How to solve the frequency of pwm generated by Stm32?

Question one:

//TIM2 pre-scaling setting: 1MHZ, APB1 division factor 2, input to TIM3 clock is 36MHzx2 = 72MHz  

TIM_PrescalerConfig(TIM2,71, TIM_PSCReloadMode_Immediate);

void TIM_PrescalerConfig(TIM_TypeDef* TIMx, uint16_t Prescaler, uint16_t TIM_PSCReloadMode)

{

  /* Check the parameters */

  assert_param(IS_TIM_ALL_PERIPH(TIMx));

  assert_param(IS_TIM_PRESCALER_RELOAD(TIM_PSCReloadMode));

  /* Set the Prescaler value */

  TIMx->PSC = Prescaler;

  /* Set or reset the UG Bit */

  TIMx->EGR = TIM_PSCReloadMode;

}

When set to change immediately, that is, UG is set to 1, an update event is generated immediately and the frequency division coefficient changes.

The previous statement is equivalent to

TIM_TimeBaseStructure.TIM_Prescaler = 71;

At this time, the counting frequency of CNT is 1MHZ

Question 2:

TIM_TimeBaseStructure.TIM_Period = 1000;  //1KHz

The above statement sets the auto-reload value to 999, which is the ARR value.

After this statement, the frequency of pwm is 1kHz

How to calculate it? It is very simple, 1M/1000 = 1kHz

One cycle of PWM is when the counter counts from 0 to ARR, that is, it takes 1000 times to complete one cycle.

Question 3:

 uint16_t TIM_Pulse;         /*!< Specifies the pulse value to be loaded into the Capture Compare Register.

                                   This parameter can be a number between 0x0000 and 0xFFFF */

Equivalent to

void TIM_SetCompare2(TIM_TypeDef* TIMx, uint16_t Compare2)

Both set the value of the CCR register