Bit counter count of stm32f432

Everyone knows that stm32f4 has rich internal resources and powerful external peripherals. It has two 32-bit counters, which is very good for many projects that need to count pulses. It not only saves the expansion of external counters and saves PCB space, but also makes program design much simpler. Since I have just come into contact with the f4 series of microcontrollers, I just think it is very powerful. I also encountered problems in counting pulses with 32-bit counters. I also searched a lot of information on the Internet, but there are no specific routines for reference. I don’t have a deep understanding of registers, but I like library functions. Finally, after several days of hard thinking and many practices, I finally succeeded. The configuration file is posted as follows:

void TIM2_Int_Init(u32 arr,u16 psc)
{

TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
GPIO_InitTypeDef  GPIO_InitStructure;
// TIM_ICInitTypeDef  TIM_ICInitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2,ENABLE);  /
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
//PA0ÅäÖÃ
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_15;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;//100MHz
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; /
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN;//
  GPIO_Init(GPIOA, &GPIO_InitStructure);/

GPIO_PinAFConfig(GPIOA,GPIO_PinSource15,GPIO_AF_TIM2); //

  TIM_TimeBaseInitStructure.TIM_Period = arr; //
TIM_TimeBaseInitStructure.TIM_Prescaler=psc;  //
TIM_TimeBaseInitStructure.TIM_CounterMode=TIM_CounterMode_Up;
TIM_TimeBaseInitStructure.TIM_ClockDivision=TIM_CKD_DIV1; 
TIM_TimeBaseInit(TIM2,&TIM_TimeBaseInitStructure);//

TIM_TIxExternalClockConfig(TIM2, TIM_TIxExternalCLK1Source_TI1, TIM_ICPolarity_Rising, 0);
  
TIM_CounterModeConfig(TIM2,TIM_CounterMode_Up);
TIM_SetCounter(TIM2,0);//
TIM_Cmd(TIM2,ENABLE); //
}

The following is a function that sets timer 4 to read the count value for 1 second and prints it through the serial port:

void TIM4_IRQHandler(void)
{
if(TIM_GetITStatus(TIM4,TIM_IT_Update)==SET) /
{
       counter=TIM_GetCounter(TIM2);//Read the count value
printf("Fre:%32d ",counter);
TIM_SetCounter(TIM2,0);//Set the initial count value
counter=TIM_GetCounter(TIM2);//Confirm that the initial count value is 0
printf("Fre:%32d ",counter);
flag_1s=1;
}
TIM_ClearITPendingBit(TIM4,TIM_IT_Update); //
}

But in the end, I found that the counter counts inaccurately during actual testing. The larger the frequency, the greater the deviation. The value printed at 100KHz is about 99K, and at 1KHz it prints about 995. However, the count value can exceed 750KHz (actually measured). This is related to the automatic reload value and pre-scaling when the timer is initialized. I hope this helps you.