DocID027161 Rev 1

5/26

AN4617

Hardware migration

25

1.1

Boot mode compatibility

There is no difference in boot mode configuration possibilities between F0 and L0 series but

the selection of boot mode may be slightly different.

Both series get the nBOOT1 value from an option bit located in the User option bytes. Some

more recent L0 and F0 products can do the same with the BOOT0 value optionally, too,

while BOOT0 pin can be used as GPIO in dependency on setting BOOT_SEL option bit.

Table 3 summarizes the different configurations available for selecting the Boot mode.

Embedded bootloader for both STM32F0 and STM32L0 devices uses UART and USB.

Some devices feature I2C as well, while SPI can be an additional option in the L0 series.

Table 3. Boot modes

F0/L0 boot mode configuration

Boot mode

(memory aliased in boot memory)

nBOOT1

bit

BOOT0

external pin

nBOOT0

1. The BOOT_SEL and nBOOT0 option bits are not present in all L0 and F0 products.

BOOT_SEL

bit(1)

x

0

x

1

Main Flash memory

1

1

x

1

System memory

0

1

x

1

Embedded SRAM

x

x

1

0

Main Flash memory

1

x

0

0

System memory

0

x

0

0

Embedded SRAM