BOOT0/BOOT1 pins - boot mode doubt

[jeferson]

Posted on May 09, 2016 at 13:14

Hello all.

I have a little doubt about BOOT0/BOOT1 pins, they select the boot mode.

After reading about in some pages, I understood that ''System memory boot'' selects the builtin bootloader to write a new firmware using a PC's serial port or USB.

That's not my intention for the current project (STM32F401RCT6 part), because the application firmware update will be done through one USART by using a GSM modem. In current schematic, BOOT0 is connected directly to GND and BOOT1 is floating. Are these connections (BOOT0/1) correct for my intention? 

Regards in advance.

#boot1 #boot0 #bootloader

[Walid FTITI_O]

Posted on May 09, 2016 at 13:46

Hi pehls.jeferson.001,

STM32 enter system memory boot mode if the boot pins as follow:

(Boot0 = 1, Boot1= 0)

You find all the necessary information in the application note ''STM32 System Memory Boot Mode''

https://my.st.com/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/Attachments/18225/AN26pdf

-Hannibal-

[jeferson]

Posted on May 09, 2016 at 14:22

Hannibal, I understood that, but ''system memory boot'' is selected only when the builtin bootloader is to be used. I want to use a bootloader through a GSM modem. This way, I think I did the correct in schematic, by connecting BOOT0 to GND and BOOT1 is floating.

I did the question just to confirm that I did correct. 

Regards.

[Tesla DeLorean]

Posted on May 09, 2016 at 15:04

The parts come unprogrammed, consider also the cost/efficacy of your production programming and testing.

I'd pull pull down resistors on both, and provide test points. Just grounding the pins tends to result on PCB layout that is hard to overcome when you need too. Provide access to USART1/USART3

[jeferson]

Posted on May 09, 2016 at 15:12

clive1, thanks.

I'll put to both pins a PD resistor, 1K is ok? what do you think?

Regards.

[Tesla DeLorean]

Posted on May 09, 2016 at 17:13

I'd lean to at least 10K, but 47K would also be fine.