main.c

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/**
  ******************************************************************************
  * @file    TIM_Time_Base/main.c 
  * @author  MCD Application Team
  * @version V1.0.0
  * @date    23-March-2012
  * @brief   Main program body
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT 2012 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 "stm32f0xx.h"
#include "stm32f0_discovery.h"

/** @addtogroup STM32F0_Discovery_Peripheral_Examples
  * @{
  */

/** @addtogroup TIM_Time_Base
  * @{
  */

/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
__IO uint16_t CCR3_Val = 13654;
__IO uint16_t CCR4_Val = 6826;
uint16_t PrescalerValue = 0;
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
TIM_OCInitTypeDef  TIM_OCInitStructure;
/* Private function prototypes -----------------------------------------------*/
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();
  
  /* -----------------------------------------------------------------------
    TIM3 Configuration: Output Compare Timing Mode:
    
    In this example TIM3 input clock (TIM3CLK) is set to APB1 clock (PCLK1),  
      => TIM3CLK = PCLK1 = SystemCoreClock = 48 MHz
          
    To get TIM3 counter clock at 6 MHz, the prescaler is computed as follows:
       Prescaler = (TIM3CLK / TIM3 counter clock) - 1
       Prescaler = (PCLK1 /6 MHz) - 1
                                                  
    CC3 update rate = TIM3 counter clock / CCR3_Val = 439.4 Hz
    ==> Toggling frequency = 219.7 Hz
    
    CC4 update rate = TIM3 counter clock / CCR4_Val = 878.9 Hz
    ==> Toggling frequency = 439.4 Hz

    Note: 
     SystemCoreClock variable holds HCLK frequency and is defined in system_stm32f2xx.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 = 65535;
  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);

  /* Output Compare Timing Mode configuration: Channel1 */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Timing;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

  /* Output Compare Timing Mode configuration: Channel3 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = CCR3_Val;

  TIM_OC3Init(TIM3, &TIM_OCInitStructure);

  TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Disable);

  /* Output Compare Timing Mode configuration: Channel4 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = CCR4_Val;

  TIM_OC4Init(TIM3, &TIM_OCInitStructure);

  TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Disable);
   
  /* TIM Interrupts enable */
  TIM_ITConfig(TIM3, TIM_IT_CC3 | TIM_IT_CC4, ENABLE);

  /* TIM3 enable counter */
  TIM_Cmd(TIM3, ENABLE);

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

/**
  * @brief  Configure the TIM IRQ Handler.
  * @param  None
  * @retval None
  */
void TIM_Config(void)
{
  NVIC_InitTypeDef NVIC_InitStructure;

  /* TIM3 clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_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);

  /* Initialize Leds mounted on STM32F0-Discovery */
  STM_EVAL_LEDInit(LED3);
  STM_EVAL_LEDInit(LED4);

  /* Turn on LED3 and LED4 */
  STM_EVAL_LEDOn(LED3);
  STM_EVAL_LEDOn(LED4);
}

#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****/