ST25DV64KC datasheet(14/203 Pages) STMICROELECTRONICS

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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 write commands are legal only within a same area:

•

In RF, Write Multiple Blocks and Extended Write Multiple Blocks command are not executed and return the

error 0Fh if addresses cross an area border.

•

In I2C, a sequential write is not executed and all bytes with addresses crossing the area border are not

acknowledged if addresses cross an area border.

RF and I2C read commands are allowed over multiple areas:

•

In RF, Read Multiple Blocks and Extended read multiple Blocks (and related Fast commands) are executed

and return all readable blocks until reaching a non readable block (address read protected or non available),

even if addresses cross area borders.

•

In I2C, sequential read returns all readable bytes until reaching a non readable byte (address read protected

or non available) even if addresses cross area borders. Non readable bytes return value FFh.

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

end of the preceding area.

There are three ENDAi registers in the configuration system memory, used to define the end addresses of Area 1,

Area 2 and Area 3. The end of Area 4 is always the last block/byte of memory and is not configurable.

Figure 10. ST25DVxxKC user memory areas

Area1

(8 Blocks/32 Bytes minimum)

Area2

Area3

Area4

ST25DV user memory

ENDA1

ENDA2

ENDA3

Areas limit

registers

Block/Byte 0000h

Last Block/Byte

of user memory

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 minimum size of Area 1 is 8 blocks (32 bytes).

ST25DV04KC ST25DV16KC ST25DV64KC

User memory

DS13519 - Rev 3

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