Top

Bottom

02h-0Fh

reserved

Reserved

10h

0051h

"Q"

11h

0052h

Query Unique ASCII String "QRY"

"R"

12h

0059h

"Y"

13h

0003h

Primary Algorithm Command Set and Control Interface ID code 16 bit ID code

defining a specific algorithm

Intel

compatible

14h

0000h

15h

0035h

Address for Primary Algorithm extended Query table (see Table 29.)P = 35h

16h

0000h

17h

0000h

Alternate Vendor Command Set and Control Interface ID Code second vendor -

specified algorithm supported (0000h means none exists)

18h

0000h

19h

0000h

Address for Alternate Algorithm extended Query table

(0000h means none exists)

1Ah

0000h

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