M50FLW040A datasheet(18/52 Pages) STMICROELECTRONICS

18 / 52 page

M50FLW040A, M50FLW040B

18/52

COMMAND INTERFACE

All Bus Write operations to the device are inter-

preted by the Command Interface. Commands

consist of one or more sequential Bus Write oper-

ations. An internal Program/Erase Controller han-

dles all timings, and verifies the correct execution

of the Program and Erase commands. The Pro-

gram/Erase Controller provides a Status Register

whose output may be read at any time to monitor

the progress or the result of the operation.

The Command Interface reverts to the Read mode

when power is first applied, or when exiting from

Reset. Command sequences must be followed ex-

actly. Any invalid combination of commands will be

ignored. See Table 11. for the available Command

Codes.

Table 11. Command Codes

The following commands are the basic commands

used to read from, write to, and configure the de-

vice. The following text descriptions should be

read in conjunction with Table 13..

Read Memory Array Command. The

Read

Memory Array command returns the device to its

Read mode, where it behaves like a ROM or

EPROM. One Bus Write cycle is required to issue

the Read Memory Array command and return the

device to Read mode. Once the command is is-

sued, the device remains in Read mode until an-

other command is issued. From Read mode, Bus

Read operations access the memory array.

If the Program/Erase Controller is executing a Pro-

gram or Erase operation, the device will not accept

any Read Memory Array commands until the oper-

ation has completed.

For a multibyte read, in the FWH mode, the ad-

dress, that was transmitted with the command, will

be automatically aligned, according to the MSIZE

granularity. For example, if MSIZE=7, regardless

of any values that are provided for A6-A0, the first

output will be from the location for which A6-A0 are

all ‘0’s.

Read Status Register Command. The

Read

Status Register command is used to read the Sta-

tus Register. One Bus Write cycle is required to is-

sue the Read Status Register command. Once the

command is issued, subsequent Bus Read opera-

tions read the Status Register until another com-

mand is issued. See the section on the Status

Read Electronic Signature Command. The

Read Electronic Signature command is used to

read the Manufacturer Code and the Device Code.

One Bus Write cycle is required to issue the Read

Electronic Signature command. Once the com-

mand is issued, the Manufacturer Code and De-

vice Code can be read using conventional Bus

Read operations, and the addresses shown in Ta-

ble 12..

Table 12. Electronic Signature Codes

Note: 1. A22 should be ‘1’, and the ID lines and upper address bits

should be set according to the rules illustrated in Table 5.,

Table 6. and Table 8..

The device remains in this mode until another

command is issued. That is, subsequent Bus

Read operations continue to read the Manufactur-

er Code, or the Device Code, and not the Memory

Array.

Program Command. The

Program

command

can be used to program a value to one address in

the memory array at a time.

The Program command works by changing appro-

priate bits from ‘1’ to ‘0’. (It cannot change a bit

from ‘0’ back to ‘1’. Attempting to do so will not

modify the value of the bit. Only the Erase com-

mand can set bits back to ‘1’. and does so for all of

the bits in the block.)

Two Bus Write operations are required to issue the

Program command. The second Bus Write cycle

latches the address and data, and starts the Pro-

gram/Erase Controller.

Hexa-

decimal

Command

10h

Alternative Program Setup, Double/

Quadruple Byte Program Setup, Chip

Erase Confirm

20h

Block Erase Setup

32h

Sector Erase Setup

40h

Program, Double/Quadruple Byte

Program Setup

50h

Clear Status Register

70h

Read Status Register

80h

Chip Erase Setup

90h

Read Electronic Signature

B0h

Program/Erase Suspend

D0h

Program/Erase Resume, Block Erase

Confirm, Sector Erase Confirm

FFh

Read Memory Array

Code

Address1

Data

Manufacturer Code

...00000h

20h

Device Code

M50FLW040A

M50FLW040B

...00001h

08h

28h

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