text: /**
    ******************************************************************************
    * @file    Examples_LL/USART/USART_HardwareFlowControl/Src/main.c
    * @author  MCD Application Team
    * @brief   This example describes how to transfer bytes from/to an USART peripheral 
    *          to/from a PC UART with HW FLow Control enabled, 
    *          through the STM32F7xx USART LL API.
    *          Peripheral initialization done using LL unitary services functions.
    ******************************************************************************
    * @attention
    *
    * <h2><center>&copy; COPYRIGHT(c) 2016 STMicroelectronics</center></h2>
    *
    * Redistribution and use in source and binary forms, with or without modification,
    * are permitted provided that the following conditions are met:
    *   1. Redistributions of source code must retain the above copyright notice,
    *      this list of conditions and the following disclaimer.
    *   2. Redistributions in binary form must reproduce the above copyright notice,
    *      this list of conditions and the following disclaimer in the documentation
    *      and/or other materials provided with the distribution.
    *   3. Neither the name of STMicroelectronics nor the names of its contributors
    *      may be used to endorse or promote products derived from this software
    *      without specific prior written permission.
    *
    * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
    * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
    * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
    * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
    * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
    * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
    * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    *
    ******************************************************************************
    */
  
  /* Includes ------------------------------------------------------------------*/
  #include "main.h"
  
  /** @addtogroup STM32F7xx_LL_Examples
    * @{
    */
  
  /** @addtogroup USART_HardwareFlowControl
    * @{
    */
  
  /* Private typedef -----------------------------------------------------------*/
  /* Private define ------------------------------------------------------------*/
  /* Private macro -------------------------------------------------------------*/
  
  /* Private variables ---------------------------------------------------------*/
  __IO uint8_t ubButtonPress = 0;
  
  /**
    * @brief Variables used for character tranmission to PC Com port
    */
  __IO uint8_t ubSend = 0;
  const uint8_t aStringToSend[] = "STM32F7xx USART LL API Example : TX/RX in IT mode\r\nConfiguration UART 115200 bps, 8 data bit/1 stop bit/No parity/HW flow control enabled.\r\nEnter any character (S or s will end program).\r\n";
  uint8_t ubSizeToSend = sizeof(aStringToSend);
  
  /**
    * @brief Variables used for character reception from PC Com port
    */
  __IO uint8_t      ubFinalCharReceived = 0;
  __IO uint32_t     ubReceivedChar;
  
  
  
  /* Private function prototypes -----------------------------------------------*/
  void     SystemClock_Config(void);
  void     Configure_USART1(void);
  void     StartTransfers(void);
  void     LED_Init(void);
  void     LED_On(void);
  void     LED_Blinking(uint32_t Period);
  void     LED_Off(void);
  void     UserButton_Init(void);
  void     WaitForUserButtonPress(void);
  void     WaitAndCheckEndOfTransfer(void);
  static void CPU_CACHE_Enable(void);
  
  /* Private functions ---------------------------------------------------------*/
  
  /**
    * @brief  Main program
    * @param  None
    * @retval None
    */
  int main(void)
  {
    /* Enable the CPU Cache */
    CPU_CACHE_Enable();
    
    /* Configure the system clock to 216 MHz */
    SystemClock_Config();
  
    /* Initialize LED1 */
    LED_Init();
  
    /* Set LED1 Off */
    LED_Off();
  
    /* Initialize User push-button in EXTI mode */
    UserButton_Init();
  
    /* Configure USART1 (USART IP configuration and related GPIO initialization) */
    Configure_USART1();
  
    /* Wait for User push-button press to start transfer */
    WaitForUserButtonPress();
    
    /* Initiate DMA transfers */
    StartTransfers();
    
    /* Wait for the end of the transfer and check received data */
    WaitAndCheckEndOfTransfer();
  
    /* Infinite loop */
    while (1)
    {
    }
  }
  
  /**
    * @brief  This function configures USART1.
    * @note   This function is used to :
    *         -1- Enable GPIO clock and configures the USART1 pins.
    *         -2- NVIC Configuration for USART1 interrupts.
    *         -3- Enable the USART1 peripheral clock and clock source.
    *         -4- Configure USART1 functional parameters.
    *         -5- Enable USART1.
    * @note   Peripheral configuration is minimal configuration from reset values.
    *         Thus, some useless LL unitary functions calls below are provided as
    *         commented examples - setting is default configuration from reset.
    * @param  None
    * @retval None
    */
  void Configure_USART1(void)
  {
    /* (1) Enable GPIO clock and configures the USART1 pins **********************/
    /*    (TX on PA.9, RX on PA.10)                         **********************/
    /*    (CTS on PA.11, RTS on PA.12)                      **********************/
  
    /* Enable the peripheral clock of GPIOA */
    LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOA);
  
    /* Configure TX Pin as : Alternate function, High Speed, PushPull, Pull up */
    LL_GPIO_SetPinMode(GPIOA, LL_GPIO_PIN_9, LL_GPIO_MODE_ALTERNATE);
    LL_GPIO_SetAFPin_8_15(GPIOA, LL_GPIO_PIN_9, LL_GPIO_AF_7);
    LL_GPIO_SetPinSpeed(GPIOA, LL_GPIO_PIN_9, LL_GPIO_SPEED_FREQ_HIGH);
    LL_GPIO_SetPinOutputType(GPIOA, LL_GPIO_PIN_9, LL_GPIO_OUTPUT_PUSHPULL);
    LL_GPIO_SetPinPull(GPIOA, LL_GPIO_PIN_9, LL_GPIO_PULL_UP);
  
    /* Configure RX Pin as : Alternate function, High Speed, PushPull, Pull up */
    LL_GPIO_SetPinMode(GPIOA, LL_GPIO_PIN_10, LL_GPIO_MODE_ALTERNATE);
    LL_GPIO_SetAFPin_8_15(GPIOA, LL_GPIO_PIN_10, LL_GPIO_AF_7);
    LL_GPIO_SetPinSpeed(GPIOA, LL_GPIO_PIN_10, LL_GPIO_SPEED_FREQ_HIGH);
    LL_GPIO_SetPinOutputType(GPIOA, LL_GPIO_PIN_10, LL_GPIO_OUTPUT_PUSHPULL);
    LL_GPIO_SetPinPull(GPIOA, LL_GPIO_PIN_10, LL_GPIO_PULL_UP);
  
    /* Configure CTS Pin as : Alternate function, High Speed, OpenDrain, Pull up */
    LL_GPIO_SetPinMode(GPIOA, LL_GPIO_PIN_11, LL_GPIO_MODE_ALTERNATE);
    LL_GPIO_SetAFPin_8_15(GPIOA, LL_GPIO_PIN_11, LL_GPIO_AF_7);
    LL_GPIO_SetPinSpeed(GPIOA, LL_GPIO_PIN_11, LL_GPIO_SPEED_FREQ_HIGH);
    LL_GPIO_SetPinOutputType(GPIOA, LL_GPIO_PIN_11, LL_GPIO_OUTPUT_OPENDRAIN);
    LL_GPIO_SetPinPull(GPIOA, LL_GPIO_PIN_11, LL_GPIO_PULL_UP);
  
    /* Configure RTS Pin as : Alternate function, High Speed, OpenDrain, Pull up */
    LL_GPIO_SetPinMode(GPIOA, LL_GPIO_PIN_12, LL_GPIO_MODE_ALTERNATE);
    LL_GPIO_SetAFPin_8_15(GPIOA, LL_GPIO_PIN_12, LL_GPIO_AF_7);
    LL_GPIO_SetPinSpeed(GPIOA, LL_GPIO_PIN_12, LL_GPIO_SPEED_FREQ_HIGH);
    LL_GPIO_SetPinOutputType(GPIOA, LL_GPIO_PIN_12, LL_GPIO_OUTPUT_OPENDRAIN);
    LL_GPIO_SetPinPull(GPIOA, LL_GPIO_PIN_12, LL_GPIO_PULL_UP);
  
    /* (2) NVIC Configuration for USART1 interrupts */
    /*  - Set priority for USART1_IRQn */
    /*  - Enable USART1_IRQn           */
    NVIC_SetPriority(USART1_IRQn, 0);  
    NVIC_EnableIRQ(USART1_IRQn);
  
    /* (3) Enable the USART1 peripheral clock and clock source ****************/
    LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_USART1);
  
    /* Set clock source */
    LL_RCC_SetUSARTClockSource(LL_RCC_USART1_CLKSOURCE_PCLK2);
  
    /* (4) Configure USART1 functional parameters ********************************/
    
    /* Disable USART1 prior modifying configuration registers */
    /* Note: Commented as corresponding to Reset value */
    // LL_USART_Disable(USART1);
    
    /* TX/RX direction */
    LL_USART_SetTransferDirection(USART1, LL_USART_DIRECTION_TX_RX);
  
    /* 8 data bit, 1 start bit, 1 stop bit, no parity */
    LL_USART_ConfigCharacter(USART1, LL_USART_DATAWIDTH_8B, LL_USART_PARITY_NONE, LL_USART_STOPBITS_1);
  
    /* Enable CTS/RTS Hardware Flow Control */
    LL_USART_SetHWFlowCtrl(USART1, LL_USART_HWCONTROL_RTS_CTS);
  
    /* Oversampling by 16 */
    /* Reset value is LL_USART_OVERSAMPLING_16 */
    // LL_USART_SetOverSampling(USART1, LL_USART_OVERSAMPLING_16);
  
    /* Set Baudrate to 115200 using APB frequency set to 108000000 Hz */
    /* Frequency available for USART peripheral can also be calculated through LL RCC macro */
    /* Ex :
        Periphclk = LL_RCC_GetUSARTClockFreq(Instance); or LL_RCC_GetUARTClockFreq(Instance); depending on USART/UART instance
    
        In this example, Peripheral Clock is expected to be equal to 108000000 Hz => equal to SystemCoreClock/2
    */
    LL_USART_SetBaudRate(USART1, SystemCoreClock/2, LL_USART_OVERSAMPLING_16, 115200); 
  
    /* (5) Enable USART *********************************************************/
    LL_USART_Enable(USART1);
  
    /* Enable RXNE and Error interrupts */
    LL_USART_EnableIT_RXNE(USART1);
    LL_USART_EnableIT_ERROR(USART1);
  }
  
  /**
    * @brief  This function initiates TX transfer
    * @param  None
    * @retval None
    */
  void StartTransfers(void)
  {
    /* Start transfer only if not already ongoing */
    if (ubSend == 0)
    {
      /* Start USART transmission : Will initiate TXE interrupt after TDR register is empty */
      LL_USART_TransmitData8(USART1, aStringToSend[ubSend++]); 
  
      /* Enable TXE interrupt */
      LL_USART_EnableIT_TXE(USART1); 
    }
  }
  
  /**
    * @brief  Initialize LED1.
    * @param  None
    * @retval None
    */
  void LED_Init(void)
  {
    /* Enable the LED1 Clock */
    LED1_GPIO_CLK_ENABLE();
  
    /* Configure IO in output push-pull mode to drive external LED1 */
    LL_GPIO_SetPinMode(LED1_GPIO_PORT, LED1_PIN, LL_GPIO_MODE_OUTPUT);
    /* Reset value is LL_GPIO_OUTPUT_PUSHPULL */
    //LL_GPIO_SetPinOutputType(LED1_GPIO_PORT, LED1_PIN, LL_GPIO_OUTPUT_PUSHPULL);
    /* Reset value is LL_GPIO_SPEED_FREQ_LOW */
    //LL_GPIO_SetPinSpeed(LED1_GPIO_PORT, LED1_PIN, LL_GPIO_SPEED_FREQ_LOW);
    /* Reset value is LL_GPIO_PULL_NO */
    //LL_GPIO_SetPinPull(LED1_GPIO_PORT, LED1_PIN, LL_GPIO_PULL_NO);
  }
  
  /**
    * @brief  Turn-on LED1.
    * @param  None
    * @retval None
    */
  void LED_On(void)
  {
    /* Turn LED1 on */
    LL_GPIO_SetOutputPin(LED1_GPIO_PORT, LED1_PIN);
  }
  
  /**
    * @brief  Turn-off LED1.
    * @param  None
    * @retval None
    */
  void LED_Off(void)
  {
    /* Turn LED1 off */
    LL_GPIO_ResetOutputPin(LED1_GPIO_PORT, LED1_PIN);
  }
  
  /**
    * @brief  Set LED1 to Blinking mode for an infinite loop (toggle period based on value provided as input parameter).
    * @param  Period : Period of time (in ms) between each toggling of LED
    *   This parameter can be user defined values. Pre-defined values used in that example are :
    *     @arg LED_BLINK_FAST : Fast Blinking
    *     @arg LED_BLINK_SLOW : Slow Blinking
    *     @arg LED_BLINK_ERROR : Error specific Blinking
    * @retval None
    */
  void LED_Blinking(uint32_t Period)
  {
    /* Toggle LED1 in an infinite loop */
    while (1)
    {
      LL_GPIO_TogglePin(LED1_GPIO_PORT, LED1_PIN);  
      LL_mDelay(Period);
    }
  }
  
  /**
    * @brief  Configures User push-button in GPIO or EXTI Line Mode.
    * @param  None 
    * @retval None
    */
  void UserButton_Init(void)
  {
    /* Enable the BUTTON Clock */
    USER_BUTTON_GPIO_CLK_ENABLE();
    
    /* Configure GPIO for BUTTON */
    LL_GPIO_SetPinMode(USER_BUTTON_GPIO_PORT, USER_BUTTON_PIN, LL_GPIO_MODE_INPUT);
    LL_GPIO_SetPinPull(USER_BUTTON_GPIO_PORT, USER_BUTTON_PIN, LL_GPIO_PULL_NO);
  
    /* Connect External Line to the GPIO*/
    USER_BUTTON_SYSCFG_SET_EXTI();
  
    /* Enable a rising trigger EXTI_Line15_10 Interrupt */
    USER_BUTTON_EXTI_LINE_ENABLE();
    USER_BUTTON_EXTI_FALLING_TRIG_ENABLE();
  
    /* Configure NVIC for USER_BUTTON_EXTI_IRQn */
    NVIC_SetPriority(USER_BUTTON_EXTI_IRQn, 3);  
    NVIC_EnableIRQ(USER_BUTTON_EXTI_IRQn); 
  }
  
  /**
    * @brief  Wait for User push-button press to start transfer.
    * @param  None 
    * @retval None
    */
    /*  */
  void WaitForUserButtonPress(void)
  {
    while (ubButtonPress == 0)
    {
      LL_GPIO_TogglePin(LED1_GPIO_PORT, LED1_PIN);
      LL_mDelay(LED_BLINK_FAST);
    }
    /* Ensure that LED1 is turned Off */
    LED_Off();
  }
  
  /**
    * @brief  Wait end of transfer and check if received Data are well.
    * @param  None 
    * @retval None
    */
  void WaitAndCheckEndOfTransfer(void)
  {
    /* Wait end of reception from USART1 */
    while (ubFinalCharReceived != 1)
    {
    }
  
    /* Turn On Led indicating final character has been received */
    LED_On();
  }
  
  /**
    * @brief  System Clock Configuration
    *         The system Clock is configured as follow :
    *            System Clock source            = PLL (HSE)
    *            SYSCLK(Hz)                     = 216000000
    *            HCLK(Hz)                       = 216000000
    *            AHB Prescaler                  = 1
    *            APB1 Prescaler                 = 4
    *            APB2 Prescaler                 = 2
    *            HSI Frequency(Hz)              = 8000000
    *            PLL_M                          = 8
    *            PLL_N                          = 432
    *            PLL_P                          = 2
    *            VDD(V)                         = 3.3
    *            Main regulator output voltage  = Scale1 mode
    *            Flash Latency(WS)              = 7
    * @param  None
    * @retval None
    */
  void SystemClock_Config(void)
  {
    /* Enable HSE clock */
    LL_RCC_HSE_EnableBypass();
    LL_RCC_HSE_Enable();
    while(LL_RCC_HSE_IsReady() != 1)
    {
    };
  
    /* Set FLASH latency */
    LL_FLASH_SetLatency(LL_FLASH_LATENCY_7);
  
    /* Enable PWR clock */
    LL_APB1_GRP1_EnableClock(LL_APB1_GRP1_PERIPH_PWR);
  
    /* Activation OverDrive Mode */
    LL_PWR_EnableOverDriveMode();
    while(LL_PWR_IsActiveFlag_OD() != 1)
    {
    };
  
    /* Activation OverDrive Switching */
    LL_PWR_EnableOverDriveSwitching();
    while(LL_PWR_IsActiveFlag_ODSW() != 1)
    {
    };
  
    /* Main PLL configuration and activation */
    LL_RCC_PLL_ConfigDomain_SYS(LL_RCC_PLLSOURCE_HSE, LL_RCC_PLLM_DIV_8, 432, LL_RCC_PLLP_DIV_2);
    LL_RCC_PLL_Enable();
    while(LL_RCC_PLL_IsReady() != 1)
    {
    };
  
    /* Sysclk activation on the main PLL */
    LL_RCC_SetAHBPrescaler(LL_RCC_SYSCLK_DIV_1);
    LL_RCC_SetSysClkSource(LL_RCC_SYS_CLKSOURCE_PLL);
    while(LL_RCC_GetSysClkSource() != LL_RCC_SYS_CLKSOURCE_STATUS_PLL)
    {
    };
  
    /* Set APB1 & APB2 prescaler */
    LL_RCC_SetAPB1Prescaler(LL_RCC_APB1_DIV_4);
    LL_RCC_SetAPB2Prescaler(LL_RCC_APB2_DIV_2);
  
    /* Set systick to 1ms */
    SysTick_Config(216000000 / 1000);
  
    /* Update CMSIS variable (which can be updated also through SystemCoreClockUpdate function) */
    SystemCoreClock = 216000000;
  }
  
  /******************************************************************************/
  /*   USER IRQ HANDLER TREATMENT Functions                                     */
  /******************************************************************************/
  /**
    * @brief  Function to manage User push-button
    * @param  None
    * @retval None
    */
  void UserButton_Callback(void)
  {
    /* Update User push-button variable : to be checked in waiting loop in main program */
    ubButtonPress = 1;
  }
  
  /**
    * @brief  Function called for achieving next TX Byte sending
    * @param  None
    * @retval None
    */
  void USART_TXEmpty_Callback(void)
  {
    if(ubSend == (ubSizeToSend - 1))
    {
      /* Disable TXE interrupt */
      LL_USART_DisableIT_TXE(USART1);
  
      /* Enable TC interrupt */
      LL_USART_EnableIT_TC(USART1);
    }
  
    /* Fill TDR with a new char */
    LL_USART_TransmitData8(USART1, aStringToSend[ubSend++]);
  }
  
  /**
    * @brief  Function called at completion of last byte transmission
    * @param  None
    * @retval None
    */
  void USART_CharTransmitComplete_Callback(void)
  {
    if(ubSend == sizeof(aStringToSend))
    {
      ubSend = 0;
  
      /* Disable TC interrupt */
      LL_USART_DisableIT_TC(USART1);
    }
  }
  
  /**
    * @brief  Function called from USART IRQ Handler when RXNE flag is set
    *         Function is in charge of reading character received on USART RX line.
    * @param  None
    * @retval None
    */
  void USART_CharReception_Callback(void)
  {
  __IO uint32_t received_char;
  
    /* Read Received character. RXNE flag is cleared by reading of RDR register */
    received_char = LL_USART_ReceiveData8(USART1);
  
    /* Check if received value is corresponding to specific one : S or s */
    if ((received_char == 'S') || (received_char == 's'))
    {
      ubFinalCharReceived = 1;
  
      /* Disable RXNE interrupt */
      LL_USART_DisableIT_RXNE(USART1);
    }
  
    /* Echo received character on TX */
    LL_USART_TransmitData8(USART1, received_char);
  }
  
  /**
    * @brief  Function called in case of error detected in USART IT Handler
    * @param  None
    * @retval None
    */
  void Error_Callback(void)
  {
    __IO uint32_t isr_reg;
  
    /* Disable USART1_IRQn */
    NVIC_DisableIRQ(USART1_IRQn);
    
    /* Error handling example :
      - Read USART ISR register to identify flag that leads to IT raising
      - Perform corresponding error handling treatment according to flag
    */
    isr_reg = LL_USART_ReadReg(USART1, ISR);
    if (isr_reg & LL_USART_ISR_NE)
    {
      /* case Noise Error flag is raised : Clear NF Flag */
      LL_USART_ClearFlag_NE(USART1);
    }
    else
    {
      /* Unexpected IT source : Set LED to Blinking mode to indicate error occurs */
      LED_Blinking(LED_BLINK_ERROR);
    }
  }
  
  #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", file, line) */
  
    /* Infinite loop */
    while (1)
    {
    }
  }
  #endif
  /**
    * @brief  CPU L1-Cache enable.
    * @param  None
    * @retval None
    */
  static void CPU_CACHE_Enable(void)
  {
    /* Enable I-Cache */
    SCB_EnableICache();
  
    /* Enable D-Cache */
    SCB_EnableDCache();
  }
  
  /**
    * @}
    */
  
  /**
    * @}
    */
  
  /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
  