STM32 PWM output experiment

First, some necessary declarations

#include 
#include "pwm.h"u32 Sys_Clk=1000000;u16 pwm1_2_Freqz;//Frequency of pwm wave 1, 2 output port u16 pwm3_4_Freqz;//Frequency of pwm wave 3, 4 output port u16 TIM2_PERIOD;//Number of timer jump cycles u16 TIM4_PERIOD;u16 CCR_VAL1;//Value of the timer comparison register, when the actual value is greater than this value, the level is inverted u16 CCR_VAL2; u16 CCR_VAL3; u16 CCR_VAL4; 123456789101112

Below is the main text... The notes are all typed by hand (≧▽≦)/

void PWM_GPIO_Config(void) //Function used to configure peripheral functions, always ends with the string "Config" {
    GPIO_InitTypeDef GPIO_InitStructure; //PPP_InitTypeDef: Initialize the peripheral named PPP, here is to initialize GPIO

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA|RCC_APB2Periph_GPIOB|RCC_APB2Periph_AFIO,ENABLE);//Turn on the clock, status: ENABLE means enabled. Periph means peripheral device in Chinese. Initialize GPIO AB port, multiplex push-pull output

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2,ENABLE); //Turn on TIM2 clock For the classification of APB1 and APB2, see Figure 1 and Figure 2

    GPIO_InitStructure.GPIO_Pin=GPIO_Pin_2|GPIO_Pin_3; //Initialize pins 2,3
    GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF_PP; //Select one of the enumeration types
    GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz; //Frequency 50 MHz
    GPIO_Init(GPIOA,&GPIO_InitStructure); //Initialize port A

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4,ENABLE); //Turn on TIM4 clock

    /*Configure PB8 and PB9 to multiplex push-pull mode*/
    GPIO_InitStructure.GPIO_Pin=GPIO_Pin_8|GPIO_Pin_9; //Same as before
    GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
    GPIO_Init(GPIOB,&GPIO_InitStructure);
}123456789101112131415161718192021

 
OK. We just configured the GPIO pins for the pwm output. 
Next we configure the pwm clock.

void PWM_Mode_Config(void)//Configure pwm mode {
        TIM4_PERIOD=Sys_Clk/pwm1_2_Freqz; //Timer jump cycle number = system clock cycle/pwm output frequency
    TIM2_PERIOD=Sys_Clk/pwm3_4_Freqz;

    CCR_VAL1=CCR_VAL2=TIM4_PERIOD>>1; //Shift operation to make the value of the comparison register equal to half of the jump cycle number, and obtain a PWM wave with a duty cycle of 50%
        CCR_VAL3=CCR_VAL4=TIM2_PERIOD>>1; /*Timer (ie TIM) initialization*/
    TIM_TimeBaseStructure.TIM_Period = TIM4_PERIOD; //Set the period value to be loaded into the auto-reload register in the next update event, for TIM4
    TIM_TimeBaseStructure.TIM_Prescaler=72; //Prescaler value
    TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1; //Clock division
    TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; //Upward counting mode

    TIM_TimeBaseInit(TIM4, & TIM_TimeBaseStructure); //Initialize TIM4 according to the parameters specified in TIM_TimeBaseStructure

    TIM_TimeBaseStructure.TIM_Period = TIM2_PERIOD; //Set the period value to be loaded into the auto-reload register in the next update event, for TIM4. Other parameters are the same as TIM2, so they are not set again.
    TIM_TimeBaseInit(TIM2, & TIM_TimeBaseStructure); //Initialize TIM2 according to the parameters specified in TIM_TimeBaseStructure

    /*Timer output mode initialization*/
    TIM_OCInitStruct.TIM_OCMode=TIM_OCMode_PWM1; //TIM_OCInitStruct is after TIM_OCInitTypeDef (Figure 3), the structure has multiple parameters. This line sets the pulse width modulation mode 1
    TIM_OCInitStruct.TIM_OutputState=TIM_OutputState_Enable; //Comparison output enable
    TIM_OCInitStruct.TIM_Pulse=CCR_VAL4; //Set duty cycle to 50%
    TIM_OCInitStruct.TIM_OCPolarity=TIM_OCPolarity_High; //Set the effective polarity, that is, set the effective level of the comparison output. Here it is set to high level effective. When the timer compares and matches, the output port outputs a high level

    TIM_OC3Init(TIM2,&TIM_OCInitStruct); //Initialize TIM2 channel 3 (pwm4)
    TIM_OC3PreloadConfig(TIM2,TIM_OCPreload_Enable); //After initializing OCX, configure the preload register of OCX and enable it.

    TIM_OCInitStruct.TIM_OutputState=TIM_OutputState_Enable; //Comparison output enable
    TIM_OCInitStruct.TIM_Pulse=CCR_VAL3; //Set duty cycle to 50%

    TIM_OC4Init(TIM2,&TIM_OCInitStruct); //Initialize TIM2 channel 4 (pwm3)
    TIM_OC4PreloadConfig(TIM2,TIM_OCPreload_Enable); //Configure the preload register of OC4

    TIM_OCInitStruct.TIM_OutputState=TIM_OutputState_Enable; //Comparison output enable
    TIM_OCInitStruct.TIM_Pulse=CCR_VAL2; //Set duty cycle to 50%

    TIM_OC3Init(TIM4,&TIM_OCInitStruct); //Initialize TIM4 channel 3 (pwm2)
    TIM_OC3PreloadConfig(TIM4,TIM_OCPreload_Enable); //Configure the preload register of OC3

    TIM_OCInitStruct.TIM_OutputState=TIM_OutputState_Enable; //Comparison output enable
    TIM_OCInitStruct.TIM_Pulse=CCR_VAL1; //Set duty cycle to 50%

    TIM_OC4Init(TIM4,&TIM_OCInitStruct);/Initialize TIM4 channel 4 (pwm1)
    TIM_OC4PreloadConfig(TIM4,TIM_OCPreload_Enable); //Configure the preload register of OC4

    TIM_ARRPreloadConfig(TIM2, ENABLE); //After configuring all channels, enable automatic reload registers, two parameters: TIMx, NewState
    TIM_ARRPreloadConfig(TIM4, ENABLE);//Same as above


    TIM_Cmd(TIM2,ENABLE); //Finally, don't forget to Cmd the peripheral (enable), this is the last step of all peripheral operations
    TIM_Cmd(TIM4,ENABLE);//Same as above}1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253

The first two functions are a bit confusing... I have written so many that I don’t even know what they do. Here is a better encapsulated one... written by a senior...

void TIM1_PWM_Init(void)
 {
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure; //Necessary declaration
    TIM_OCInitTypeDef TIM_OCInitStructure;
    GPIO_InitTypeDef GPIO_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);
    GPIO_InitStructure.GPIO_Pin=GPIO_Pin_11 | GPIO_Pin_8;
    GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
    GPIO_Init(GPIOA,&GPIO_InitStructure);

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1,ENABLE);

    TIM_TimeBaseStructure.TIM_Period=19999;
    TIM_TimeBaseStructure.TIM_Prescaler=71;
    TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM1,&TIM_TimeBaseStructure);

    TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1;
    TIM_OCInitStructure.TIM_OutputState=TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse=1000; 
    TIM_OCInitStructure.TIM_OCPolarity=TIM_OCPolarity_High; 

    TIM_OC4Init(TIM1,&TIM_OCInitStructure);
    TIM_OC4PreloadConfig(TIM1,TIM_OCPreload_Enable);
    TIM_OCInitStructure.TIM_Pulse=2000; 
    TIM_OC1Init(TIM1,&TIM_OCInitStructure);
    TIM_OC1PreloadConfig(TIM1,TIM_OCPreload_Enable);
    TIM_CtrlPWMOutputs(TIM1,ENABLE);

    TIM_ARRPreloadConfig(TIM1,ENABLE);

    TIM_Cmd(TIM1,ENABLE);}1234567891011121314151617181920212223242526272829303132333435363738

Well, let's simulate it! 
Add pins and set thresholds, and you'll see the following analysis window: 

Correct!