Would you tell me the condition(Hi/Low/Hiz/PullHigh/PullLow) of all ports of STM32G474 MCU chip when it gets boot mode with boo0 pin of high?

[TKoya.1]

I'm building a new custom PCB with the MCU(STM32G4) chip and needs to get it updated with a new Firmware through UART by main computer. then I HAVE TO CARE all MCU pins so as NOT to make bad effects on other LSI during boot mode. I need to know all the ports other than UART, I2C, USB which have potential to be communication line.

[Bob S]

Search the ST site for AN2606, "STM32 microcontroller system memory boot mode". There is a section for each (similar) CPU that describes which pins and which CPU resources the boot loader uses.

[TKoya.1]

Thank you, Bob S for your kind advice. But let me know a bit. I've read the document. that describes the resources -memory, and every communication propertis like USART, I2C, SPI and USB- the boot loader uses. What I want to know is whether the other ports except these function ports are default, as in after reset the device. I'm curious some of GPIOs that are connected with analog devices on my PCB will cause some problems during MCU FW updating.

[Tesla DeLorean]

None of this is well defined, and is subject to change. ie you can't be bound to promises you don't make.

You could do a disassembly of the ROM and get a comfort level with what it initializes and when.

Generally it is listening for signals on the pins defined in the app note, the biggest issue is usually with devices that squawk on UARTs at startup, ie GPS/GNSS receivers, etc

That said I do think the scope of what it touches is pretty limited.