STM8S datasheet(43/467 Pages) STMICROELECTRONICS

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Flash program memory and data EEPROM

Figure 11. UBC area size definition on high density STM8S and

STM8AF with up to 128 Kbytes of Flash program memory

1. UBC[7:0] = 0x00 means no user boot code area is defined. Refer to the datasheets for the description of

the UBC option byte.

2. The first 2 pages (1 Kbytes) contain the interrupt vectors, of which only 128 bytes (32 IT vectors) are used.

4.4.4

Data EEPROM (DATA)

The data EEPROM area can be used to store application data. By default, the DATA area is

write protected to prevent unintentional modification when the main program is updated in

IAP mode. The write protection can be unlocked only by using a specific MASS key

sequence (refer to Enabling write access to the DATA area).

Refer to Section 4.4: Memory organization for the size of the DATA area.

4.4.5

Main program area

The main program is the part of the Flash program memory which is used to store the

application code (see Figure 6, Figure 7 and Figure 8).

4.4.6

Option bytes

The option bytes are used to configure device hardware features and memory protection.

They are located in a dedicated memory array of one block.

The option bytes can be modified both in ICP/SWIM and in IAP mode, with OPT bit of the

FLASH_CR2 register set to 1 and the NOPT bit of the FLASH_NCR2 register set to 0 (see

Section 4.8.2: Flash control register 2 (FLASH_CR2) and Section 4.8.3: Flash

complementary control register 2 (FLASH_NCR2)).

STM8S Datasheet(PDF) 43 Page - STMicroelectronics