M58PR256LE datasheet(42/119 Pages) STMICROELECTRONICS

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Program operations

M58PR256LE, M58PR512LE, M58PR001LE

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5.2

Program modes

There are two program modes, which allow the Flash memory to store different types of

data: control program mode and object program mode.

5.2.1

Control program mode

The control program mode is best suited to the storage of small, dynamic information.

Typically such data is contained within one program region and it is frequently updated

and/or new data is added to it.

Program regions are configured in the control program mode by programming data only to

the ’A’ halves (bit A3= 0) of the segments they contain. The ’B’ halves of the segments must

remain erased, meaning that they should not contain any zeros (see Figure 5: Program

regions configured in control or object program mode).

In a program region of 1 Kbyte configured in the control program mode, only 512 bytes of

data can be stored.

When the program regions are configured in the control program mode, any program

method can be used: the single word or the buffered program methods.

Once a program region has been configured in the control program mode, if a zero is written

to a ’B’ half of one of its segments, the program operation is terminated and an error is

generated. The Status Register bits SR4 and SR9 are set to ‘1’. (Refer to Status Register

and to Table 13: Relationships between program methods and program modes for details.)

The program mode of a program region configured in the control program mode can only be

changed by first erasing the block that contains the program region.

5.2.2

Object program mode

The object program mode is best suited to the storage of large amounts of static

information. In a program region of 1 Kbyte configured in the object program mode, 1 Kbyte

of data can be stored.

When a program region is configured in the object program mode, it cannot be re-

programmed or have new data added without first erasing the entire block that contains the

program region.

Program regions are configured in the object program mode simply by programming at least

one bit in the ’B’ half (A3 = 1) of one of the segments they contain.

If the programmed data is smaller than 1 Kbyte, the unused space remains in the erased

state (all the bits set to FFFFh), but can no longer be used to program data. See Figure 5:

Program regions configured in control or object program mode.

When the program regions are configured in the object program mode, only the buffered

program methods can be used. If an attempt is made to use the single word program

method, the program operation is aborted and Status Register Error bits SR4 and SR8 are

set to ‘1’. (Refer to Status Register and to Table 13: Relationships between program

methods and program modes, for details.)

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