WWDG Clock source (PCLK1 Timer/Peripheral) for STM32L475?

[PBala.2]

From L475 datasheet and reference manual it was mentioned that the WWDG clock source is from PCLK1. Whether PCLK1 Timer or Peripheral clock is used for WWDG? I couldn't find the details..

Attached reference image from cubeMX

Thanks

[TDK]

WWDG is in APB1 and is clocked from PCLK1.

[PBala.2]

Thank you.

If it is PCLK1, then with below configuration of counter and window value I am trying to reload the counter every 2.5ms but the uC reset is happening because of the counter value is greater than window value. What could be the reason?

But if I configure the window and counter value(considering 36MHz) as (WWDG_CR_T_6 | 0x14) and (WWDG_CR_T_6 | 0x1D) respectively then it is working fine.

HCLK is 72 MHz

APB1 Prescaler is 4

PCLK1 is 18MHz

// Watchdog Window ((15 - 9) * 227) = 1.362

#define WWDG_WINDOW_VALUE (WWDG_CR_T6 | 0x09)

// Watchdog Counter ((14+1) * 227uS) = 3.41 mS

#define WWDG_COUNTER_VALUE (WWDG_CR_T6 | 0x0E)

void WWDG_Initialize(void)

{

  // Enable debug mode for WWDG

  DBGMCU->APB1FZR1 |= DBGMCU_APB1FZR1_DBG_WWDG_STOP;

  // Enable WWDG global interrupt.

  NVIC->ISER[0] |= NVIC_ISER_SETENA_0; 

  // Enable clock for windowed watchdog

  RCC->APB1ENR1 |= RCC_APB1ENR1_WWDGEN;

  

  // Set base prescaler to div. 1.

  WWDG->CFR &= ~WWDG_CFR_WDGTB;    

     

  // Reset window.

  WWDG->CFR &= ~WWDG_CFR_W;    

  

  // Preset window.

  WWDG->CFR |= (WWDG_CFR_W & WWDG_WINDOW_VALUE);

  WWDG->CR = WWDG_CR_WDGA | (WWDG_CR_T & WWDG_COUNTER_VALUE); 

  // Clear early wakeup flag.

  WWDG->SR = 0x00000000;  

  // Enable Early Wakeup interrupt.

  WWDG->CFR |= WWDG_CFR_EWI;

}

void WWDG_Reset(void)

{

  WWDG->CR = (WWDG_CR_T & WWDG_COUNTER_VALUE);

}