ST72260G datasheet(16/171 Pages) STMICROELECTRONICS

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ST72260G, ST72262G, ST72264G

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FLASH PROGRAM MEMORY (Cont’d)

4.5 Memory Protection

There are two different types of memory protec-

tion: Read Out Protection and Write/Erase Protec-

tion which can be applied individually.

4.5.1 Read out Protection

Read out protection, when selected, makes it im-

possible to extract the memory content from the

microcontroller, thus preventing piracy.

In flash devices, this protection is removed by re-

programming the option. In this case the program

memory is automatically erased and the device

can be reprogrammed.

Read-out protection selection depends on the de-

vice type:

– In Flash devices it is enabled and removed

through the FMP_R bit in the option byte.

– In ROM devices it is enabled by mask option

specified in the Option List.

4.5.2 Flash Write/Erase Protection

Write/erase protection, when set, makes it impos-

sible to both overwrite and erase program memo-

ry. Its purpose is to provide advanced security to

applications and prevent any change being made

to the memory content.

Warning: Once set, Write/erase protection can

never be removed. A write-protected flash device

is no longer reprogrammable.

Write/erase protection is enabled through the

FMP_W bit in the option byte.

4.6 Register Description

FLASH CONTROL/STATUS REGISTER (FCSR)

Read /Write

Reset Value: 000 0000 (00h)

1st RASS Key: 0101 0110 (56h)

2nd RASS Key: 1010 1110 (AEh)

Note: This register is reserved for programming

using ICP, IAP or other programming methods. It

controls the XFlash programming and erasing op-

erations. For details on XFlash programming, refer

to the ST7 Flash Programming Reference Manual.

When an EPB or another programming tool is

used (in socket or ICP mode), the RASS keys are

sent automatically.

000

OPT

LAT

PGM

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