Wrong value of Duty Cycle value of PWM Input Capture

[nitin29]

Posted on July 28, 2016 at 18:23

Hi All,

I was trying to measure duty cycle and frequency of a pwm signal by using a timer with pwm output to generate pwm signal and another timer in reset mode to measure pwm using one of the example. The logic analyzer shows 97 % to 50 % for duty cycle and 14400 hz for frequency but the measured value using reset mode, the duty cycle is always 0 % and frequency comes out 14403 hz to 14405 hz. What is the mistake? Code is attached.

/**
******************************************************************************
* File Name : main.c
* Description : Main program body
******************************************************************************
*
* COPYRIGHT(c) 2016 STMicroelectronics
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. Neither the name of STMicroelectronics nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ''AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
******************************************************************************
*/
/* Includes ------------------------------------------------------------------*/
#include ''stm32f1xx_hal.h''
/* USER CODE BEGIN Includes */
/* USER CODE END Includes */
/* Private variables ---------------------------------------------------------*/
TIM_HandleTypeDef htim3;
TIM_HandleTypeDef htim4;
/* USER CODE BEGIN PV */
/* Private variables ---------------------------------------------------------*/
__IO float sigDuty = 0;
__IO uint32_t sigFreq = 0;
__IO uint32_t sigICRValue = 0;
__IO uint32_t errFlag = 0;
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_TIM4_Init(void);
static void MX_TIM3_Init(void);
void HAL_TIM_MspPostInit(TIM_HandleTypeDef *htim);
/* USER CODE BEGIN PFP */
/* Private function prototypes -----------------------------------------------*/
void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim);
/* USER CODE END PFP */
/* USER CODE BEGIN 0 */
/* USER CODE END 0 */
int main(void)
{
/* USER CODE BEGIN 1 */
/* USER CODE END 1 */
/* MCU Configuration----------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* Configure the system clock */
SystemClock_Config();
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_TIM4_Init();
MX_TIM3_Init();
/* USER CODE BEGIN 2 */
// timer 3
HAL_TIM_PWM_Start(&htim3,TIM_CHANNEL_4);
HAL_TIM_Base_Start(&htim3);
// timer 4
if(HAL_TIM_IC_Start_IT(&htim4, TIM_CHANNEL_2)!=HAL_OK)
errFlag = 1;
if(HAL_TIM_IC_Start_IT(&htim4, TIM_CHANNEL_1)!=HAL_OK)
errFlag = 2;
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}
/** System Clock Configuration
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct;
RCC_ClkInitTypeDef RCC_ClkInitStruct;
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
HAL_RCC_OscConfig(&RCC_OscInitStruct);
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2);
HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);
/* SysTick_IRQn interrupt configuration */
HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
}
/* TIM3 init function */
void MX_TIM3_Init(void)
{
TIM_MasterConfigTypeDef sMasterConfig;
TIM_OC_InitTypeDef sConfigOC;
htim3.Instance = TIM3;
htim3.Init.Prescaler = 499;
htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
htim3.Init.Period = 9;
htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
HAL_TIM_PWM_Init(&htim3);
sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
HAL_TIMEx_MasterConfigSynchronization(&htim3, &sMasterConfig);
sConfigOC.OCMode = TIM_OCMODE_PWM1;
sConfigOC.Pulse = 5;
sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
sConfigOC.OCFastMode = TIM_OCFAST_ENABLE;
HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_4);
HAL_TIM_MspPostInit(&htim3);
}
/* TIM4 init function */
void MX_TIM4_Init(void)
{
TIM_SlaveConfigTypeDef sSlaveConfig;
TIM_MasterConfigTypeDef sMasterConfig;
TIM_IC_InitTypeDef sConfigIC;
htim4.Instance = TIM4;
htim4.Init.Prescaler = 0;
htim4.Init.CounterMode = TIM_COUNTERMODE_UP;
htim4.Init.Period = 65535;
htim4.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
HAL_TIM_Base_Init(&htim4);
HAL_TIM_IC_Init(&htim4);
sSlaveConfig.SlaveMode = TIM_SLAVEMODE_RESET;
sSlaveConfig.InputTrigger = TIM_TS_TI2FP2;
sSlaveConfig.TriggerPolarity = TIM_TRIGGERPOLARITY_BOTHEDGE;
sSlaveConfig.TriggerFilter = 0;
HAL_TIM_SlaveConfigSynchronization(&htim4, &sSlaveConfig);
sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
HAL_TIMEx_MasterConfigSynchronization(&htim4, &sMasterConfig);
sConfigIC.ICPolarity = TIM_INPUTCHANNELPOLARITY_FALLING;
sConfigIC.ICSelection = TIM_ICSELECTION_INDIRECTTI;
sConfigIC.ICPrescaler = TIM_ICPSC_DIV1;
sConfigIC.ICFilter = 0;
HAL_TIM_IC_ConfigChannel(&htim4, &sConfigIC, TIM_CHANNEL_1);
sConfigIC.ICPolarity = TIM_INPUTCHANNELPOLARITY_RISING;
sConfigIC.ICSelection = TIM_ICSELECTION_DIRECTTI;
HAL_TIM_IC_ConfigChannel(&htim4, &sConfigIC, TIM_CHANNEL_2);
}
/** Configure pins as 
* Analog 
* Input 
* Output
* EVENT_OUT
* EXTI
*/
void MX_GPIO_Init(void)
{
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOD_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
}
/* USER CODE BEGIN 4 */
void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim)
{
if(htim->Channel == HAL_TIM_ACTIVE_CHANNEL_2)
{
sigICRValue = HAL_TIM_ReadCapturedValue(htim, TIM_CHANNEL_2);
if(sigICRValue != 0)
{
sigDuty = ((HAL_TIM_ReadCapturedValue(htim, TIM_CHANNEL_1))* 100 ) / sigICRValue;
sigFreq = (HAL_RCC_GetHCLKFreq()) / sigICRValue;
}
else
{
sigDuty = 0;
sigFreq = 0;
}
}
else
{
errFlag = 3;
}
}
/* USER CODE END 4 */
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t* file, uint32_t line)
{
/* USER CODE BEGIN 6 */
/* 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) */
/* USER CODE END 6 */
}
#endif
/**
* @}
*/ 
/**
* @}
*/ 
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

#input-capture #pwm-input-capture

[nitin29]

Posted on July 28, 2016 at 18:42

Well, the solution was so basic. Sorry for this post, if possible Admin please delete this post. If not deleted, I just want to say how i fixed it. I just changed

sigDuty = ((HAL_TIM_ReadCapturedValue(htim, TIM_CHANNEL_1))* 100 ) / sigICRValue; to sigDuty = ((HAL_TIM_ReadCapturedValue(htim, TIM_CHANNEL_1))* 0 ) / (float)sigICRValue;