STM32CubeF4/Projects/STM32F411RE-Nucleo/Examples_LL/USART/USART_HardwareFlowControl/Src/main.c

/**
  ******************************************************************************
  * @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 STM32F4xx USART LL API.
  *          Peripheral initialization done using LL unitary services functions.
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2017 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */

/* Includes ------------------------------------------------------------------*/
#include "main.h"

/** @addtogroup STM32F4xx_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[] = "STM32F4xx 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);

/* Private functions ---------------------------------------------------------*/

/**
  * @brief  Main program
  * @param  None
  * @retval None
  */
int main(void)
{
  /* Configure the system clock to 100 MHz */
  SystemClock_Config();

  /* Initialize LED2 */
  LED_Init();

  /* Set LED2 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);

  /* (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 100000000 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 100000000 Hz => equal to SystemCoreClock
  */
  LL_USART_SetBaudRate(USART1, SystemCoreClock, 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 DR register is empty */
    LL_USART_TransmitData8(USART1, aStringToSend[ubSend++]); 

    /* Enable TXE interrupt */
    LL_USART_EnableIT_TXE(USART1); 
  }
}

/**
  * @brief  Initialize LED2.
  * @param  None
  * @retval None
  */
void LED_Init(void)
{
  /* Enable the LED2 Clock */
  LED2_GPIO_CLK_ENABLE();

  /* Configure IO in output push-pull mode to drive external LED2 */
  LL_GPIO_SetPinMode(LED2_GPIO_PORT, LED2_PIN, LL_GPIO_MODE_OUTPUT);
  /* Reset value is LL_GPIO_OUTPUT_PUSHPULL */
  //LL_GPIO_SetPinOutputType(LED2_GPIO_PORT, LED2_PIN, LL_GPIO_OUTPUT_PUSHPULL);
  /* Reset value is LL_GPIO_SPEED_FREQ_LOW */
  //LL_GPIO_SetPinSpeed(LED2_GPIO_PORT, LED2_PIN, LL_GPIO_SPEED_FREQ_LOW);
  /* Reset value is LL_GPIO_PULL_NO */
  //LL_GPIO_SetPinPull(LED2_GPIO_PORT, LED2_PIN, LL_GPIO_PULL_NO);
}

/**
  * @brief  Turn-on LED2.
  * @param  None
  * @retval None
  */
void LED_On(void)
{
  /* Turn LED2 on */
  LL_GPIO_SetOutputPin(LED2_GPIO_PORT, LED2_PIN);
}

/**
  * @brief  Turn-off LED2.
  * @param  None
  * @retval None
  */
void LED_Off(void)
{
  /* Turn LED2 off */
  LL_GPIO_ResetOutputPin(LED2_GPIO_PORT, LED2_PIN);
}

/**
  * @brief  Set LED2 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 LED2 in an infinite loop */
  while (1)
  {
    LL_GPIO_TogglePin(LED2_GPIO_PORT, LED2_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 EXTI13 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(LED2_GPIO_PORT, LED2_PIN);
    LL_mDelay(LED_BLINK_FAST);
  }
  /* Ensure that LED2 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)                     = 100000000
  *            HCLK(Hz)                       = 100000000
  *            AHB Prescaler                  = 1
  *            APB1 Prescaler                 = 2
  *            APB2 Prescaler                 = 1
  *            HSE Frequency(Hz)              = 8000000
  *            PLL_M                          = 8
  *            PLL_N                          = 400
  *            PLL_P                          = 4
  *            VDD(V)                         = 3.3
  *            Main regulator output voltage  = Scale1 mode
  *            Flash Latency(WS)              = 3
  * @param  None
  * @retval None
  */
void SystemClock_Config(void)
{
  /* Enable HSE oscillator */
  LL_RCC_HSE_EnableBypass();
  LL_RCC_HSE_Enable();
  while(LL_RCC_HSE_IsReady() != 1)
  {
  };

  /* Set FLASH latency */
  LL_FLASH_SetLatency(LL_FLASH_LATENCY_3);

  /* Main PLL configuration and activation */
  LL_RCC_PLL_ConfigDomain_SYS(LL_RCC_PLLSOURCE_HSE, LL_RCC_PLLM_DIV_8, 400, LL_RCC_PLLP_DIV_4);
  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_2);
  LL_RCC_SetAPB2Prescaler(LL_RCC_APB2_DIV_1);

  /* Set systick to 1ms */
  SysTick_Config(100000000 / 1000);

  /* Update CMSIS variable (which can be updated also through SystemCoreClockUpdate function) */
  SystemCoreClock = 100000000;
}

/******************************************************************************/
/*   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 DR 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 DR 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 sr_reg;

  /* Disable USART1_IRQn */
  NVIC_DisableIRQ(USART1_IRQn);
  
  /* Error handling example :
    - Read USART SR register to identify flag that leads to IT raising
    - Perform corresponding error handling treatment according to flag
  */
  sr_reg = LL_USART_ReadReg(USART1, SR);
  if (sr_reg & LL_USART_SR_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

/**
  * @}
  */

/**
  * @}
  */