AN2606 datasheet(14/155 Pages) STMICROELECTRONICS

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General bootloader description

AN2606

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DocID13801 Rev 21

General bootloader description

3.1

Bootloader activation

The bootloader is activated by applying one of these patterns:

Table 2. Bootloader activation patterns

Note:

The bootloader activation procedure is not the same for all STM32 products. In each STM32

product bootloader section we specify which pattern is used to execute bootloader.

In addition to patterns described above, user might execute Bootloader by performing a

jump to system memory from user code (refer to table 64 for system memory address).

Before jumping to Bootloader user must:

•

Disable all peripheral clocks

•

Disable used PLL

•

Disable interrupts

•

Clear pending interrupts

System memory boot mode can be exited by getting out from bootloader activation

condition and generating hardware reset or using Go command to execute user code.

Note:

For some products with dual bank mechanism, the jump to Bootloader might result in

jumping again to user code (and thus Bootloader communication protocol is not executed).

Please refer to product's "Dual Bank Boot Implementation" flowchart for more details.

i.e. In order to jump and execute Bootloader communication protocol, you might configure

SYSCFG register by software to map System Memory on address 0x00000000 prior to

jumping, when this feature is available.

Patterns

Condition

Pattern1

Boot0(Pin) = 1 and Boot1(Pin) = 0

Pattern2

Boot0(Pin) = 1 and nBoot1(bit) = 1

Pattern3

Boot0 (Pin)= 1, Boot1(Pin) = 0 and BFB2 (bit) = 1

Boot0(Pin) = 0, BFB2 (bit) = 0 and both banks don’t contain valid code

Boot0(Pin) = 1, Boot1(Pin) = 0, BFB2 (bit) = 0 and both banks don’t contain

valid code

Pattern4

Boot0 (Pin)= 1, Boot1(Pin) = 0 and BFB2 (bit) = 1

Boot0(Pin) = 0, BFB2 (bit) = 0 and both banks don’t contain valid code

Boot0(Pin) = 1, Boot1(Pin) = 0 and BFB2 (bit) = 0

Pattern5

Boot0 (Pin)= 1, Boot1(Pin) = 0 and BFB2 (bit) = 0

Boot0(Pin) = 0, BFB2 (bit) = 1 and both banks don’t contain valid code

Boot0(Pin) = 1, Boot1(Pin) = 0 and BFB2 (bit) = 1

Pattern6

Boot0(Pin) = 1, nBoot1(bit) = 1 and nBoot0_SW(bit) = 1

nBoot0(bit) = 0, nBoot1(bit) = 1 and nBoot0_SW(bit) = 0

Boot0(Pin) = 0, nBoot0_SW(bit) = 1 and main flash empty

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