STM32F030 and BOOT0 pin

Question

I'm trying to create circuit with STM32F030K6T6 microcontroler and im not sure about one thing.

There is only BOOT0 pin (without BOOT1) and maybe I'm blind but I can't find description about this pin in ST documentation (I was looking in "DoclD024849 Rev 1" document which is datasheet for mentioned uC).

One thing I found is a description about pair of BOOT pins, showed below (based on "DoclD018940 Rev 5" - RM0091 Reference Manual document):

BOOT0=0 BOOT1=x - main flash memory boot
BOOT0=1 BOOT1=0 - system memory boot (boot loader)
BOOT0=1 BOOT1=1 - RAM memory

What I want to do is to program chip by SWD and I'm not realy sure what I need to do with BOOT0 pin.

The questions are: Should I pull-up this pin? What is the default value of BOOT1 in this case?

Answer 1

In STM32F030 datasheet you can find that BOOT0 is the microcontroller pin, and BOOT1 is boot selector option bit (page 12)

In RM0360 on page 62 you can find that bit in FLASH_OBR register. There is also section about how to setup Boot configuration.

In the STM32F0x0, three different boot modes can be selected through the BOOT0 pin and boot configuration bits nBOOT1 in the User option byte, as shown in the following table.

(...)

The boot mode configuration is latched on the 4th rising edge of SYSCLK after a reset. It is up to the user to set boot mode configuration related to the required boot mode. The boot mode configuration is also re-sampled when exiting from Standby mode.

Answer 2

The simple answer: SWD doesn't need to be connected during boot so boot pin configuration doesn't matter for that (unless you want to prevent execution of some "hazardous" SW). If you're intending to write your SW to main flash I would just suggest leaving BOOT0 down to save the trouble.

If the case would have been that you want to flash the chip using serial (UART1), you'd need to invoke the bootloader (BOOT0=1 BOOT1=0) for that.