problem with NVIC_SystemReset

[fabricepeden]

Posted on March 24, 2017 at 14:47

Hi everybody,

I'm using a STM32F205VE on one of my electronic board.

I'd like to reset my microcontroller, so I use the function NVIC_SystemReset that I can find in core_cm3.h but it never works.

My board is not resetting so I don't understand what happen and why my board is not resetting.

If you've have some ideas, I'll be very happy.

Regards,

Fabrice Péden

[waclawek.jan]

Posted on March 24, 2017 at 14:55

How is NRST wired on your board?

JW

[fabricepeden]

Posted on March 24, 2017 at 15:13

Thank you for your quick reply.

My reset pin is wired on the reset pin of my programmation connector with a 10k pull-up resistor.

I've also tried without this pull-up resistor, the result still be the same.

Fabrice

[fabricepeden]

Posted on March 24, 2017 at 15:51

Find below, the pin state when I execute NVIC_SystemReset()

The reset pin is tied to 0V during 33µs.

[Tesla DeLorean]

Posted on March 24, 2017 at 15:29

Make sure you have nothing driving it high (push-pull) externally.

Review the pin state with a scope when you use NVIC_SystemReset()

[fabricepeden]

Posted on March 24, 2017 at 16:38

I have put some breakpoints in NVIC_SystemReset().

__DSB();  => OK, firmware is going here

SCB->AIRCR = ((0x5FA << SCB_AIRCR_VECTKEY_Pos) | (SCB->AIRCR & SCB_AIRCR_PRIGROUP_Msk) | SCB_AIRCR_SYSRESETREQ_Msk); 

 => OK, firmware is going here

__DSB(); 

 => NOK, firmware is never going here

while(1);

The problem comes from the update of the register. However, the update of this register seems to be good as describes in the cortex documentation.

Regards,

Fabrice

[Tesla DeLorean]

Posted on March 24, 2017 at 16:20

And the CPU doesn't go into the ResetHandler? You're checking/verifying this how?

Does it continue to execute code on the other side of NVIC_SystemReset()?

[fabricepeden]

Posted on March 27, 2017 at 11:52

Hi everybody,

I've tried to put 'NVIC_SystemReset();' somewhere else in my code, and it's always the same, my µc doesn't reset, it seems to be freeze (I have a LCD screen, I can see that this one is frozen).

Is something can block (IT...) this function ?

Regards,

Fabrice

[Adalgiso]

Posted on March 27, 2017 at 12:10

in the main add this before doing anything else, I am not sure how long the delay needs to be but for me this works

/* delay absolutely necessary when a narrow reset pulse on the NRST or/and with software or watchdog reset */

/* Little delay */ for(i=0;i<512;i++) { __NOP(); }

[fabricepeden]

Posted on March 27, 2017 at 14:23

Thank you for your suggestion, but it doesn't work.

I've tried to put (my watchdog is activated):

while(1)

{

   __NOP();

}

But it's the same, I think the core is stopped (I use also an external watchdog so I can see some LEDs and buzzer whic are activated) but my µc doesn't restart.

Regards,

Fabrice