M39432 datasheet(13/28 Pages) STMICROELECTRONICS

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M39432

Table 9. Flash Sector Protection

Note: 1. X = Don’t Care

2. SA = Sector address

A12

A16

A17

A18

DQ0 - DQ7

VIL

VIH

VID

VIL

VID

Protection Activation

VIL

VIH

VIL

VIH

VIL

VIH

VIL

VID

XSA

Verify Sector Protection Status:

when DQ0=1, the sector is

protected

Table 10. Flash Unprotection (all sectors)

Note: 1. X = Don’t Care

2. SA = Sector address

A12

A16

A17

A18

DQ0 - DQ7

VID

VIH

VID

VIL

VID

VIH

Activation of Unprotected mode

VIL

VIH

VIL

VIH

VIL

VIH

VID

XSA

Verify Sector Protection Status:

when 00h, the sector is

unprotected

be addressed to a whole sector. Either one sector

(or more) can be explicitly selected for erasure, or

the Bulk Erase instruction can be used to erase all

the sectors in the Flash memory block.

During an Erase cycle, the memory status may be

checked by reading the status bits DQ7, DQ6 and

DQ5, as described on page 8. The Error bit (DQ5)

returns a ’1’ if there has been an Erase Failure (if

the maximum number of Erase cycles has been

exceeded).

The Program instruction to a byte in the Flash

memory block is ignored if it is in a protected

sector. Similarly, the Bulk Erase instruction is

ignored if all the Flash memory sectors are

protected.

If all the addressed sectors, for an Erase

instruction, are protected, nothing is erased. DQ7

and DQ6 are set to ’0’ for about 100

µs, and then

are returned to their values from the previously

addressed byte.

Bulk

Erase

Instruction.

The

Bulk

Erase

instruction uses six Write operations followed by a

number of Read operations, to read the status

part of the Bulk Erase instruction sequence is

wrong, the device reverts to being in its Read

mode for the Flash memory, and does not execute

the erase instruction.

The M39432 rejects any further instructions that

arrive during the execution of the Bulk Erase

instruction.

Sector Erase Instruction. The Sector Erase

instruction uses six Write operations to specify the

first sector that is to be erased, and an additional

Write operation for each additional sector that is to

be erased in parallel with the first. This is

summarized in Table 4. These Write operations

are transmitted under normal Page Write timing

conditions.

The status of the internal timer can be monitored

on DQ3 (Erase Time-Out bit) as described on

page 10. If DQ3 is ’0’ the Sector Erase instruction

has been received and the timer is counting. If

DQ3 is ’1’, the time-out has expired, and the

M39432 is either in the process of erasing, or has

finished (as indicated on DQ7 and DQ6).

Any instruction arriving before the expiration of the

Erase Time-Out period, other than Erase Suspend

or Erase Resume instruction, aborts the Erase

instruction, and resets the device in its read Flash

memory mode.

During the execution of the Erase instruction, the

Flash memory block accepts only Reset and

Erase Suspend instructions.

Erase Suspend Instruction. When a Sector

Erase cycle is in progress, the Erase Suspend

instruction can be used to suspend the cycle. This

allows the reading of data from another Flash

sector while the Sector Erase instruction is on

hold.

This instruction involves writing B0h at any

address (as shown in Table 4). Erase Suspend is

accepted only during the Sector Erase instruction

execution, and defaults to the Read Flash memory

mode, otherwise. An Erase Suspend instruction

executed during an Erase Time-Out will, in

addition to suspending the Erase, terminate the

time-out period.

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