M58LT256JST datasheet(76/106 Pages) STMICROELECTRONICS

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Common Flash Interface

M58LT256JST, M58LT256JSB

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Appendix B

Common Flash Interface

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 Read CFI Query command is issued the device enters CFI Query mode and the

data structure is read from the memory. Tables 35, 36, 37, 38, 39, 40, 41, 42, 43 and 44

show the addresses used to retrieve the data. The Query data is always presented on the

lowest order data outputs (DQ0-DQ7), the other outputs (DQ8-DQ15) are set to 0.

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

is written (see Figure 4: Protection Register memory map). 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 Array command to return to Read mode.

The Flash memory display the CFI data structure when CFI Query command is issued. In this table are

listed the main sub-sections detailed in Tables 36, 37, 38 and 39. Query data is always presented on the

lowest order data outputs.

Table 35.

Query structure overview

Offset

Sub-section name

Description

000h

Reserved

Reserved for algorithm-specific information

010h

CFI query identification string

Command set ID and algorithm data offset

01Bh

System interface information

Device timing & voltage information

027h

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)

080h

Security code area

Lock Protection Register

Unique device Number and

User Programmable OTP

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