ST10F271E datasheet(37/180 Pages) STMICROELECTRONICS

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ST10F271B/ST10F271E

Internal Flash memory

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5.5

Protection strategy

The protection bits are stored in Non Volatile Flash cells inside IFLASH module, that are

read once at reset and stored in 4 Volatile registers. Before they are read from the Non

Volatile cells, all the available protections are forced active during reset.

The protections can be programmed using the Set Protection operation (see Flash Control

Registers paragraph), that can be executed from all the internal or external memories

except from the Flash itself.

Two kind of protections are available: write protections to avoid unwanted writings and

access protections to avoid piracy. In next paragraphs all different level of protections are

shown, and architecture limitations are highlighted as well.

5.5.1

Protection registers

The 4 Non Volatile Protection Registers are one time programmable for the user.

One register (FNVWPIR) is used to store the Write Protection fuses respectively for each

sector IFLASH module. The other three Registers (FNVAPR0 and FNVAPR1L/H) are used

to store the Access Protection fuses.

5.5.2

Flash non volatile write protection I register

FNVWPIR (0x08 DFB0)

NVR

Reset value: FFFFh

765

210

reserved

W0P7 W0P6W0P5W0P4W0P3W0P2 W0P1W0P0

Table 19.

Flash non volatile write protection I register

Bit

Function

W0P(9:0)

Write Protection Bank 0 / Sectors 9-0 (IFLASH)

These bits, if programmed at 0, disable any write access to the sectors of Bank 0

(IFLASH)

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