Wrong clock frequency after IWDG reset [STM32F405]

[luigi23]

Posted on April 09, 2016 at 12:42

Hi all,

I'm experiencing a strange problem on STM32F405

When a IWDG reset happens, the uC restarts with a wrong clock frequency, I think it's running from HSI instead of HSE.  Same problem happens even if I call NVIC_SystemReset()

If I power the board or I reset the board using the reset pin everything is working fine.

Should I reconfigure something, or it should be a clock startup problem?

I'm using this 8MHz xtal (

http://www.abracon.com/Resonators/abls.pdf

) with 22pf load capacitance, and uC frequency should be 168MHz.

Any help is really appreciated.

Luigi

#stm32f405-startup-watchdog-clock

[Tesla DeLorean]

Posted on April 09, 2016 at 15:08

The part ALWAYS starts from the HSI. You have code called in SystemInit() that turns on the HSE and the PLL, perhaps your code there is failing, or the crystal isn't starting. Suggest you review the, what paths that is taking, and what is happening externally.

There are app notes on the correct part selection.