STM32 - PWM output

    Pulse Width Modulation, or PWM for short, is a method of using digital signals to output analog signals. It has multiple modes. The main principle is to use the periodic changes in the high and low levels of digital signals to change the average value of the output voltage, thereby achieving the output mode of analog signals. It is mainly used in motor speed regulation and dimming lamp circuit control. 

    There are multiple PWM signals in STM32. Each timer output pin can be set to the output of the corresponding PWM signal. There are two main parameters of PWM signal, the duty cycle of the cycle. The cycle is mainly determined by the corresponding timer. The duty cycle is the time when the PWM outputs a high level. Assuming that the current timing cycle is 2MS, in 2MS, by setting 1MS pin to output a high level. In this way, it can be said that the duty cycle of this PWM is 50%. 

    During program execution, you can use TIM_SetCompare1() to change the corresponding duty cycle, so that you can flexibly control the output of the PWM signal.

#include "Time.h"

#include "stm32f10x.h"

void TIM4_init(void)

{

    GPIO_InitTypeDef GPIO_InitStruc; 

    TIM_TimeBaseInitTypeDef TIM_struct;

    TIM_OCInitTypeDef TIM_ocinit;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB,ENABLE);

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

    GPIO_InitStruc.GPIO_Mode=GPIO_Mode_AF_PP;                         

    GPIO_InitStruc.GPIO_Pin=GPIO_Pin_6 | GPIO_Pin_7 | GPIO_Pin_8| GPIO_Pin_9;

    GPIO_InitStruc.GPIO_Speed=GPIO_Speed_50MHz;

    GPIO_Init(GPIOB,&GPIO_InitStruc); //Initialize the output pin of the PWM signal

    GPIO_InitStruc.GPIO_Mode=GPIO_Mode_Out_PP;                         

    GPIO_InitStruc.GPIO_Pin=GPIO_Pin_0 | GPIO_Pin_1;

    GPIO_InitStruc.GPIO_Speed=GPIO_Speed_50MHz;

    GPIO_Init(GPIOA,&GPIO_InitStruc);   

    TIM_struct.TIM_Period=999; //Set the timer period 72/72*1000 to 1MS

    TIM_struct.TIM_CounterMode=TIM_CounterMode_Up;

    TIM_struct.TIM_ClockDivision=TIM_CKD_DIV1 ;

    TIM_struct.TIM_Prescaler=71; //Timer 72 division

    TIM_TimeBaseInit(TIM4,&TIM_struct);

    //TIM_ITConfig(TIM4,TIM_IT_Update,ENABLE);

    TIM_ocinit.TIM_OCMode=TIM_OCMode_PWM1; //Set PWM mode to 1

    TIM_ocinit.TIM_Pulse=200; //Set the initial PWM duty cycle

    TIM_ocinit.TIM_OutputState=TIM_OutputState_Enable; //Enable pWM output enable

    TIM_ocinit.TIM_OCPolarity=TIM_OCPolarity_High; //Set PWM signal polarity

    TIM_OC1Init(TIM4,&TIM_ocinit);

    TIM_OC1PreloadConfig(TIM4, TIM_OCPreload_Enable);

    TIM_OC2Init(TIM4,&TIM_ocinit);

    TIM_OC2PreloadConfig(TIM4, TIM_OCPreload_Enable);

    TIM_OC3Init(TIM4,&TIM_ocinit);

    TIM_OC3PreloadConfig(TIM4, TIM_OCPreload_Enable);

    TIM_OC4Init(TIM4,&TIM_ocinit);

    TIM_OC4PreloadConfig(TIM4, TIM_OCPreload_Enable);

    TIM_Cmd(TIM4,ENABLE);

}

void TIM_PWM_Con(u16 DR1,u16 DR2,u16 DR3,u16 DR4)

{

    TIM_SetCompare1(TIM4,DR1); //Change the duty cycle of PWM

    TIM_SetCompare2(TIM4,DR2);

    TIM_SetCompare3(TIM4,DR3);

    TIM_SetCompare4(TIM4,DR4);

}