M29W008ET datasheet(13/43 Pages) STMICROELECTRONICS

13 / 43 page

M29W008ET, M29W008EB

3 Bus Operations

13/43

3.2

Special bus operations

Additional bus operations can be performed to read the Electronic Signature and also to apply

and remove Block Protection. These bus operations are intended for use by programming

equipment and are not usually used in applications. They require VID to be applied to some

pins.

3.2.1

Read Electronic Signature

The memory has two codes, the Manufacturer code and the Device code, that can be read to

identify the memory.

These codes allow programming equipment or applications to automatically match their

interface to the characteristics of the M29W008E.

The electronic Signature is output either by applying the signals listed in

Table 2: Bus

Operations or by issuing an Auto Select command (see Section 4.2: Auto Select command).

3.2.2

Block Protection and Unprotection

Each block can be individually protected against accidental Program or Erase using

programming equipment. Protected blocks can be unprotected to allow data to be changed.

There are two methods available for protecting and unprotecting the blocks, one for use on

programming equipment (Programmer Technique) and the other for in-system use (In-System

Technique). Block Protect and Chip Unprotect operations are described in

Appendix B: Block

protection.

Table 2.

Bus Operations

Operation

Address Inputs A0-A19

DQ0-

DQ7

Byte Read

VIL

VIH

Cell Address

Data

Output

Byte Write

VIL

VIH

VIL

VIH

Command Address

Data

Input

Output Disable

VIL

VIH

XHi-Z

Standby

VIH X(1)

X = VIL or VIH.

X(1)

VIH

XHi-Z

Read

Electronic

signature

Manufacturer Code

VIL

VIH

A0= VIL, A1= VIL, A9=VID,

others address bits are ‘Don’t Care’

20h

Device

Code

M29W008ET

VIL

VIH

A0= VIH, A1= VIL, A9=VID,

others address bits are ‘Don’t Care’

D2h

M29W008EB

DCh

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