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pwm input mode low frequncy

saba ghorbani

hi

i work with stm32f107

pleas answer me

how i can measure frequency in 50 hz with input pwm

i read about it and find out i can measure frequency with input pwm up to 1100
but input pwm have TIM_ICPrescaler that i think devide pwm frequncy

it is true ?

if no , please say me how i can measure 50 hz?

Parents
  • 0 in reply to Andy Neil

    thanks for your answer

    i get pwm with micero controller and i wanted measure frequncy and duty cycle and i can measure 1100 hz

    i have some problem please answer me :

    this is my code :

      NVIC_InitStructure.NVIC_IRQChannel                   = TIM2_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority =0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority        =1;
  NVIC_InitStructure.NVIC_IRQChannelCmd                = ENABLE;
  NVIC_Init(&NVIC_InitStructure);

        TIM_ICInitStructure.TIM_Channel       = TIM_Channel_1;
  TIM_ICInitStructure.TIM_ICPolarity    = TIM_ICPolarity_Rising;
  TIM_ICInitStructure.TIM_ICSelection   = TIM_ICSelection_DirectTI;
  TIM_ICInitStructure.TIM_ICPrescaler   = TIM_ICPSC_DIV1;
  TIM_ICInitStructure.TIM_ICFilter      = 0x0;
  TIM_ICInit(TIM3, &TIM_ICInitStructure);
  TIM_PWMIConfig(TIM2, &TIM_ICInitStructure);
  TIM_SelectInputTrigger(TIM2,TIM_TS_TI1FP1);

  TIM_SelectSlaveMode(TIM2, TIM_SlaveMode_Reset);

  TIM_SelectMasterSlaveMode(TIM2,TIM_MasterSlaveMode_Enable);

  TIM_Cmd(TIM2, ENABLE);
  TIM_ITConfig(TIM2,TIM_IT_CC1,ENABLE);

    and this is my handler :

    {

        GPIO_SetBits(GPIOC,GPIO_Pin_2);

  TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);

        IC2Value = TIM_GetCapture1(TIM2);
//      IC1=TIM_GetCapture1(TIM2);
//      IC2=TIM_GetCapture2(TIM2);
         if (IC2Value != 0)
  {
    /* Duty cycle computation */
    DutyCycle = (TIM_GetCapture2(TIM2) * 100) / IC2Value;
    /* Frequency computation */
    Frequency = SystemCoreClock / IC2Value;
                IC2Value=0;
  }
  else
  {
    DutyCycle = 0;
    Frequency = 0;
  }
}

    please say when during the current code i go to this handler

Reply
  • 0 in reply to Andy Neil

    thanks for your answer

    i get pwm with micero controller and i wanted measure frequncy and duty cycle and i can measure 1100 hz

    i have some problem please answer me :

    this is my code :

      NVIC_InitStructure.NVIC_IRQChannel                   = TIM2_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority =0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority        =1;
  NVIC_InitStructure.NVIC_IRQChannelCmd                = ENABLE;
  NVIC_Init(&NVIC_InitStructure);

        TIM_ICInitStructure.TIM_Channel       = TIM_Channel_1;
  TIM_ICInitStructure.TIM_ICPolarity    = TIM_ICPolarity_Rising;
  TIM_ICInitStructure.TIM_ICSelection   = TIM_ICSelection_DirectTI;
  TIM_ICInitStructure.TIM_ICPrescaler   = TIM_ICPSC_DIV1;
  TIM_ICInitStructure.TIM_ICFilter      = 0x0;
  TIM_ICInit(TIM3, &TIM_ICInitStructure);
  TIM_PWMIConfig(TIM2, &TIM_ICInitStructure);
  TIM_SelectInputTrigger(TIM2,TIM_TS_TI1FP1);

  TIM_SelectSlaveMode(TIM2, TIM_SlaveMode_Reset);

  TIM_SelectMasterSlaveMode(TIM2,TIM_MasterSlaveMode_Enable);

  TIM_Cmd(TIM2, ENABLE);
  TIM_ITConfig(TIM2,TIM_IT_CC1,ENABLE);

    and this is my handler :

    {

        GPIO_SetBits(GPIOC,GPIO_Pin_2);

  TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);

        IC2Value = TIM_GetCapture1(TIM2);
//      IC1=TIM_GetCapture1(TIM2);
//      IC2=TIM_GetCapture2(TIM2);
         if (IC2Value != 0)
  {
    /* Duty cycle computation */
    DutyCycle = (TIM_GetCapture2(TIM2) * 100) / IC2Value;
    /* Frequency computation */
    Frequency = SystemCoreClock / IC2Value;
                IC2Value=0;
  }
  else
  {
    DutyCycle = 0;
    Frequency = 0;
  }
}

    please say when during the current code i go to this handler

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