The role of BOOT0 and BOOT1 in STM32 problem set

1. Function and purpose

        There are two pins BOOT0 and BOOT1 on each STM32 chip. The level status of these two pins when the chip is reset determines which area the program starts from after the chip is reset.

BOOT1=x BOOT0=0 // Boot from user flash memory, this is the normal working mode.

BOOT1=0 BOOT0=1 // Boot from system memory. The program function started in this mode is set by the manufacturer.

BOOT1=1 BOOT0=1 // Boot from built-in SRAM. This mode can be used for debugging.

2. Usage

Normally, the BOOT0 and BOOT1 jumpers are both set to 0 (ground). However, in the case of ISP download, BOOT0=1, BOOT1=0. After the download is complete, the BOOT0 jumper is set back to 0, that is, BOOT0=0, BOOT1=0.

3. Notes

Generally, the built-in SRAM is not used for booting (BOOT1=1BOOT0=1), because the data in the SRAM will be lost after the power is off. In most cases, SRAM is only used for debugging, and it can also be used for other purposes. For example, to do local fault diagnosis, write a small program to load it into the SRAM to diagnose other circuits on the board, or use this method to read and write the Flash or EEPROM on the board. This method can also be used to remove the read and write protection of the internal Flash. Of course, when the read and write protection is removed, the content of the Flash is automatically cleared to prevent malicious software from copying.