Standalone application doesn't run unless NRST is forced to 0V

[Hicham Chaabane]

Posted on April 30, 2018 at 13:32

Hi guys,

I'm using the  

STM32L475RCT

 in a custom board. When using the JLink everything is working fine but when I discounnect the Jlink and power cycle the board the application doesn't work at all. Each time I have to force NRST to 0 and release it in ordre to make the application works.

I have 100nF capacitor between the NRST pin and GND as recommended in ST  datasheet(

6.3.15

).

I checked the voltage on the NRST pin and it seems correct : it goes from 0.358V to 3.1V  in ~4ms at board power up which follow the required low level voltage ( VIL(NRST)  =0.3?VDDIOx = 0.984V) and high level reset voltage  ( VIH(NRST) = 0.7?VDDIOx = 2.29V).

Any thoughts on where the problem might be ?

#stpm32-reset #reset #stm32l4 #nrst #reset-problem

[Hicham Chaabane · Accepted solution]

Posted on May 02, 2018 at 13:06

Guys, I figured out.

I connected the BOOT0 to GND and the standalone application started working without the JLINK.

Not sure the reason of this since in the manual leaving BOOT0 NC won't have an effect on the startup sequence ! I think I'll need to do more reading on this subject.

Thank you for the help

[Tesla DeLorean]

Posted on May 02, 2018 at 13:18

BOOT0 effects if it runs code from FLASH or ROM, if you leave it floating on slow rising supplies it tends to look high and doesn't run your code in FLASH