[嵌入式]底层10.2——PWM实验复习

?PWM(蜂鸣器)框图

通过分析框图可知

1.分析RCC章节：相关控制器组使能

2.分析GPIO章节：复用模式/复用功能TIM4_CH1

3.分析TIM4章节：产生特定的方波?

?定时器工作原理

定时器工作原理：

1.当定时器启动之后，自动重载计数器中的值，会自动加载到递减计数器中

2.递减计数器在CK_CNT时钟驱动下进行工作

3.每来一个时钟周期，递减计数器中的值减1

4.当递减计数器中的值减到0的时候，自动重载计数器中的值，会再次自动加载到递减计数器中 --------------------如何产生PWM方波(比较/捕获寄存器)--------------------

1.当定时器启动之后，自动重载计数器中的值，会自动加载到递减计数器中

2.递减计数器在CK_CNT时钟驱动下进行工作

3.每来一个时钟周期，递减计数器中的值减1

4.如果减到和比较/捕获寄存器中的值相等之后，电平发生翻转，这样就可产生PWM方波信号

?pwm.h

#ifndef __PWM_H__
#define __PWM_H__
#include "stm32mp1xx_rcc.h"
#include "stm32mp1xx_gpio.h"
#include "stm32mp1xx_tim.h"

//蜂鸣器初始化　pb6-tim4_ch1
void tim_init();
//马达初始化   pf6-tim16_ch1
void mada_init();
//风扇初始化 pe9-time1_ch1
void fan_init();





#endif

pwm.c

#include "pwm.h"
void tim_init()
{
	//RCC_INIT
	RCC->MP_AHB4ENSETR |= (0x1<<1);
	RCC->MP_APB1ENSETR |= (0x1<<2);
	
	//GPIO_INIT
	GPIOB->MODER &= (~(0x3<<12));
	GPIOB->MODER |= (0x2<<12);
	GPIOB->AFRL &= (~(0xf<<24));
	GPIOB->AFRL |= (0x2<<24);

	//TIM_INIT
	//设置分频器
	TIM4->PSC = (208);
	//设PWM方波占空比 对比较/捕获寄存器进行赋值
	TIM4->CCR1 =(700);
	//设置PWM方波最终周期
	TIM4->ARR =(1000);
	
	TIM4->CR1 |= (0x1<<7);
	TIM4->CR1 &= (~(0x3<<5));
	TIM4->CR1 |=(0x1<<4);
	TIM4->CR1 |=(0x1<<0);

	TIM4->CCMR1 &=(~(0x1<<16));
	TIM4->CCMR1 &=(~(0x7<<4));
	TIM4->CCMR1 |=(0x6<<4);
	TIM4->CCMR1 |=(0x1<<3);
	TIM4->CCMR1 &=(~(0x3<<0));

	TIM4->CCER &=(~(0x1<<3));
	TIM4->CCER &=(~(0x1<<1));
	TIM4->CCER |=(0x1<<0);
	




}
//马达初始化   pf6-tim16_ch1
void mada_init()
{
	RCC->MP_AHB4ENSETR |=0X1<<5;                    
    RCC->MP_APB2ENSETR |=0X1<<3;                    
                                                    
    GPIOF->MODER &=(~(0X3<<12));                    
    GPIOF->MODER |=(0X1<<13);                       
                                                    
    GPIOF->AFRL &=(~(0XF<<24));                     
    GPIOF->AFRL |=0X1<<24;  
	
	//TIM_INIT
	//设置分频器
	TIM16->PSC = (208);
	//设置PWM方波最终周期
	TIM16->CCR1 =(700);
	//设PWM方波占空比 对比较/捕获寄存器进行赋值
	TIM16->ARR =(1000);

	TIM16->CR1 |= (0x1<<7);
	TIM16->CR1 &= (~(0x3<<5));
	TIM16->CR1 |=(0x1<<4);
	TIM16->CR1 |=(0x1<<0);

	TIM16->CCMR1 &=(~(0x1<<16));
	TIM16->CCMR1 &=(~(0x7<<4));
	TIM16->CCMR1 |=(0x6<<4);
	TIM16->CCMR1 |=(0x1<<3);
	TIM16->CCMR1 &=(~(0x3<<0));

	TIM16->CCER &=(~(0x1<<3));
	TIM16->CCER &=(~(0x1<<1));
	TIM16->CCER |=(0x1<<0);

	TIM16->BDTR |=(0x1<<15);
	 
}
//风扇初始化 pe9-time1_ch1
void fan_init()
{
	RCC->MP_AHB4ENSETR |=0X1<<4;                    
    RCC->MP_APB2ENSETR |=0X1<<0;                    
                                                    
    GPIOE->MODER &=(~(0X3<<18));                    
    GPIOE->MODER |=(0X1<<19);                       
                                                    
    GPIOE->AFRH &=(~(0XF<<4));                     
    GPIOE->AFRH |=0X1<<4;  
	
	//TIM_INIT
	//设置分频器
	TIM1->PSC = (208);
	//设置PWM方波最终周期
	TIM1->CCR1 =(700);
	//设PWM方波占空比 对比较/捕获寄存器进行赋值
	TIM1->ARR =(1000);

	TIM1->CR1 |= (0x1<<7);
	TIM1->CR1 &= (~(0x3<<5));
	TIM1->CR1 |=(0x1<<4);
	TIM1->CR1 |=(0x1<<0);

	TIM1->CCMR1 &=(~(0x1<<16));
	TIM1->CCMR1 &=(~(0x7<<4));
	TIM1->CCMR1 |=(0x6<<4);
	TIM1->CCMR1 |=(0x1<<3);
	TIM1->CCMR1 &=(~(0x3<<0));

	TIM1->CCER &=(~(0x1<<3));
	TIM1->CCER &=(~(0x1<<1));
	TIM1->CCER |=(0x1<<0);

	TIM1->BDTR |=(0x1<<15);

}

main.c

#include "pwm.h"



extern void printf(const char *fmt, ...);

void delay_ms(int ms)

{

	int i,j;

	for(i = 0; i < ms;i++)

		for (j = 0; j < 1800; j++);

}





int main()

{

	tim_init();

	mada_init();

	fan_init();

	while(1)

	{

			

	}

	return 0;

}