why cant I get PWM at TIM3 ?

[mehmet.karakaya]

Posted on July 04, 2011 at 19:03

void TIM3init(void) {

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0|GPIO_Pin_1;

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

  GPIO_Init(GPIOB, &GPIO_InitStructure);

  /* Time base configuration */

  TIM_TimeBaseStructure.TIM_Period = 7200;

  TIM_TimeBaseStructure.TIM_Prescaler = 0;

  TIM_TimeBaseStructure.TIM_ClockDivision = 0;

  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

  TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;

  TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Timing;

  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

  TIM_OCInitStructure.TIM_Pulse = 2000;

  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

  TIM_OC3Init(TIM3, &TIM_OCInitStructure);

  TIM_OC4Init(TIM3, &TIM_OCInitStructure);

  TIM_CCPreloadControl(TIM3, DISABLE);

  TIM_Cmd(TIM3, ENABLE);

  TIM_CtrlPWMOutputs(TIM3, ENABLE);

}

void run_motor(void){

    TIM_SelectOCxM(TIM3, TIM_Channel_3, TIM_OCMode_PWM1);

    TIM_CCxCmd(TIM3, TIM_Channel_3, TIM_CCx_Enable);

    TIM_SelectOCxM(TIM3, TIM_Channel_4, TIM_ForcedAction_Active);

    TIM_CCxCmd(TIM3, TIM_Channel_4, TIM_CCx_Disable);

}

with above code I get logic ''1'' at TIM3_CH3

instead of PWM

can anybody help ?

[Nickname13136_O]

Posted on July 05, 2011 at 08:16

Hello,

I hope you have enabled tim3 and GPIOB peripheral clock?

Rgds,

[mehmet.karakaya]

Posted on July 05, 2011 at 09:29

yes I have enabled them ;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

[mehmet.karakaya]

Posted on July 05, 2011 at 16:49

I am sorry

I found my coding error

the problem is solved

thank you

[Nickname13136_O]

Posted on July 08, 2011 at 10:33

It is great!