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STM32F103 watchdog problem

David.Fabian
Associate II
Posted on February 24, 2016 at 16:02

Hello together,

I have some problems with the IWDG of the STM32F103RBT6. I hope you can help me.

The initialization:

  // Clear reset flags

  if( RCC_CSR & (1 << 29))

  {

    RCC_CSR |= (1<<24);

  }

    

  /* Configure the watchdog */

  IWDG_KR  = 0x5555; /* Configuration access enabled */

  IWDG_PR  = 0x0002; /* Prescaler code 2: divider /16 */

  IWDG_KR  = 0x5555;

  IWDG_RLR = 0x04E2; /* 0x04E2 = 1250, f=40kHz, -> 1250 * 16 / 40000 = 500ms*/

  IWDG_KR  = 0xCCCC;

The IWDG is cyclic triggered by:

   IWDG_KR = 0xAAAA;

If the program runs into an infinite loop for testing the ''IWDGRSTF'' flag of the RCC_CSR register is set. But then the watchdog does not reset the controller, it still hungs in the infinite loop.

The both bits of the status register ''IWDG_SR'' (RVU, PVU) are not set the whole time.

Do you have any idea what I'm doing wrong? Thank you!

Best regards from Germany

FD

#stm32-iwdg-watchdog-problem
2 REPLIES 2
Posted on February 24, 2016 at 16:44

a) you're doing the test in a debugger, and there is some DBG MCU setting in effect.

b) you're driving the NRST pin high externally.

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David.Fabian
Associate II
Posted on February 25, 2016 at 15:31

Hi,

thank you, b) was the reason why it doesn't work! The NRST pin was connected directly to 3.3V. I think it should work with a series resistor between NRST and 3.3V.

Best regards

FD