M29W320DB datasheet(16/56 Pages) STMICROELECTRONICS

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Bus operations

M29W320DT, M29W320DB

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3.6

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.

3.6.1

Electronic Signature

The memory has two codes, the manufacturer code and the device code, that can be read

to identify the memory. These codes can be read by applying the signals listed in Table 2

and Table 3, Bus Operations.

3.6.2

Block Protect and Chip Unprotect

Each block can be separately protected against accidental Program or Erase. The whole

chip can be unprotected to allow the data inside the blocks to be changed.

Block Protect and Chip Unprotect operations are described in Appendix C: Block Protection.

Table 2.

Bus Operations, BYTE = VIL

(1)

Operation

Address Inputs

DQ15A–1, A0-A20

Data Inputs/Outputs

DQ14-DQ8

DQ7-DQ0

Bus Read

VIL

VIH

Cell Address

Hi-Z

Data Output

Bus Write

VIL

VIH

VIL

Command Address

Hi-Z

Data Input

Output Disable

VIH

Hi-Z

Standby

VIH

Hi-Z

Read Manufacturer

Code

VIL

VIH

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

Others VIL or VIH

Hi-Z

20h

Read Device Code

VIL

VIH

A0 = VIH, A1 = VIL,

A9 = VID, Others VIL or VIH

Hi-Z

CAh (M29W320DT)

CBh (M29W320DB)

X = VIL or VIH.

Table 3.

Bus Operations, BYTE = VIH

(1)

Operation

Address Inputs

A0-A20

Data Inputs/Outputs

DQ15A–1, DQ14-DQ0

Bus Read

VIL

VIH

Cell Address

Data Output

Bus Write

VIL

VIH

VIL

Command Address

Data Input

Output Disable

VIH

XHi-Z

Standby

VIH

Hi-Z

Read Manufacturer

Code

VIL

VIH

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

Others VIL or VIH

0020h

Read Device Code

VIL

VIH

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

Others VIL or VIH

22CAh (M29W320DT)

22CBh (M29W320DB)

X = VIL or VIH.

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