STM32F0xx_StdPeriph_Examples/TIM/TIM_EncoderMode/main.c

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/**
  ******************************************************************************
  * @file    TIM/TIM_EncoderMode/main.c  
  * @author  MCD Application Team
  * @version V1.4.0
  * @date    24-July-2014
  * @brief   Main program body
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT 2014 STMicroelectronics</center></h2>
  *
  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
  * You may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *        http://www.st.com/software_license_agreement_liberty_v2
  *
  * Unless required by applicable law or agreed to in writing, software 
  * distributed under the License is distributed on an "AS IS" BASIS, 
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  ******************************************************************************
  */

/* Includes ------------------------------------------------------------------*/
#include "main.h"

/** @addtogroup STM32F0xx_StdPeriph_Examples
  * @{
  */

/** @addtogroup TIM_EncoderMode
  * @{
  */

/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
uint16_t PrescalerValue = 0;

/* Private function prototypes -----------------------------------------------*/
static void TIM_Config(void);

/* Private functions ---------------------------------------------------------*/

/**
  * @brief  Main program.
  * @param  None
  * @retval None
  */
int main(void)
{
  /*!< At this stage the microcontroller clock setting is already configured, 
       this is done through SystemInit() function which is called from startup
       file (startup_stm32f0xx.s) before to branch to application main.
       To reconfigure the default setting of SystemInit() function, refer to
       system_stm32f0xx.c file
     */ 

  /* TIM Configuration */
  TIM_Config();
  
  /* Infinite loop */
  while (1)
  {
  }
}

/**
  * @brief  Configure the TIM pins and the TIM IRQ Handler.
  * @param  None
  * @retval None
  */
static void TIM_Config(void)
{
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
  NVIC_InitTypeDef NVIC_InitStructure;
  GPIO_InitTypeDef GPIO_InitStructure;

  /* TIM3 clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

  /* GPIOA clock enable */
  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
  
  /* TIM1 channel 2 pin (PE.11) configuration */
  GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_6 | 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_NOPULL;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

  /* Connect TIM pins to AF1 */
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_1);
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_1);
  
  /* -----------------------------------------------------------------------
    TIM3 Configuration: Encoder mode1:
    
    In this example TIM3 input clock (TIM3CLK) is set to APB1 clock (PCLK1).
      TIM3CLK = PCLK1  
      PCLK1 = HCLK
      => TIM3CLK = HCLK = SystemCoreClock
          
    To get TIM3 counter clock at 6 MHz, the prescaler is computed as follows:
       Prescaler = (TIM3CLK / TIM3 counter clock) - 1
       Prescaler = ((SystemCoreClock) /6 MHz) - 1

   TIM3 is configured to interface with an encoder:
   - The encoder mode is encoder mode1: Counter counts up/down on TI2 rising edge 
   depending on TI1 level 

   - The Autoreload value is set to 399, so the encoder round is 400 TIM counter clock.  
                                              

    Note: 
     SystemCoreClock variable holds HCLK frequency and is defined in system_stm32f0xx.c file.
     Each time the core clock (HCLK) changes, user had to call SystemCoreClockUpdate()
     function to update SystemCoreClock variable value. Otherwise, any configuration
     based on this variable will be incorrect.    
  ----------------------------------------------------------------------- */   


  /* Compute the prescaler value */
  PrescalerValue = (uint16_t) ((SystemCoreClock ) / 6000000) - 1;

  /* Time base configuration */
  TIM_TimeBaseStructure.TIM_Period = 399;
  TIM_TimeBaseStructure.TIM_Prescaler = 0;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

  TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

  /* Prescaler configuration */
  TIM_PrescalerConfig(TIM3, PrescalerValue, TIM_PSCReloadMode_Immediate);

  TIM_EncoderInterfaceConfig(TIM3, TIM_EncoderMode_TI1, TIM_ICPolarity_Rising, TIM_ICPolarity_Rising);
   
  /* TIM Interrupts enable */
  TIM_ITConfig(TIM3, TIM_IT_Update, ENABLE);

  /* TIM3 enable counter */
  TIM_Cmd(TIM3, ENABLE);
  
  /* Enable the TIM3 gloabal Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);
}

#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 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

/**
  * @}
  */

/**
  * @}
  */

/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/