stm32l1xx_rcc.c

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  4. To further reduce power consumption in SLEEP mode the peripheral clocks can
     be disabled prior to executing the WFI or WFE instructions. You can do this
     using RCC_AHBPeriphClockLPModeCmd(), RCC_APB2PeriphClockLPModeCmd() and
     RCC_APB1PeriphClockLPModeCmd() functions.  

@endverbatim
  * @{
  */

/**
  * @brief  Configures the RTC and LCD clock (RTCCLK / LCDCLK).
  * @note   - As the RTC clock configuration bits are in the RTC domain and write
  *           access is denied to this domain after reset, you have to enable write
  *           access using PWR_RTCAccessCmd(ENABLE) function before to configure
  *           the RTC clock source (to be done once after reset).    
  *         - Once the RTC clock is configured it can't be changed unless the RTC
  *           is reset using RCC_RTCResetCmd function, or by a Power On Reset (POR)
  *         - The RTC clock (RTCCLK) is used also to clock the LCD (LCDCLK).
  *             
  * @param  RCC_RTCCLKSource: specifies the RTC clock source.
  *   This parameter can be one of the following values:
  *     @arg RCC_RTCCLKSource_LSE: LSE selected as RTC clock
  *     @arg RCC_RTCCLKSource_LSI: LSI selected as RTC clock
  *     @arg RCC_RTCCLKSource_HSE_Div2: HSE divided by 2 selected as RTC clock
  *     @arg RCC_RTCCLKSource_HSE_Div4: HSE divided by 4 selected as RTC clock
  *     @arg RCC_RTCCLKSource_HSE_Div8: HSE divided by 8 selected as RTC clock
  *     @arg RCC_RTCCLKSource_HSE_Div16: HSE divided by 16 selected as RTC clock
  *       
  * @note   - If the LSE or LSI is used as RTC clock source, the RTC continues to
  *           work in STOP and STANDBY modes, and can be used as wakeup source.
  *           However, when the HSE clock is used as RTC clock source, the RTC
  *           cannot be used in STOP and STANDBY modes.
  *             
  *         - The maximum input clock frequency for RTC is 1MHz (when using HSE as
  *           RTC clock source).
  *                          
  * @retval None
  */
void RCC_RTCCLKConfig(uint32_t RCC_RTCCLKSource)
{
  uint32_t 	tmpreg = 0;

  /* Check the parameters */
  assert_param(IS_RCC_RTCCLK_SOURCE(RCC_RTCCLKSource));
  
  if ((RCC_RTCCLKSource & RCC_CSR_RTCSEL_HSE) == RCC_CSR_RTCSEL_HSE)
  { 
    /* If HSE is selected as RTC clock source, configure HSE division factor for RTC clock */
    tmpreg = RCC->CR;

    /* Clear RTCPRE[1:0] bits */
    tmpreg &= ~RCC_CR_RTCPRE;

    /* Configure HSE division factor for RTC clock */
    tmpreg |= (RCC_RTCCLKSource & RCC_CR_RTCPRE);

    /* Store the new value */
    RCC->CR = tmpreg;
  }
         
  RCC->CSR &= ~RCC_CSR_RTCSEL;
  
  /* Select the RTC clock source */
  RCC->CSR |= (RCC_RTCCLKSource & RCC_CSR_RTCSEL);
}

/**
  * @brief  Enables or disables the RTC clock.
  * @note   This function must be used only after the RTC clock source was selected
  *         using the RCC_RTCCLKConfig function.
  * @param  NewState: new state of the RTC clock.
  *   This parameter can be: ENABLE or DISABLE.
  * @retval None
  */
void RCC_RTCCLKCmd(FunctionalState NewState)
{
  /* Check the parameters */
  assert_param(IS_FUNCTIONAL_STATE(NewState));
  
  *(__IO uint32_t *) CSR_RTCEN_BB = (uint32_t)NewState;
}

/**
  * @brief  Forces or releases the RTC peripheral and associated resources reset.
  * @note   This function resets the RTC peripheral, RTC clock source selection
  *         (in RCC_CSR) and the backup registers.
  * @param  NewState: new state of the RTC reset.
  *   This parameter can be: ENABLE or DISABLE.
  * @retval None
  */
void RCC_RTCResetCmd(FunctionalState NewState)
{
  /* Check the parameters */
  assert_param(IS_FUNCTIONAL_STATE(NewState));
  
  *(__IO uint32_t *) CSR_RTCRST_BB = (uint32_t)NewState;
}

/**
  * @brief  Enables or disables the AHB peripheral clock.
  * @note   After reset, the peripheral clock (used for registers read/write access)
  *         is disabled and the application software has to enable this clock before 
  *         using it.    
  * @param  RCC_AHBPeriph: specifies the AHB peripheral to gates its clock.
  *   This parameter can be any combination of the following values:
  *     @arg RCC_AHBPeriph_GPIOA
  *     @arg RCC_AHBPeriph_GPIOB
  *     @arg RCC_AHBPeriph_GPIOC  
  *     @arg RCC_AHBPeriph_GPIOD
  *     @arg RCC_AHBPeriph_GPIOE
  *     @arg RCC_AHBPeriph_GPIOH
  *     @arg RCC_AHBPeriph_CRC
  *     @arg RCC_AHBPeriph_FLITF (has effect only when the Flash memory is in power down mode)  
  *     @arg RCC_AHBPeriph_DMA1
  * @param  NewState: new state of the specified peripheral clock.
  *         This parameter can be: ENABLE or DISABLE.
  * @retval None
  */
void RCC_AHBPeriphClockCmd(uint32_t RCC_AHBPeriph, FunctionalState NewState)
{
  /* Check the parameters */
  assert_param(IS_RCC_AHB_PERIPH(RCC_AHBPeriph));
  assert_param(IS_FUNCTIONAL_STATE(NewState));
  
  if (NewState != DISABLE)
  {
    RCC->AHBENR |= RCC_AHBPeriph;
  }
  else
  {
    RCC->AHBENR &= ~RCC_AHBPeriph;
  }
}

/**
  * @brief  Enables or disables the High Speed APB (APB2) peripheral clock.
  * @note   After reset, the peripheral clock (used for registers read/write access)
  *         is disabled and the application software has to enable this clock before 
  *         using it.
  * @param  RCC_APB2Periph: specifies the APB2 peripheral to gates its clock.
  *   This parameter can be any combination of the following values:
  *     @arg RCC_APB2Periph_SYSCFG
  *     @arg RCC_APB2Periph_TIM9
  *     @arg RCC_APB2Periph_TIM10
  *     @arg RCC_APB2Periph_TIM11
  *     @arg RCC_APB2Periph_ADC1
  *     @arg RCC_APB2Periph_SPI1
  *     @arg RCC_APB2Periph_USART1            
  * @param  NewState: new state of the specified peripheral clock.
  *         This parameter can be: ENABLE or DISABLE.
  * @retval None
  */
void RCC_APB2PeriphClockCmd(uint32_t RCC_APB2Periph, FunctionalState NewState)
{
  /* Check the parameters */
  assert_param(IS_RCC_APB2_PERIPH(RCC_APB2Periph));
  assert_param(IS_FUNCTIONAL_STATE(NewState));

  if (NewState != DISABLE)
  {
    RCC->APB2ENR |= RCC_APB2Periph;
  }
  else
  {
    RCC->APB2ENR &= ~RCC_APB2Periph;
  }
}

/**
  * @brief  Enables or disables the Low Speed APB (APB1) peripheral clock.
  * @note   After reset, the peripheral clock (used for registers read/write access)
  *         is disabled and the application software has to enable this clock before 
  *         using it.
  * @param  RCC_APB1Periph: specifies the APB1 peripheral to gates its clock.
  *   This parameter can be any combination of the following values:
  *     @arg RCC_APB1Periph_TIM2
  *     @arg RCC_APB1Periph_TIM3
  *     @arg RCC_APB1Periph_TIM4
  *     @arg RCC_APB1Periph_TIM6
  *     @arg RCC_APB1Periph_TIM7
  *     @arg RCC_APB1Periph_LCD
  *     @arg RCC_APB1Periph_WWDG
  *     @arg RCC_APB1Periph_SPI2
  *     @arg RCC_APB1Periph_USART2
  *     @arg RCC_APB1Periph_USART3
  *     @arg RCC_APB1Periph_I2C1
  *     @arg RCC_APB1Periph_I2C2
  *     @arg RCC_APB1Periph_USB
  *     @arg RCC_APB1Periph_PWR
  *     @arg RCC_APB1Periph_DAC
  *     @arg RCC_APB1Periph_COMP                                
  * @param  NewState: new state of the specified peripheral clock.
  *         This parameter can be: ENABLE or DISABLE.
  * @retval None
  */
void RCC_APB1PeriphClockCmd(uint32_t RCC_APB1Periph, FunctionalState NewState)
{
  /* Check the parameters */
  assert_param(IS_RCC_APB1_PERIPH(RCC_APB1Periph));
  assert_param(IS_FUNCTIONAL_STATE(NewState));

  if (NewState != DISABLE)
  {
    RCC->APB1ENR |= RCC_APB1Periph;
  }
  else
  {
    RCC->APB1ENR &= ~RCC_APB1Periph;
  }
}

/**
  * @brief  Forces or releases AHB peripheral reset.
  * @param  RCC_AHBPeriph: specifies the AHB peripheral to reset.
  *   This parameter can be any combination of the following values:
  *     @arg RCC_AHBPeriph_GPIOA
  *     @arg RCC_AHBPeriph_GPIOB
  *     @arg RCC_AHBPeriph_GPIOC  
  *     @arg RCC_AHBPeriph_GPIOD
  *     @arg RCC_AHBPeriph_GPIOE
  *     @arg RCC_AHBPeriph_GPIOH
  *     @arg RCC_AHBPeriph_CRC
  *     @arg RCC_AHBPeriph_FLITF (has effect only when the Flash memory is in power down mode)  
  *     @arg RCC_AHBPeriph_DMA1   
  * @param  NewState: new state of the specified peripheral reset.
  *         This parameter can be: ENABLE or DISABLE.
  * @retval None
  */
void RCC_AHBPeriphResetCmd(uint32_t RCC_AHBPeriph, FunctionalState NewState)
{
  /* Check the parameters */
  assert_param(IS_RCC_AHB_PERIPH(RCC_AHBPeriph));
  assert_param(IS_FUNCTIONAL_STATE(NewState));

  if (NewState != DISABLE)
  {
    RCC->AHBRSTR |= RCC_AHBPeriph;
  }
  else
  {
    RCC->AHBRSTR &= ~RCC_AHBPeriph;
  }
}

/**
  * @brief  Forces or releases High Speed APB (APB2) peripheral reset.
  * @param  RCC_APB2Periph: specifies the APB2 peripheral to reset.
  *   This parameter can be any combination of the following values:
  *     @arg RCC_APB2Periph_SYSCFG
  *     @arg RCC_APB2Periph_TIM9
  *     @arg RCC_APB2Periph_TIM10
  *     @arg RCC_APB2Periph_TIM11
  *     @arg RCC_APB2Periph_ADC1
  *     @arg RCC_APB2Periph_SPI1
  *     @arg RCC_APB2Periph_USART1  
  * @param  NewState: new state of the specified peripheral reset.
  *         This parameter can be: ENABLE or DISABLE.
  * @retval None
  */
void RCC_APB2PeriphResetCmd(uint32_t RCC_APB2Periph, FunctionalState NewState)
{
  /* Check the parameters */
  assert_param(IS_RCC_APB2_PERIPH(RCC_APB2Periph));
  assert_param(IS_FUNCTIONAL_STATE(NewState));

  if (NewState != DISABLE)
  {
    RCC->APB2RSTR |= RCC_APB2Periph;
  }
  else
  {
    RCC->APB2RSTR &= ~RCC_APB2Periph;
  }
}

/**
  * @brief  Forces or releases Low Speed APB (APB1) peripheral reset.
  * @param  RCC_APB1Periph: specifies the APB1 peripheral to reset.
  *   This parameter can be any combination of the following values:
  *     @arg RCC_APB1Periph_TIM2
  *     @arg RCC_APB1Periph_TIM3
  *     @arg RCC_APB1Periph_TIM4
  *     @arg RCC_APB1Periph_TIM6
  *     @arg RCC_APB1Periph_TIM7
  *     @arg RCC_APB1Periph_LCD
  *     @arg RCC_APB1Periph_WWDG
  *     @arg RCC_APB1Periph_SPI2
  *     @arg RCC_APB1Periph_USART2
  *     @arg RCC_APB1Periph_USART3
  *     @arg RCC_APB1Periph_I2C1
  *     @arg RCC_APB1Periph_I2C2
  *     @arg RCC_APB1Periph_USB
  *     @arg RCC_APB1Periph_PWR
  *     @arg RCC_APB1Periph_DAC
  *     @arg RCC_APB1Periph_COMP    
  * @param  NewState: new state of the specified peripheral clock.
  *         This parameter can be: ENABLE or DISABLE.
  * @retval None
  */
void RCC_APB1PeriphResetCmd(uint32_t RCC_APB1Periph, FunctionalState NewState)
{
  /* Check the parameters */
  assert_param(IS_RCC_APB1_PERIPH(RCC_APB1Periph));
  assert_param(IS_FUNCTIONAL_STATE(NewState));

  if (NewState != DISABLE)
  {
    RCC->APB1RSTR |= RCC_APB1Periph;
  }
  else
  {
    RCC->APB1RSTR &= ~RCC_APB1Periph;
  }
}