PWM output based on STM32

c) Initialization function definition:
void TIM_Configuration(void); //Define TIM initialization function
d) Initialization function call:
TIM_Configuration(); //TIM initialization function call
e) Initialization function, different from the previous module, TIM initialization is divided into two parts - basic initialization and channel initialization:
void TIM_Configuration(void) //TIM initialization function
{ 
  TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure; //Timer initialization structure
  TIM_OCInitTypeDef TIM_OCInitStructure; //Channel output initialization structure

//TIM3 initialization
  TIM_TimeBaseStructure.TIM_Period = 0xFFFF; //Period 0~FFFF
  TIM_TimeBaseStructure.TIM_Prescaler = 5; //Clock division
  TIM_TimeBaseStructure.TIM_ClockDivision = 0; //Clock division
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //ModeTIM_TimeBaseInit
  (TIM3, &TIM_TimeBaseStructure); //Basic initializationTIM_ITConfig
  (TIM3, TIM_IT_CC4, ENABLE); //Turn on interrupt, interrupt needs this line of code
  
//TIM3 channel initializationTIM_OCStructInit
  (& TIM_OCInitStructure); //Default
  parametersTIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; //Working stateTIM_OCInitStructure.TIM_OutputState
  = TIM_OutputState_Enable; //Set to output, this line of code is required for PWM outputTIM_OCInitStructure.TIM_Pulse
  = 0x2000; //Duty lengthTIM_OCInitStructure.TIM_OCPolarity
  = TIM_OCPolarity_High; //High levelTIM_OC4Init
  (TIM3, &TIM_OCInitStructure); //Channel initialization

  TIM_Cmd(TIM3, ENABLE); //Start TIM3
}

f) Add TIM clock start in RCC initialization function:
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM3, ENABLE);
g) Set the input and output pin modes in GPIO. Signal: AF_PP, 50MHz.
h) If you use interrupts, add the following code to NVIC:

//Open TIM2 interrupt
  NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQChannel; //Channel
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 3; //Preemption level
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1; //Response level
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //Start
  NVIC_Init(&NVIC_InitStructure); //Initialization

Interrupt code:
void TIM2_IRQHandler(void)
{
  if (TIM_GetITStatus(TIM2, TIM_IT_CC4) != RESET) //Judge the interrupt source
  {
    TIM_ClearITPendingBit(TIM2, TIM_IT_CC4); //Clear interrupt flag
    GPIO_WriteBit(GPIOB, GPIO_Pin_11, (BitAction)(1-GPIO_ReadOutputDataBit(GPIOB, GPIO_Pin_11)));//Change LED color
    IC4value = TIM_GetCapture4(TIM2); //Get captured value
  }  
}

i) Simple application:
//Change duty cycle
TIM_SetCompare4(TIM3, variable);

j) Note:
The IO output mode of the pin is determined according to the application. For example, if PWM output is used to drive the LED, the corresponding pin should be set to AF_PP, otherwise the microcontroller will have no output.