reset stm32f412 fail

[aacqu]

Hi friends . I have a new board developed with STM32F412Z 144 pins, I have a problem with Nreset of microcontroller . I tried to mount a simple reset circuit so as suggest by ST. a simple capacitors with pullup 4K7 and push button reset that close to zero nreset input .

First problem is that stm32 after power up never going in activity ( I programmed a very simple code that blink some leds every second) ; if we push a reset button some times processor start in execution, but sometimes he doesn't start at all . Because is a very simple section I realy don't understund what happen. Boot0 pin is pull-downed with 10K and boot1 pin is pull upped with 10K too . Because we using j.link for debugging , when stm32 don't start He doesn't work in debug , so I really don't know what can we doing for move on form this situtation. any suggest for try to resolve ?

[Tesla DeLorean]

Make sure the VDDA supply is present.

Check supply voltages.

Check voltages on VCAP pins. Check cap values.

Check the level on the NRST pin.

Use a POR circuit that thesholds the supply, say 2.7V, and hold NRST low for 100-200mS

Have someone review the schematic.

[Alex R]

It it possible that the code is entering one of the Exception Handlers (which by default many compilers just put an infinite loop) and it appears that it is not working.

You might want use the J-Link and try to debug using single-step, so that you can slowly see where the code might fail. You may need to configure your project to stop at main() after programming, so that is doesn't start running right after programming.

It could be that it using a memory location that is not defined on this processor, or some stack overflow, corrupting internal variables.

[aacqu]

Thanks for answer . some feedback at your suggest .

We laredy use J-link under atollic suite tools and when we start with debugger processor doesn't ansewer ( my be that it's in boot mode or similar )

VDDA is connect together with Vdd 3,3V and is OK present ( remember some time processor start correctly and work so 3,3V is ok )

Level Nrst is a first step that I done 3,3V using a 4.K7 pull

I normally use a POR ADM811 but because this is a POR wiith totem pole output I removed it and used simple cap + resistor , Today I will try to use ADM809 that is same of ASDM811 but with open collector outuput

Any way Nucelo board doesn't have a POR and working fine

[S.Ma]

Could it be that on your board there are other components using a different supply which goes up before the MCU and in this case the MCU GPIOs are receiving voltages before the MCU does? (kind of latchup of MCU powered not by its supply but its IOs)?

Grounding issue? Sometime the problem is so obvious that we keep looking at details missing the elephant in the hallway 😉