Input Capture: Channels and Capture Compare Register

[kzawada]

Posted on July 01, 2010 at 17:38

Input Capture: Channels and Capture Compare Register

[kzawada]

Posted on May 17, 2011 at 13:56

I see exactly what you are talking about in Figure 100.  This basically means that there is a 'daisy chain' of configuration that has to be made in order to capture the transitions on TIM4_CH4.  It is the following:

(1) TIM4_CH3

(2) TI3

(3) Input Filter/Edge Detector

(4) IC3

(5) Prescalar

(6) IC3PS

(7) Capture/Compare 4 Register

The configuration for making IC3 = TI3 is set by ''TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;''.

For some reason when I configure TIM4_CH3 (TI3) to be selected as IC3 I cannot get my firmware to generate an interrupt and call ''TIM4_IRQHandler()''.  I am using Keil RL-RTX and the library provided by Keil in ''C:\Keil\ARM\RV31\LIB\ST\STM32F10x'', where the NVIC is configured for TIM4_IRQChannel (=0x1F in Keil Library).

Is there anyway to troubleshoot why timer 4 is not generating an interrupt that calls the TIM4_IRQHandler() function?

The code modification that I have made is the following:

void InitializeInputCapture(void)

{

    TIM_ICInitTypeDef  TIM_ICInitStructure;

    GPIO_InitTypeDef GPIO_InitStructure;

    NVIC_InitTypeDef NVIC_InitStructure;

    // RCC Configuration -------------------------------------------------------

    // TIM3 clock enable

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);

   

    // GPIOA and GPIOB clock enable

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

    // Configure the Nested Interrupt Vector -----------------------------------

    // Enable the TIM3 global Interrupt

    NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQChannel;

    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;

    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;

    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

    NVIC_Init(&NVIC_InitStructure);

    // Input Capture Pin Configuration -----------------------------------------

    GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_8;

    //GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;

    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

    GPIO_Init(GPIOB, &GPIO_InitStructure);

    // Input Capture Configuration ---------------------------------------------

    TIM_ICInitStructure.TIM_Channel = TIM_Channel_3;

    TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;

    TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;

    TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV8;

    TIM_ICInitStructure.TIM_ICFilter = 0x0;

   

    TIM_ICInit(TIM4, &TIM_ICInitStructure);

   

    // TIM enable counter

    TIM_Cmd(TIM4, ENABLE);

   

    // Enable the CC2 Interrupt Request

    TIM_ITConfig(TIM4, TIM_IT_CC3, ENABLE);

}

[raptorhal2]

Posted on May 17, 2011 at 13:56

Look at Figure 100, All Densities Reference Manual RM008, Rev 10 to see the relationship between channels and capture compare registers.

Cheers, Hal

[kzawada]

Posted on May 17, 2011 at 13:56

The corresponding configuration is the following: