Initialization and de-initialization functions

Extended Initialization and Configuration Functions. More...

Functions
HAL_StatusTypeDef	HAL_RS485Ex_Init (UART_HandleTypeDef *huart, uint32_t Polarity, uint32_t AssertionTime, uint32_t DeassertionTime)
	Initialize the RS485 Driver enable feature according to the specified parameters in the UART_InitTypeDef and creates the associated handle. More...

Detailed Description

Extended Initialization and Configuration Functions.

===============================================================================
            ##### Initialization and Configuration functions #####
 ===============================================================================
    [..]
    This subsection provides a set of functions allowing to initialize the USARTx or the UARTy
    in asynchronous mode.
      (+) For the asynchronous mode the parameters below can be configured:
        (++) Baud Rate
        (++) Word Length
        (++) Stop Bit
        (++) Parity: If the parity is enabled, then the MSB bit of the data written
             in the data register is transmitted but is changed by the parity bit.
        (++) Hardware flow control
        (++) Receiver/transmitter modes
        (++) Over Sampling Method
        (++) One-Bit Sampling Method
      (+) For the asynchronous mode, the following advanced features can be configured as well:
        (++) TX and/or RX pin level inversion
        (++) data logical level inversion
        (++) RX and TX pins swap
        (++) RX overrun detection disabling
        (++) DMA disabling on RX error
        (++) MSB first on communication line
        (++) auto Baud rate detection
    [..]
    The HAL_RS485Ex_Init() API follows the UART RS485 mode configuration
     procedures (details for the procedures are available in reference manual).

Depending on the frame length defined by the M1 and M0 bits (7-bit, 8-bit or 9-bit), the possible UART formats are listed in the following table.

Table 1. UART frame format. +--------------------------------------------------------------------—+ | M1 bit | M0 bit | PCE bit | UART frame | |------—|------—|--------—|------------------------------------—| | 0 | 0 | 0 | | SB | 8 bit data | STB | | |------—|------—|--------—|------------------------------------—| | 0 | 0 | 1 | | SB | 7 bit data | PB | STB | | |------—|------—|--------—|------------------------------------—| | 0 | 1 | 0 | | SB | 9 bit data | STB | | |------—|------—|--------—|------------------------------------—| | 0 | 1 | 1 | | SB | 8 bit data | PB | STB | | |------—|------—|--------—|------------------------------------—| | 1 | 0 | 0 | | SB | 7 bit data | STB | | |------—|------—|--------—|------------------------------------—| | 1 | 0 | 1 | | SB | 6 bit data | PB | STB | | +--------------------------------------------------------------------—+

Function Documentation

HAL_RS485Ex_Init()

HAL_StatusTypeDef HAL_RS485Ex_Init	(	UART_HandleTypeDef *	huart,
		uint32_t	Polarity,
		uint32_t	AssertionTime,
		uint32_t	DeassertionTime
	)

Initialize the RS485 Driver enable feature according to the specified parameters in the UART_InitTypeDef and creates the associated handle.

Parameters

huart	UART handle.
Polarity	Select the driver enable polarity. This parameter can be one of the following values: UART_DE_POLARITY_HIGH DE signal is active high UART_DE_POLARITY_LOW DE signal is active low
AssertionTime	Driver Enable assertion time: 5-bit value defining the time between the activation of the DE (Driver Enable) signal and the beginning of the start bit. It is expressed in sample time units (1/8 or 1/16 bit time, depending on the oversampling rate)
DeassertionTime	Driver Enable deassertion time: 5-bit value defining the time between the end of the last stop bit, in a transmitted message, and the de-activation of the DE (Driver Enable) signal. It is expressed in sample time units (1/8 or 1/16 bit time, depending on the oversampling rate).

Return values

HAL

status

Definition at line 170 of file stm32l4xx_hal_uart_ex.c.

{
  uint32_t temp;

  /* Check the UART handle allocation */
  if (huart == NULL)
  {
    return HAL_ERROR;
  }
  /* Check the Driver Enable UART instance */
  assert_param(IS_UART_DRIVER_ENABLE_INSTANCE(huart->Instance));

  /* Check the Driver Enable polarity */
  assert_param(IS_UART_DE_POLARITY(Polarity));

  /* Check the Driver Enable assertion time */
  assert_param(IS_UART_ASSERTIONTIME(AssertionTime));

  /* Check the Driver Enable deassertion time */
  assert_param(IS_UART_DEASSERTIONTIME(DeassertionTime));

  if (huart->gState == HAL_UART_STATE_RESET)
  {
    /* Allocate lock resource and initialize it */
    huart->Lock = HAL_UNLOCKED;

#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)
    UART_InitCallbacksToDefault(huart);

    if (huart->MspInitCallback == NULL)
    {
      huart->MspInitCallback = HAL_UART_MspInit;
    }

    /* Init the low level hardware */
    huart->MspInitCallback(huart);
#else
    /* Init the low level hardware : GPIO, CLOCK, CORTEX */
    HAL_UART_MspInit(huart);
#endif /* (USE_HAL_UART_REGISTER_CALLBACKS) */
  }

  huart->gState = HAL_UART_STATE_BUSY;

  /* Disable the Peripheral */
  __HAL_UART_DISABLE(huart);

  /* Set the UART Communication parameters */
  if (UART_SetConfig(huart) == HAL_ERROR)
  {
    return HAL_ERROR;
  }

  if (huart->AdvancedInit.AdvFeatureInit != UART_ADVFEATURE_NO_INIT)
  {
    UART_AdvFeatureConfig(huart);
  }

  /* Enable the Driver Enable mode by setting the DEM bit in the CR3 register */
  SET_BIT(huart->Instance->CR3, USART_CR3_DEM);

  /* Set the Driver Enable polarity */
  MODIFY_REG(huart->Instance->CR3, USART_CR3_DEP, Polarity);

  /* Set the Driver Enable assertion and deassertion times */
  temp = (AssertionTime << UART_CR1_DEAT_ADDRESS_LSB_POS);
  temp |= (DeassertionTime << UART_CR1_DEDT_ADDRESS_LSB_POS);
  MODIFY_REG(huart->Instance->CR1, (USART_CR1_DEDT | USART_CR1_DEAT), temp);

  /* Enable the Peripheral */
  __HAL_UART_ENABLE(huart);

  /* TEACK and/or REACK to check before moving huart->gState and huart->RxState to Ready */
  return (UART_CheckIdleState(huart));
}