STM8AP5X76TAY datasheet(14/100 Pages) STMICROELECTRONICS

14 / 100 page

Product overview

STM8AF61xx, STM8AF51xx

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5.4.2

Write protection (WP)

Write protection in application mode is intended to avoid unintentional overwriting of the

memory in case of user software malfunction. Code update in user mode is still possible

after execution of a specific MASS key sequence.

The program memory is divided into two areas:

●

Main program memory: Up to 128 Kbytes minus user-specific boot code (UBC)

●

UBC: Configurable up to 128 Kbytes

The UBC area also remains write-protected during in-application programming. It permits

storage of the boot program or specific code libraries.

The boot area is a part of the program memory that contains the reset and interrupt vectors,

the reset routine and usually the IAP and communication routines. The UBC area has a

second level of protection to prevent unintentional erasing or modification during IAP

programming. This means that the MASS keys do not unlock the UBC area.

The size of the UBC is programmable through the UBC option byte, in increments of 512

bytes, by programming the UBC option byte in ICP mode.

Figure 2.

STM8A products: Flash memory organization

Programmable area from 1 Kbyte

Data

UBC area

Program memory area

Data memory area (2 Kbytes)

(first two pages) up to program memory

EEPROM

Remains write protected during IAP

memory

Write access possible for IAP

Option bytes

end - maximum 128 Kbytes

Flash

program

memory

STM8AP5X76TAY Datasheet(PDF) 14 Page - STMicroelectronics