ST25DV04K datasheet(27/220 Pages) STMICROELECTRONICS

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ST25DV04K ST25DV16K ST25DV64K

Memory management

219

4.2.1

User memory areas

The user memory can be split into different areas, each one with a distinct access privilege.

RF and I2C read and write commands are legal only within a same zone:

•

In RF, a multiple read or a multiple write command is not executed and returns the error

code 0Fh if addresses cross the area borders.

•

In I2C, a read data always return FFh after crossing an area border. A write command

is not acknowledged and not executed if the command crosses the area border.

Each user memory area is defined by its ending block address ENDAi. The starting block

address is defined by the end of the preceding area.

There are three ENDAi registers in the configuration system memory, used to define the end

block addresses of Area 1, Area 2 and Area 3. The end of Area 4 is always the last block of

memory and is not configurable.

Figure 8. ST25DVxxx user memory areas

On factory delivery all ENDAi are set to maximum value, only Area1 exists and includes the

full user memory.

A granularity of 8 Blocks (32 Bytes) is offered to code area ending points.

An area’s end limit is coded as followed in ENDAi registers:

•

Last RF block address of area = 8 x ENDAi + 7 => ENDAi = int(Last Areai RF block

address / 8)

•

Last I2C byte address of area = 32 * ENDAi + 31 => ENDAi = int(Last Areai I2C byte

address / 32)

•

As a consequence, ENDA1 = 0 means size of Area 1 is 8 blocks (32 Bytes).

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