M29W017D datasheet(28/36 Pages) STMICROELECTRONICS

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M29W017D

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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 is issued the de-

vice enters CFI Query mode and the data structure

is read from the memory. Tables 17, 18, 19, 20, 21

and 22 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 writ-

ten (see Table 22, 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/

Reset command to return to Read mode.

Table 17. Query Structure Overview

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

Table 18. CFI Query Identification String

Address

Sub-section Name

Description

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

40h

Primary Algorithm-specific Extended Query

table

Additional information specific to the Primary

Algorithm (optional)

61h

Security Code Area

64 bit unique device number

Address

Data

Description

Value

10h

51h

"Q"

11h

52h

Query Unique ASCII String "QRY"

"R"

12h

59h

"Y"

13h

02h

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

defining a specific algorithm

AMD

Compatible

14h

00h

15h

40h

Address for Primary Algorithm extended Query table (see Table 20)

P = 40h

16h

00h

17h

00h

Alternate Vendor Command Set and Control Interface ID Code second vendor

- specified algorithm supported

18h

00h

19h

00h

Address for Alternate Algorithm extended Query table

1Ah

00h

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