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M29W320DB70N1E_03

32 Mbit (4Mb x8 or 2Mb x16, Boot Block) 3V Supply Flash Memory

STMicroelectronics 

M29W320DT, M29W320DB

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 address used for the commands changes de-

pending on whether the memory is in 16-bit or 8-

bit mode. See either Table 4, or 5, depending on

the configuration that is being used, for a summary

of the commands.

Read/Reset Command. The Read/Reset com-

mand returns the memory to its Read mode where

it behaves like a ROM or EPROM, unless other-

wise stated. 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.

The Read/Reset Command can be issued, be-

tween Bus Write cycles before the start of a pro-

gram or erase operation, to return the device to

read mode. Once the program or erase operation

has started the Read/Reset command is no longer

accepted. The Read/Reset command will not

abort an Erase operation when issued while in

Erase Suspend.

Auto Select Command. The Auto Select com-

mand is used to read the Manufacturer Code, the

Device Code and the Block Protection Status.

Three consecutive Bus Write operations are re-

quired to issue the Auto Select command. Once

the Auto Select command is issued the memory

remains in Auto Select mode until a Read/Reset

command is issued. Read CFI Query and Read/

Reset commands are accepted in Auto Select

mode, all other commands are ignored.

From the Auto Select mode the Manufacturer

Code can be read using a Bus Read operation

with A0 = VIL and A1 = VIL. The other address bits

may be set to either VIL or VIH. The Manufacturer

Code for STMicroelectronics is 0020h.

The Device Code can be read using a Bus Read

operation with A0 = VIH and A1 = VIL. The other

address bits may be set to either VIL or VIH. The

Device Code for the M29W320DT is 22CAh and

for the M29W320DB is 22CBh.

The Block Protection Status of each block can be

read using a Bus Read operation with A0 = VIL,

A1 = VIH, and A12-A20 specifying the address of

the block. The other address bits may be set to ei-

ther VIL or VIH. If the addressed block is protected

then 01h is output on Data Inputs/Outputs DQ0-

DQ7, otherwise 00h is output.

Read CFI Query Command. The Read CFI

Query Command is used to read data from the

Common Flash Interface (CFI) Memory Area. This

command is valid when the device is in the Read

Array mode, or when the device is in Autoselected

mode.

One Bus Write cycle is required to issue the Read

CFI Query Command. Once the command is is-

sued subsequent Bus Read operations read from

the Common Flash Interface Memory Area.

The Read/Reset command must be issued to re-

turn the device to the previous mode (the Read Ar-

ray mode or Autoselected mode). A second Read/

Reset command would be needed if the device is

to be put in the Read Array mode from Autoselect-

ed mode.

See Appendix B, Tables 21, 22, 23, 24, 25 and 26

for details on the information contained in the

Common Flash Interface (CFI) memory area.

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.

If the address falls in a protected block then the

Program command is ignored, the data remains

unchanged. The Status Register is never read and

no error condition is given.

During the program operation the memory will ig-

nore all commands. It is not possible to issue any

command to abort or pause the operation. Typical

program times are given in Table 6. Bus Read op-

erations during the program operation will output

the Status Register on the Data Inputs/Outputs.

See the section on the Status Register for more

details.

After the program operation has completed the

memory will return to the Read mode, unless an

error has occurred. When an error occurs the

memory will continue to output the Status Regis-

ter. A Read/Reset command must be issued to re-

set the error condition and return to Read mode.

Note that the Program command cannot change a

bit set at ’0’ back to ’1’. One of the Erase Com-

mands must be used to set all the bits in a block or

in the whole memory from ’0’ to ’1’.

Unlock Bypass Command. The Unlock Bypass

command is used in conjunction with the Unlock

Bypass Program command to program the memo-

ry. When the cycle time to the device is long (as

with some EPROM programmers) considerable

time saving can be made by using these com-

mands. Three Bus Write operations are required

to issue the Unlock Bypass command.

Once the Unlock Bypass command has been is-

sued the memory will only accept the Unlock By-

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