M50LPW012 データシートの表示（PDF） - STMicroelectronics

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M50LPW012

2 Mbit (256Kb x8, Boot Block) 3V Supply Low Pin Count Flash Memory

STMicroelectronics 

M50LPW012

Table 9. A/A Mux Bus Operations

Operation

G

Bus Read

VIL

Bus Write

VIH

Output Disable

VIH

Reset

VIL or VIH

W

VIH

VIL

VIH

VIL or VIH

Table 10. Manufacturer and Device Codes

Operation

G

W

Manufacturer Code

VIL

VIH

Device Code

VIL

VIH

RP

VPP

DQ7-DQ0

VIH

Don’t Care

Data Output

VIH

Float or VCC or VPPH

Data Input

VIH

Don’t Care

Hi-Z

VIL

Don’t Care

Hi-Z

RP

A18-A1

A0

DQ7-DQ0

VIH

VIL

VIL

20h

VIH

VIL

VIH

3Bh

COMMAND INTERFACE

All Bus Write operations to the memory are

interpreted by the Command Interface.

Commands consist of one or more sequential Bus

Write operations.

After power-up or a Reset operation the memory

enters Read mode.

The commands are summarized in Table 12,

Commands. Refer to Table 12 in conjunction with

the text descriptions below.

Read Memory Array Command. The Read Mem-

ory Array command returns the memory 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

memory to Read mode. Once the command is is-

sued the memory remains in Read mode until an-

other command is issued. From Read mode Bus

Read operations will access the memory array.

While the Program/Erase Controller is executing a

Program or Erase operation the memory will not

accept the Read Memory Array command until the

operation completes.

Read Status Register Command. The Read Sta-

tus Register command is used to read the Status

Register. One Bus Write cycle is required to issue

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

Register for details on the definitions of the Status

Register bits.

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

command is issued subsequent Bus Read

operations read the Manufacturer Code or the

Device Code until another command is issued.

After the Read Electronic Signature Command is

issued the Manufacturer Code and Device Code

can be read using Bus Read operations using the

addresses in Table 11.

Program Command. The Program command

can be used to program a value to one address in

the memory array at a time. Two Bus Write

operations are required to issue the command; the

second Bus Write cycle latches the address and

data in the internal state machine and starts the

Program/Erase Controller. Once the command is

issued subsequent Bus Read operations read the

Status Register. See the section on the Status

Register for details on the definitions of the Status

Register bits.

If the address falls in a protected block then the

Program operation will abort, the data in the

memory array will not be changed and the Status

Register will output the error.

During the Program operation the memory will

only accept the Read Status Register command

and the Program/Erase Suspend command. All

other commands will be ignored. Typical Program

times are given in Table 13.

Note that the Program command cannot change a

bit set at ‘0’ back to ‘1’ and attempting to do so will

not cause any modification on its value. One of the

Erase commands must be used to set all of the

bits in the block to ‘1’.

See Figure 13, Program Flowchart and Pseudo

Code, for a suggested flowchart on using the

Program command.

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