STM8S_StdPeriph_Examples/IWDG/IWDG_Example/main.c

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/**
  ******************************************************************************
  * @file    IWDG_Example\main.c
  * @author  MCD Application Team
  * @version  V2.2.0
  * @date     30-September-2014
  * @brief   This file contains the main function for IWDG Reset example.
  ******************************************************************************
  * @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 "stm8s.h"
#include "stm8s_eval.h"

/**
  * @addtogroup IWDG_Example
  * @{
  */

/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
__IO uint32_t LsiFreq = 0;
/* Private function prototypes -----------------------------------------------*/
static void CLK_Config(void);
static void GPIO_Config(void);
static void IWDG_Config(void);
static uint32_t LSIMeasurment(void);
/* Private functions ---------------------------------------------------------*/

/**
  * @brief  Main program.
  * @param  None
  * @retval None
  */
void main(void)
{
  /* Clock Configuration */
  CLK_Config(); 
      
  /* GPIO Configuration */
  GPIO_Config();

  /* Check if the system has resumed from IWDG reset */
  if (RST_GetFlagStatus(RST_FLAG_IWDGF) != RESET)
  {
    /* IWDGF flag set */
    /* Turn on LED1 */
    STM_EVAL_LEDOn(LED1);

    /* Clear IWDGF Flag */
    RST_ClearFlag(RST_FLAG_IWDGF);
  }
  else
  {
    /* IWDGF flag is not set */
    /* Turn off LED1 */
    STM_EVAL_LEDOff(LED1);
  }

  /* Get measured LSI frequency */
  LsiFreq = LSIMeasurment();  
  
  /* IWDG Configuration */
  IWDG_Config();
  
  while (1)
  {
    /* Reload IWDG counter */
    IWDG_ReloadCounter();  
  }
}

/**
  * @brief  Configure system clock to run at 16Mhz
  * @param  None
  * @retval None
  */
static void CLK_Config(void)
{
  /* Initialization of the clock */
  /* Clock divider to HSI/1 */
  CLK_HSIPrescalerConfig(CLK_PRESCALER_HSIDIV1);
}

/**
  * @brief  Configures the IWDG to generate a Reset if it is not refreshed at the
  *         correct time. 
  * @param  None
  * @retval None
  */
static void IWDG_Config(void)
{
  /* Enable IWDG (the LSI oscillator will be enabled by hardware) */
  IWDG_Enable();
  
  /* IWDG timeout equal to 250 ms (the timeout may varies due to LSI frequency
     dispersion) */
  /* Enable write access to IWDG_PR and IWDG_RLR registers */
  IWDG_WriteAccessCmd(IWDG_WriteAccess_Enable);
  
  /* IWDG counter clock: LSI/128 */
  IWDG_SetPrescaler(IWDG_Prescaler_128);
  
  /* Set counter reload value to obtain 250ms IWDG TimeOut.
    Counter Reload Value = 250ms/IWDG counter clock period
                         = 250ms / (LSI/128)
                         = 0.25s / (LsiFreq/128)
                         = LsiFreq/(128 * 4)
                         = LsiFreq/512
   */
  IWDG_SetReload((uint8_t)(LsiFreq/512));
  
  /* Reload IWDG counter */
  IWDG_ReloadCounter();
}

/**
  * @brief  Initialize LED1 and Key Button mounted on the evaluation board
  * @param  None
  * @retval None
  */
static void GPIO_Config(void) 
{
  /* Configure LED1 */
  STM_EVAL_LEDInit(LED1);
  STM_EVAL_LEDOff(LED1);

  /* Configure Key button */
  STM_EVAL_PBInit(BUTTON_KEY, BUTTON_MODE_EXTI);
  
  /* enable interrupts */
  enableInterrupts();
}

/**
  * @brief  Measure the LSI frequency using timer IC1 and update the calibration registers.
  * @note   It is recommended to use a timer clock frequency of at least 10MHz in order 
  *         to obtain a better in the LSI frequency measurement.
  * @param  None
  * @retval None
  */
static uint32_t LSIMeasurment(void)
{
  uint32_t lsi_freq_hz = 0x0;
  uint32_t fmaster = 0x0;
  uint16_t ICValue1 = 0x0;
  uint16_t ICValue2 = 0x0;

  /* Get master frequency */
  fmaster = CLK_GetClockFreq();

  /* Enable the LSI measurement: LSI clock connected to timer Input Capture 1 */
  AWU->CSR |= AWU_CSR_MSR;

#if defined (STM8S903) || defined (STM8S103) || defined (STM8S003)
  /* Measure the LSI frequency with TIMER Input Capture 1 */
  
  /* Capture only every 8 events!!! */
  /* Enable capture of TI1 */
  TIM1_ICInit(TIM1_CHANNEL_1, TIM1_ICPOLARITY_RISING, TIM1_ICSELECTION_DIRECTTI,
              TIM1_ICPSC_DIV8, 0);
  
  /* Enable TIM1 */
  TIM1_Cmd(ENABLE);
  
  /* wait a capture on cc1 */
  while((TIM1->SR1 & TIM1_FLAG_CC1) != TIM1_FLAG_CC1);
  /* Get CCR1 value*/
  ICValue1 = TIM1_GetCapture1();
  TIM1_ClearFlag(TIM1_FLAG_CC1);
  
  /* wait a capture on cc1 */
  while((TIM1->SR1 & TIM1_FLAG_CC1) != TIM1_FLAG_CC1);
  /* Get CCR1 value*/
  ICValue2 = TIM1_GetCapture1();
  TIM1_ClearFlag(TIM1_FLAG_CC1);
  
  /* Disable IC1 input capture */
  TIM1->CCER1 &= (uint8_t)(~TIM1_CCER1_CC1E);
  /* Disable timer2 */
  TIM1_Cmd(DISABLE);
  
#else  
  /* Measure the LSI frequency with TIMER Input Capture 1 */
  
  /* Capture only every 8 events!!! */
  /* Enable capture of TI1 */
  TIM3_ICInit(TIM3_CHANNEL_1, TIM3_ICPOLARITY_RISING, TIM3_ICSELECTION_DIRECTTI,
              TIM3_ICPSC_DIV8, 0);

  /* Enable TIM3 */
  TIM3_Cmd(ENABLE);

  /* wait a capture on cc1 */
  while ((TIM3->SR1 & TIM3_FLAG_CC1) != TIM3_FLAG_CC1);
  /* Get CCR1 value*/
  ICValue1 = TIM3_GetCapture1();
  TIM3_ClearFlag(TIM3_FLAG_CC1);

  /* wait a capture on cc1 */
  while ((TIM3->SR1 & TIM3_FLAG_CC1) != TIM3_FLAG_CC1);
    /* Get CCR1 value*/
  ICValue2 = TIM3_GetCapture1();
  TIM3_ClearFlag(TIM3_FLAG_CC1);

  /* Disable IC1 input capture */
  TIM3->CCER1 &= (uint8_t)(~TIM3_CCER1_CC1E);
  /* Disable timer3 */
  TIM3_Cmd(DISABLE);
#endif

  /* Compute LSI clock frequency */
  lsi_freq_hz = (8 * fmaster) / (ICValue2 - ICValue1);
  
  /* Disable the LSI measurement: LSI clock disconnected from timer Input Capture 1 */
  AWU->CSR &= (uint8_t)(~AWU_CSR_MSR);

 return (lsi_freq_hz);
}

#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

/**
  * @}
  */


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