PWM input works on TIM2 Ch2 but not Ch3

[colinconstant]

Posted on March 14, 2015 at 11:40

Hi, I'm measuring the pulse width on one line, using TIM2. Everthing is fine if I use Ch2 (on PD4 or PB3) but I can't get a reading using Ch3 (on PD7).

I'm using : TIM_GetCapture1(TIM2) Here is the init code, thanks very much for any ideas.

  //RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOB, ENABLE); //PB3

  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOD, ENABLE);  //PD4 or PD7  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);   //enable the TIM2 clock    /* Pin configuration */   GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_7;      GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AF;   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;   GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;   GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP ;   //GPIO_Init(GPIOB, &GPIO_InitStructure);  //PB3  GPIO_Init(GPIOD, &GPIO_InitStructure);  //PD4 or PD7     //GPIO_PinAFConfig(GPIOB, GPIO_PinSource3, GPIO_AF_1); //PB3 and AF1   GPIO_PinAFConfig(GPIOD, GPIO_PinSource7, GPIO_AF_2); //PD7 and AF2    /* Input configuration */  //TIM_ICInitStructure.TIM_Channel = TIM_Channel_2; //PB3 or PD4  TIM_ICInitStructure.TIM_Channel = TIM_Channel_3;  //PD7   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_PWMIConfig(TIM2, &TIM_ICInitStructure);

 TIM_SelectInputTrigger(TIM2, TIM_TS_TI2FP2);

  TIM_SelectSlaveMode(TIM2, TIM_SlaveMode_Reset);   TIM_SelectMasterSlaveMode(TIM2,TIM_MasterSlaveMode_Enable);     TIM_Cmd(TIM2, ENABLE); //enable timer

[Tesla DeLorean]

Posted on March 14, 2015 at 14:33

PWM Input pairs channel 1 and 2, where TS_TI2FP2 selects channel 2.

Channel 3 and 4 are not options provided by the hardware. You'd have to use Input Capture and delta multiple measurements to compute period/duty.

[colinconstant]

Posted on March 14, 2015 at 16:40

Thank you Clive.

Colin