STM32F031 low voltage reset - bootloader boot0 pin

[Gregory Holcomb]

Posted on September 09, 2017 at 00:02

I have two micros communicating over SPI bus, one is a STM32F031 running application code.  I can interrogate the STM32F031 for its firmware version and if it is not the correct version I power off its 3.3 volts, raise the boot0 pin and power it back up into bootloader and transfer the correct version firmware using UART from one micro to the other over UART.  

For testing purposes I need to know about low voltage reset.  What voltage I must drop 3.3 volts to and for how long in order to guarantee a check of check of boot0 and entrance into the bootloader.  Are these volts/timings specified, or what would be reasonable?

[Tesla DeLorean]

Posted on September 09, 2017 at 01:54

Couldn't you just clamp NRST easier?

[Gregory Holcomb]

Posted on September 11, 2017 at 16:34

There is a flex circuit involved with a limited number of conductors connecting the micros so we would prefer to avoid having to connect NRST even though it is the preferred way to generate a reset.

[Vangelis Fortounas]

Posted on September 11, 2017 at 16:51

Hi!

this is from  STM32f031

http://www.st.com/content/ccc/resource/technical/document/datasheet/4d/c2/7e/10/77/4f/4a/60/DM00104043.pdf/files/DM00104043.pdf/jcr:content/translations/en.DM00104043.pdf

Rgrds

vf