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AN4080

Boot configuration

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This flag is updated only during Option bytes loading: it is set when the content of the

address 0x08000 0000 is read as 0xFFFF FFFF, otherwise it is cleared. It means a power

on or setting of OBL_LAUNCH bit in FLASH_CR register is needed to clear this flag after

programming of a virgin device to execute user code after System reset.

Note:

If the device is programmed for a first time but the Option bytes are not reloaded, the device

will still select System memory as a boot space after a System reset. The boot loader code

is able to detect this situation and will change the boot memory mapping to Main Flash and

perform a jump to user code programmed there.

Embedded boot loader

The embedded boot loader is located in the System memory, programmed by ST during

production. It is used to reprogram the Flash memory using one of the following serial

interfaces:

•

USART on pins PA14/PA15 or PA9/PA10,

•

I2C on pins PB6/PB7 (STM32F04x and STM32F07x devices only),

•

USB DFU interface (STM32F04x, STM32F072 and STM32F078 devices only).

For further details, please refer to AN2606.