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M29W512B

Table 4. Commands

Note: X Don’t Care, PA Program Address, PD Program Data.

All values in the table are in hexadecimal.

The Command Interface only uses address bits A0-A10 to verify the commands, the upper address bits are Don’t Care.

Read/Reset. After a Read/Reset command, read the memory as normal until another command is issued.

Auto Select. After an Auto Select command, read Manufacturer ID or Device ID.

Program, Unlock Bypass Program, Chip Erase. After these commands read the Status Register until the Program/Erase Controller com-

pletes and the memory returns to Read Mode.

Unlock Bypass. After the Unlock Bypass command issue Unlock Bypass Program or Unlock Bypass Reset commands.

Unlock Bypass Reset. After the Unlock Bypass Reset command read the memory as normal until another command is issued.

Command

Bus Write Operations

1st

2nd

3rd

4th

5th

6th

Addr

Data

Addr

Data

Addr

Data

Addr

Data

Addr

Data

Addr

Data

Read/Reset

1X

F0

3

555

AA

2AA

55

X

F0

Auto Select

3

555

AA

2AA

55

555

90

Program

4

555

AA

2AA

55

555

A0

PA

PD

Unlock Bypass

3

555

AA

2AA

55

555

20

Unlock Bypass

Program

2X

A0

PA

PD

Unlock Bypass Reset

2

X

90

X

00

Chip Erase

6

555

AA

2AA

55

555

80

555

AA

2AA

55

555

10

COMMAND INTERFACE

All Bus Write operations to the memory are inter-

preted by the Command Interface. Commands

consist of one or more sequential Bus Write oper-

ations. Failure to observe a valid sequence of Bus

Write operations will result in the memory return-

ing to Read mode. The long command sequences

are imposed to maximize data security.

The commands are summarized in Table 4, Com-

mands. Refer to Table 4 in conjunction with the

text descriptions below.

Read/Reset Command. The Read/Reset com-

mand returns the memory to its Read mode where

it behaves like a ROM or EPROM. It also resets

the errors in the Status Register. Either one or

three Bus Write operations can be used to issue

the Read/Reset command.

If the Read/Reset command is issued during a

Chip Erase operation the memory will take about

10µs to abort the Chip Erase. During the abort pe-

riod no valid data can be read from the memory.

Issuing a Read/Reset command during a Chip

Erase operation will leave invalid data in the mem-

ory.

Auto Select Command. The Auto Select com-

mand is used to read the Manufacturer Code and

the Device Code. Three consecutive Bus Write op-

erations are required to issue the Auto Select com-

mand. Once the Auto Select command is issued

the memory remains in Auto Select mode until an-

other command is issued.

From the Auto Select mode the Manufacturer

Code can be read using a Bus Read operation

Code for STMicroelectronics is 20h.

The Device Code can be read using a Bus Read

Device Code for the M29W512B is 27h.

Program Command. The

Program

command

can be used to program a value to one address in

the memory array at a time. The command re-

quires four Bus Write operations, the final write op-

eration latches the address and data in the internal

state machine and starts the Program/Erase Con-

troller.