基本原理
PWM相关物理量的求法
呼吸灯代码
#include "stm32f10x.h" // Device header
#include "Delay.h"
TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
TIM_OCInitTypeDef TIM_OCInitStructuer;//结构体
GPIO_InitTypeDef GPIO_InitStructur;//定义变量结构体
void GPIOA_Init(void){
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
GPIO_InitStructur.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructur.GPIO_Pin = GPIO_Pin_0; //GPIO_Pin_15;
GPIO_InitStructur.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructur);
}
void PWM_Init(void){ //pwm波形配置
TIM_OCStructInit(&TIM_OCInitStructuer);//给不需要配置的结构体成员赋予初始值
TIM_OCInitStructuer.TIM_OCMode = TIM_OCMode_PWM1; //输出比较模式
TIM_OCInitStructuer.TIM_OCPolarity = TIM_OCPolarity_High; //极性
TIM_OCInitStructuer.TIM_OutputState = TIM_OutputState_Enable; //输出使能
TIM_OCInitStructuer.TIM_Pulse = 0; //CCR,频率1kHZ,占空比50%的PWM波形
TIM_OC1Init(TIM2, &TIM_OCInitStructuer);//配置GPIOA端口通道
}
/*定时器定时中断代码*/
void Timer_Init(void)//使用TM2定时器
{
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
GPIOA_Init();
TIM_InternalClockConfig(TIM2);
TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInitStructure.TIM_Period = 100 - 1; //ARR
TIM_TimeBaseInitStructure.TIM_Prescaler = 720 - 1; //PSC
TIM_TimeBaseInitStructure.TIM_RepetitionCounter = 0;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseInitStructure);
PWM_Init();
TIM_Cmd(TIM2, ENABLE);//启动定时器
}
/*CCR控制灯的亮度在运行过程中不断更改CCR的值来达到呼吸效果*/ //CCR[0~100]值越大灯越亮
void PWM_setcompare1(uint16_t compare){
TIM_SetCompare1(TIM2, compare);
}
uint8_t i;
int main(void){
Timer_Init();
while(1){
for(i = 0; i <= 100; i ++){
PWM_setcompare1(i);
Delay_ms(10);
}
for(i = 0; i <= 100; i ++){
PWM_setcompare1(100 - i);
Delay_ms(10);
}
}
}
注:TIM_OutputState 和 TIM_OutputNState不同
效果:
亮度会由暗变亮再变暗循环往复