stm32 pwm输出问题

饮马南山 · 发表于 2012-12-24 18:43:36

大家好，做PWM输出控制，上电时即输出高电平，在关断PWM输出时，也始终输出为高电平。而要求是高电平有效，即关断情况下是低电平才对
也改过如下配置极性，也没有效果。请大家帮忙看看哪里配置出了问题，谢谢
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;
    TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset;
    TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCNIdleState_Reset;

//PWM输出配置
void PWM_Config(void)
{
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_OCInitTypeDef TIM_OCInitStructure;
    TIM_BDTRInitTypeDef TIM_BDTRInitStructure;

   /* TIM8 clock enable */
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);

    /* Time Base configuration */
    // ARR = TIM1CLK / ChopperFreq ChopperFreq:16KHz
    TIM_TimeBaseStructure.TIM_Prescaler = 0;    //预分频 PSC
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseStructure.TIM_Period = PWM_PERIOD - 1;
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;
    TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);


/* Channel 1, 2,3 and 4 Configuration in PWM mode */
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;            //TIM输出通道初始化
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_OutputNState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = CH1_PULSE;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;
    TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset;
    TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCNIdleState_Reset;
    TIM_OC1Init(TIM1, &TIM_OCInitStructure);

    TIM_OCInitStructure.TIM_Pulse = CH2_PULSE;
    TIM_OC2Init(TIM1, &TIM_OCInitStructure);

    TIM_OCInitStructure.TIM_Pulse = CH3_PULSE;
    TIM_OC3Init(TIM1, &TIM_OCInitStructure);

/* Automatic Output enable, Break, dead time and lock configuration*/
    TIM_BDTRInitStructure.TIM_OSSRState = TIM_OSSRState_Enable; //死区刹车初始化
    TIM_BDTRInitStructure.TIM_OSSIState = TIM_OSSIState_Enable;
    TIM_BDTRInitStructure.TIM_LOCKLevel = TIM_LOCKLevel_OFF;
    TIM_BDTRInitStructure.TIM_DeadTime = 12; // DeadTime[ns] = value * (1/SystemCoreFreq) (on 120MHz: 12 is 100ns)
    TIM_BDTRInitStructure.TIM_Break = TIM_Break_Enable;
    TIM_BDTRInitStructure.TIM_BreakPolarity = TIM_BreakPolarity_High;//TIM_BreakPolarity_Low;
    TIM_BDTRInitStructure.TIM_AutomaticOutput = TIM_AutomaticOutput_Enable;//TIM_AutomaticOutput_Disable;
    TIM_BDTRConfig(TIM1, &TIM_BDTRInitStructure);

    //TIM_CCPreloadControl(TIM1, ENABLE); //使能捕获比较寄存器预装载
    TIM_OC1PreloadConfig(TIM1,TIM_OCPreload_Enable);      //使能捕获比较寄存器预装载（通道1）
    TIM_OC2PreloadConfig(TIM1,TIM_OCPreload_Enable);    //使能捕获比较寄存器预装载（通道2）
    TIM_OC3PreloadConfig(TIM1,TIM_OCPreload_Enable);    //使能捕获比较寄存器预装载（通道3）

    //TIM_ITConfig(TIM1, TIM_IT_COM, ENABLE);   //使能COM事件中断

    TIM_SelectInputTrigger(TIM1, TIM_TS_ITR0); //输入触发源选择TIM5

    /* TIM1 counter enable */
    //TIM_Cmd(TIM1, ENABLE);

    /* Main Output Enable */
    TIM_CtrlPWMOutputs(TIM1, ENABLE);
}

//以下参考官方库6步方波示例
void TIM1_TRG_COM_TIM11_IRQHandler(void)
{
/* Clear TIM1 COM pending bit */
TIM_ClearITPendingBit(TIM1, TIM_IT_COM);

if (step == 1)
{
    /* Channel3 configuration */
    TIM_CCxCmd(TIM1, TIM_Channel_3, TIM_CCx_Disable);
    TIM_CCxNCmd(TIM1, TIM_Channel_3, TIM_CCxN_Disable);

    /* Channel1 configuration */
    TIM_SelectOCxM(TIM1, TIM_Channel_1, TIM_OCMode_PWM1);
    TIM_CCxCmd(TIM1, TIM_Channel_1, TIM_CCx_Enable);
    TIM_CCxNCmd(TIM1, TIM_Channel_1, TIM_CCxN_Disable);

    /* Channel2 configuration */
    //TIM_SelectOCxM(TIM1, TIM_Channel_2, TIM_OCMode_Active );
    TIM_CCxCmd(TIM1, TIM_Channel_2, TIM_CCx_Disable);
    TIM_CCxNCmd(TIM1, TIM_Channel_2, TIM_CCxN_Enable);
    //step++;
}
    .......
}

以上

正点原子 · 发表于 2012-12-24 21:30:58

直接配置,没试过,不知道可以不.
有个傻逼的办法,直接控制IO方向.
输出PWM的时候,设置为复用输出.结束PWM输出的时候,设置为推挽输出,直接软件控制IO电平

饮马南山 · 发表于 2012-12-25 09:56:27

回复【2楼】正点原子:

直接配置,没试过,不知道可以不.
有个傻逼的办法,直接控制IO方向.
输出PWM的时候,设置为复用输出.结束PWM输出的时候,设置为推挽输出,直接软件控制IO电平

---------------------------------
PWM输出及关停过程中倒可以通过强制输出有/无效电平
关键是，发现将几个IO口配置成复用PWM输出脚(推挽输出高有效)，在不开定时器，不输出，都会变成高电平。也就是说配置完就成高电平了，纳闷