STM32F0xx_StdPeriph_Examples/TIM/TIM_SynchronizationMode/main.c

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/**
  ******************************************************************************
  * @file    TIM/TIM_SynchronizationMode/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_SynchronizationMode
  * @{
  */

/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
/* 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
     */ 

  /* TIM2/3 Configuration */
  TIM_Config();

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

/**
  * @brief  Configure the TIM2/3 Pins.
  * @param  None
  * @retval None
  */
static void TIM_Config(void)
{
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
  TIM_OCInitTypeDef  TIM_OCInitStructure;
  GPIO_InitTypeDef GPIO_InitStructure;

  /* TIM2 and TIM3 clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2 | RCC_APB1Periph_TIM3 , ENABLE);

  /* GPIOA and GPIOB clocks enable */
  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA | RCC_AHBPeriph_GPIOB, ENABLE);

  /* GPIOB Configuration: PB4(TIM3 CH1) as alternate function push-pull ------*/
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;
  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(GPIOB, &GPIO_InitStructure);

  /* Connect TIM pins to AF1 */
  GPIO_PinAFConfig(GPIOB, GPIO_PinSource4, GPIO_AF_1);

  /* GPIOA Configuration: PA5(TIM2 CH1) as alternate function push-pull ------*/
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

  /* Connect TIM pins to AF2 */
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_2);

  /* Timers synchronisation in cascade mode ----------------------------
     1/TIM2 is configured as Master Timer:
         - PWM Mode is used
         - The TIM2 Update event is used as Trigger Output  

     2/TIM3 is slave for TIM2,
         - PWM Mode is used
         - The ITR1(TIM2) is used as input trigger 
         - Gated mode is used, so start and stop of slave counter are controlled
           by the Master trigger output signal(TIM2 update event).

     In this example TIM2 input clock (TIM2CLK) is set to APB1 clock (PCLK1).   
       TIM2CLK = PCLK1  
       PCLK1 = HCLK 
       => TIM2CLK = HCLK = SystemCoreClock = 48 MHz

     The TIM2 is running at:
         TIM2 frequency = (TIM2 counter clock)/ (TIM2 period + 1) = 187.5 KHz 
     and duty cycle = TIM2_CCR1/(TIM2_ARR + 1) = 25%.

     The slave Timer TIM3 is running at TIM2 clock:
         (TIM2 frequency)/ (TIM3 period + 1) = 46.87 KHz
     and duty cycle equal = TIM3_CCR1/(TIM3_ARR + 1) = 25%
  
       The Master Timer TIM2 is running at TIM2 counter clock:
       TIM2 frequency = (TIM2 counter clock)/ (TIM2 period + 1) = 187.5 KHz 
       and the duty cycle = TIM2_CCR1/(TIM2_ARR + 1) = 25%.

 
     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. 
  --------------------------------------------------------------------------- */

  /* Time base configuration */
  TIM_TimeBaseStructure.TIM_Period = 255;
  TIM_TimeBaseStructure.TIM_Prescaler = 0;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

  TIM_TimeBaseStructure.TIM_Period = 3;
  TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

  /* Master Configuration in PWM1 Mode */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 64;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

  TIM_OC1Init(TIM2, &TIM_OCInitStructure);

  /* Select the Master Slave Mode */
  TIM_SelectMasterSlaveMode(TIM2, TIM_MasterSlaveMode_Enable);

  /* Master Mode selection */
  TIM_SelectOutputTrigger(TIM2, TIM_TRGOSource_Update);

  /* Slaves Configuration: PWM1 Mode */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 1;

  TIM_OC1Init(TIM3, &TIM_OCInitStructure);

  /* Slave Mode selection: TIM3 */
  TIM_SelectSlaveMode(TIM3, TIM_SlaveMode_Gated);
  TIM_SelectInputTrigger(TIM3, TIM_TS_ITR1);
 
  /* TIM enable counter */
  TIM_Cmd(TIM3, ENABLE);
  TIM_Cmd(TIM2, ENABLE);

}

#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****/