STM32 Study Notes---IWDG Independent Watchdog Experiment

After doing the WWDG window watchdog experiment, we continued with the 9th experiment - IWDG independent watchdog experiment. In this experiment, we set the window watchdog IWDG interrupt time to regularly check whether there is an error. In the SysTick_Handler interrupt function, a running light is added to test whether the IDWG watchdog program is running. The feasibility of the program is verified by flashing PD6-LED2. The programming project is roughly the same as the USART experiment process. First, turn on the system clock, then the GPIO port clock, then the multiplexing function clock AFIO, and then the clock used by each module. After that, enter the initialization, setting, and writing of each module. For interrupts, fill in the interrupt trigger processing function of a certain module in the interrupt function. The important thing is to turn on the module declaration in the CONFG.H function. That's about it.

The following are the main parts of the IWDG function:

//IWDG window watchdog setting initialization
void IWDG_Config(void)
{ 
 //Independent watchdog initialization
  IWDG_WriteAccessCmd(IWDG_WriteAccess_Enable); //Start register reading and writing

  IWDG_SetPrescaler(IWDG_Prescaler_32); //40K clock divided by 32

  IWDG_SetReload(349);                 //Counter value

  IWDG_ReloadCounter();             //Restart counter

  IWDG_Enable();                       //Start watchdog
}
***************************************************************

Precautions:

i. If you have a dog, you can ignore it normally, but don’t forget to feed it, otherwise it will die without knowing how!

ii. The initialization program must be called after systic is initialized.

iii. The independent watchdog needs to be fed by the systic interrupt, but systic can't just do this, so I wrote the following code, which will not affect other applications of systic. Other systic cycle codes can also be used for reference:

Step 1: Define variables in stm32f10x_it.c

int Tic_IWDG;           //Frequency determination variable of dog feeding cycle program

Step 2: Change the dog feeding code in SysTickHandler to the following:

Tic_IWDG++;          //Variable increment

if(Tic_IWDG>=100)    //feed the dog every 100 systic cycles

{   IWDG_ReloadCounter(); //Restart counter (feed the dog)

  Tic_IWDG=0;       // variable clear

}

The complete code is

void SysTick_Handler(void)
{
 Tic_Val++;           //Precise delay variable increment

 Tic_IWDG++;          //Independent watchdog variable increment

 if(Tic_IWDG>=100)    //feed the dog every 100 systic cycles

 {   
   IWDG_ReloadCounter(); //Restart counter (feed the dog)
   Tic_IWDG=0;       //Clear the variable

 switch(IWDGFLAG)
 {
 case 0:
  GPIO_SetBits(GPIOD, GPIO_Pin_6);
    break;
 case 1:
  GPIO_ResetBits(GPIOD, GPIO_Pin_6);
    break;
 default:
    break;
 }
 IWDGFLAG=!IWDGFLAG;

 }
}
The following is the result of the IWDG function: