PWM波,我用的定时器通道2,怎么一直输出低电平啊

小怪兽 · 发表于 2016-7-10 16:20:10

#include "pwm.h"
void TIM2_PWM_Init(u16 arr,u16 psc)
{
GPIO_InitTypeDef GPIO_InitStruct;
TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStruct;
TIM_OCInitTypeDef TIM_OCInitStruct;

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA|RCC_APB2Periph_AFIO ,ENABLE);

  GPIO_InitStruct.GPIO_Pin=GPIO_Pin_1;                      //PA1
  GPIO_InitStruct.GPIO_Speed=GPIO_Speed_50MHz;             //50MHZ的输出速度
  GPIO_InitStruct.GPIO_Mode=GPIO_Mode_AF_PP;                //复用推挽输出
  GPIO_Init(GPIOA,&GPIO_InitStruct);

  TIM_TimeBaseInitStruct.TIM_Prescaler=arr;                      //设置作为时钟频率除数的预分频值
  TIM_TimeBaseInitStruct.TIM_CounterMode=TIM_CounterMode_Up; //设置为向上计数
  TIM_TimeBaseInitStruct.TIM_Period=psc;                         //设置在下一个更新事件装入活动的自动重装载寄存器周期的值
  TIM_TimeBaseInitStruct.TIM_ClockDivision=0;    //设置时钟分割
  TIM_TimeBaseInit(TIM2,&TIM_TimeBaseInitStruct);

  TIM_OCInitStruct.TIM_OCMode=TIM_OCMode_PWM1;             //设置为PWM模式1
  TIM_OCInitStruct.TIM_OutputState=TIM_OutputState_Enable;  //比较输出使能1
  TIM_OCInitStruct.TIM_OCPolarity=TIM_OCPolarity_High;    //TIM比较输出极性高
  TIM_OCInitStruct.TIM_Pulse=0;
  TIM_OC2Init(TIM2,&TIM_OCInitStruct);

  TIM_OC2PreloadConfig(TIM2,TIM_OCPreload_Enable);  //使能预装载值

  TIM_Cmd(TIM2, ENABLE);    //使能TIM2

  TIM_SetCompare2(TIM2,0);
}