PWM输出波形低电平不是0

风吹裙底屁屁凉 · 发表于 2016-1-15 15:16:09

本帖最后由风吹裙底屁屁凉于 2016-1-17 20:02 编辑

用STM32 输出PWM 示波器测试波形低电平有1.24V，而且波形有好多毛刺，但是电源测试波形很好。

void TIM4_PWM_Config()
{
GPIO_InitTypeDef GPIO_InitStructure;

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
   // PB8-> TIM4_CH3  PWM输出
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOB, &GPIO_InitStructure);

TIM_TimeBaseStructure.TIM_Period = 99;
TIM_TimeBaseStructure.TIM_Prescaler = 71;
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM4, & TIM_TimeBaseStructure);

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
//TIM_OCInitStructure.TIM_Pulse = 20;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OC3Init(TIM4, & TIM_OCInitStructure);

TIM_OC3PreloadConfig(TIM4, TIM_OCPreload_Enable);

TIM_Cmd(TIM4, ENABLE);

}

这是配置定时器代码芯片是stm32vet6  用的是PB8复用功能TIM4的chinal3
主函数里边除了初始化只有这一段代码  TIM_SetCompare3(TIM4, 60);