STM CircleOS forum / timer 2 cc isr triggered twice! why?

kounst · 2009-09-01 15:28:55

Hi

I'm trying to measure the pwm signal of an rc receiver using cc2 of tim2.

The isr is triggered at each rising edge of the signal but also 2usec later - which I can't figure out why.

Thanks for any help!

Code:

/*******************************************************************************
* Function Name  : main
* Description    : Main program
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
int main(void)
{
#ifdef DEBUG
  debug();
#endif

  /* System clocks configuration ---------------------------------------------*/
  RCC_Configuration();

  /* NVIC configuration ------------------------------------------------------*/
  NVIC_Configuration();

  
    /* GPIO configuration */
    GPIO_Configuration();
   

    /* TIM2 Configuration */
    TIM2_Configuration();

  while (1)
  {
  }
}

/*******************************************************************************
* Function Name  : GPIO_Configuration
* Description    : Configure the used I/O ports pin
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
void GPIO_Configuration()
{
  GPIO_InitTypeDef  GPIO_InitStructure; 

  /* Configure capture compare input for pwm measurement */
  /* TIM2 channel 2 pin (PA.01) configuration */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
  
  /* Toggle Pin */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
}

/*******************************************************************************
* Function Name  : TIM2_Confgureation()
* Description    : 
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
void TIM2_Configuration(void)
{
  TIM_ICInitTypeDef  TIM_ICInitStructure;
  //TIM_ICInitStructure.TIM_ICMode = TIM_ICMode_ICAP;
  TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;
  TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;
  TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
  TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
  TIM_ICInitStructure.TIM_ICFilter = 0x0;
  TIM_ICInit(TIM2, &TIM_ICInitStructure);
  TIM_SelectInputTrigger(TIM2, TIM_TS_TI2FP2);

  TIM_InternalClockConfig(TIM2);
  TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
  TIM_TimeBaseStructure.TIM_Period = 0xFFFF;
  TIM_TimeBaseStructure.TIM_Prescaler = 72; 
  TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM2, & TIM_TimeBaseStructure);
  
  /* TIM enable counter */
  TIM_Cmd(TIM2, ENABLE);

  /* Enable the CC2 Interrupt Request */
  TIM_ITConfig(TIM2, TIM_IT_CC2, ENABLE);
}


/*******************************************************************************
* Function Name  : RCC_Configuration
* Description    : Configures the different system clocks.
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_Configuration(void)
{
  /* RCC system reset(for debug purpose) */
  RCC_DeInit();

  /* Enable HSE */
  RCC_HSEConfig(RCC_HSE_ON);

  /* Wait till HSE is ready */
  HSEStartUpStatus = RCC_WaitForHSEStartUp();

  if(HSEStartUpStatus == SUCCESS)
  {
    /* Enable Prefetch Buffer */
    FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);

    /* Flash 2 wait state */
    FLASH_SetLatency(FLASH_Latency_2);
 
    /* HCLK = SYSCLK */
    RCC_HCLKConfig(RCC_SYSCLK_Div1); 
  
    /* PCLK2 = HCLK */
    RCC_PCLK2Config(RCC_HCLK_Div1); 

    /* PCLK1 = HCLK/2 */
    RCC_PCLK1Config(RCC_HCLK_Div2);
 
    /* PLLCLK = 8MHz * 9 = 72 MHz */
    RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);

    /* Enable PLL */ 
    RCC_PLLCmd(ENABLE);

    /* Wait till PLL is ready */
    while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)
    {
    }

    /* Select PLL as system clock source */
    RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);

    /* Wait till PLL is used as system clock source */
    while(RCC_GetSYSCLKSource() != 0x08)
    {
    }
  }

/* Enable peripheral clocks --------------------------------------------------*/
  /* GPIOB Periph clock enable */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

  /* TIM2 clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

}

/*******************************************************************************
* Function Name  : NVIC_Configuration
* Description    : Configures Vector Table base location.
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
void NVIC_Configuration(void)
{
  NVIC_InitTypeDef NVIC_InitStructure;
#ifdef  VECT_TAB_RAM  
  /* Set the Vector Table base location at 0x20000000 */ 
  NVIC_SetVectorTable(NVIC_VectTab_RAM, 0x0); 
#else  /* VECT_TAB_FLASH  */
  /* Set the Vector Table base location at 0x08000000 */ 
  NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x0);   
#endif  

  /* Enable the TIM2 global Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQChannel;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);
}

#ifdef  DEBUG
/*******************************************************************************
* Function Name  : assert_failed
* Description    : Reports the name of the source file and the source line number
*                  where the assert_param error has occurred.
* Input          : - file: pointer to the source file name
*                  - line: assert_param error line source number
* Output         : None
* Return         : None
*******************************************************************************/
void assert_failed(u8* file, u32 line)
{ 
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */

  /* Infinite loop */
  while (1)
  {
  }
}
#endif

satishgn · 2009-09-01 19:40:40

Are you using PRIMER2 ?
If so then you need to update the following code
/* PLLCLK = 8MHz * 9 = 72 MHz */
RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);

To

/* PLLCLK = 12MHz * 6 = 72 MHz */
RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_6);

Since Primer2 uses a 12MHz X'tal.

Last edited by satishgn (2009-09-01 19:41:50)

kounst · 2009-09-01 20:16:26

Yes I'm using Primer2

I corrected the PLL configuration but it didn't solve the problem - I didn't expect it to. Thanks anyways!

I'm still stuck with the same problem. I'm absolutely sure that the input signal is accurate - so it has to be a problem with my program.

Thanks in advance,

kounst

kounst · 2009-09-02 15:17:07

Hello,

I have no idea why but now everything works just fine.

I did some minor changes to the code but those can't possibly affect the issue described above.

Regards,
kounst

# 1 2009-09-01 15:28:55 timer 2 cc isr triggered twice! why?

timer 2 cc isr triggered twice! why?

Code:

# 2 2009-09-01 19:40:40 timer 2 cc isr triggered twice! why?

Re: timer 2 cc isr triggered twice! why?

# 3 2009-09-01 20:16:26 timer 2 cc isr triggered twice! why?

Re: timer 2 cc isr triggered twice! why?

# 4 2009-09-02 15:17:07 timer 2 cc isr triggered twice! why?

Re: timer 2 cc isr triggered twice! why?

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