stm32f2xx_usart.c

STM32+Grlib

/**
  ******************************************************************************
  * @file    stm32f2xx_usart.c
  * @author  MCD Application Team
  * @version V1.0.0
  * @date    18-April-2011
  * @brief   This file provides firmware functions to manage the following 
  *          functionalities of the Universal synchronous asynchronous receiver
  *          transmitter (USART):           
  *           - Initialization and Configuration
  *           - Data transfers
  *           - Multi-Processor Communication
  *           - LIN mode
  *           - Half-duplex mode
  *           - Smartcard mode
  *           - IrDA mode
  *           - DMA transfers management
  *           - Interrupts and flags management 
  *           
  *  @verbatim
  *      
  *          ===================================================================
  *                                 How to use this driver
  *          ===================================================================
  *          1. Enable peripheral clock using the follwoing functions
  *             RCC_APB2PeriphClockCmd(RCC_APB2Periph_USARTx, ENABLE) for USART1 and USART6 
  *             RCC_APB1PeriphClockCmd(RCC_APB1Periph_USARTx, ENABLE) for USART2, USART3, UART4 or UART5.
  *
  *          2.  According to the USART mode, enable the GPIO clocks using 
  *              RCC_AHB1PeriphClockCmd() function. (The I/O can be TX, RX, CTS, 
  *              or/and SCLK). 
  *
  *          3. Peripheral's alternate function: 
  *                 - Connect the pin to the desired peripherals' Alternate 
  *                   Function (AF) using GPIO_PinAFConfig() function
  *                 - Configure the desired pin in alternate function by:
  *                   GPIO_InitStruct->GPIO_Mode = GPIO_Mode_AF
  *                 - Select the type, pull-up/pull-down and output speed via 
  *                   GPIO_PuPd, GPIO_OType and GPIO_Speed members
  *                 - Call GPIO_Init() function
  *        
  *          4. Program the Baud Rate, Word Length , Stop Bit, Parity, Hardware 
  *             flow control and Mode(Receiver/Transmitter) using the USART_Init()
  *             function.
  *
  *          5. For synchronous mode, enable the clock and program the polarity,
  *             phase and last bit using the USART_ClockInit() function.
  *
  *          5. Enable the NVIC and the corresponding interrupt using the function 
  *             USART_ITConfig() if you need to use interrupt mode. 
  *
  *          6. When using the DMA mode 
  *                   - Configure the DMA using DMA_Init() function
  *                   - Active the needed channel Request using USART_DMACmd() function
  * 
  *          7. Enable the USART using the USART_Cmd() function.
  * 
  *          8. Enable the DMA using the DMA_Cmd() function, when using DMA mode. 
  *
  *          Refer to Multi-Processor, LIN, half-duplex, Smartcard, IrDA sub-sections
  *          for more details
  *          
  *          In order to reach higher communication baudrates, it is possible to
  *          enable the oversampling by 8 mode using the function USART_OverSampling8Cmd().
  *          This function should be called after enabling the USART clock (RCC_APBxPeriphClockCmd())
  *          and before calling the function USART_Init().
  *          
  *  @endverbatim
  *        
  ******************************************************************************
  * @attention
  *
  * THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
  * WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE
  * TIME. AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY
  * DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING
  * FROM THE CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE
  * CODING INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
  *
  * <h2><center>&copy; COPYRIGHT 2011 STMicroelectronics</center></h2>
  ******************************************************************************  
  */ 

/* Includes ------------------------------------------------------------------*/
#include "stm32f2xx_usart.h"
#include "stm32f2xx_rcc.h"

/** @addtogroup STM32F2xx_StdPeriph_Driver
  * @{
  */

/** @defgroup USART 
  * @brief USART driver modules
  * @{
  */

/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/

/*!< USART CR1 register clear Mask ((~(uint16_t)0xE9F3)) */
#define CR1_CLEAR_MASK            ((uint16_t)(USART_CR1_M | USART_CR1_PCE | \
                                              USART_CR1_PS | USART_CR1_TE | \
                                              USART_CR1_RE))

/*!< USART CR2 register clock bits clear Mask ((~(uint16_t)0xF0FF)) */
#define CR2_CLOCK_CLEAR_MASK      ((uint16_t)(USART_CR2_CLKEN | USART_CR2_CPOL | \
                                              USART_CR2_CPHA | USART_CR2_LBCL))

/*!< USART CR3 register clear Mask ((~(uint16_t)0xFCFF)) */
#define CR3_CLEAR_MASK            ((uint16_t)(USART_CR3_RTSE | USART_CR3_CTSE))

/*!< USART Interrupts mask */
#define IT_MASK                   ((uint16_t)0x001F)

/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*/

/** @defgroup USART_Private_Functions
  * @{
  */

/** @defgroup USART_Group1 Initialization and Configuration functions
 *  @brief   Initialization and Configuration functions 
 *
@verbatim   
 ===============================================================================
                  Initialization and Configuration functions
 ===============================================================================  

  This subsection provides a set of functions allowing to initialize the USART 
  in asynchronous and in synchronous modes.
   - For the asynchronous mode only these parameters 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.
          Depending on the frame length defined by the M bit (8-bits or 9-bits),
          the possible USART frame formats are as listed in the following table:
   +-------------------------------------------------------------+     
   |   M bit |  PCE bit  |            USART frame                |
   |---------------------|---------------------------------------|             
   |    0    |    0      |    | SB | 8 bit data | STB |          |
   |---------|-----------|---------------------------------------|  
   |    0    |    1      |    | SB | 7 bit data | PB | STB |     |
   |---------|-----------|---------------------------------------|  
   |    1    |    0      |    | SB | 9 bit data | STB |          |
   |---------|-----------|---------------------------------------|  
   |    1    |    1      |    | SB | 8 bit data | PB | STB |     |
   +-------------------------------------------------------------+            
        - Hardware flow control
        - Receiver/transmitter modes

  The USART_Init() function follows the USART  asynchronous configuration procedure
  (details for the procedure are available in reference manual (RM0033)).

  - For the synchronous mode in addition to the asynchronous mode parameters these 
    parameters should be also configured:
        - USART Clock Enabled
        - USART polarity
        - USART phase
        - USART LastBit
  
  These parameters can be configured using the USART_ClockInit() function.

@endverbatim
  * @{
  */
  
/**
  * @brief  Deinitializes the USARTx peripheral registers to their default reset values.
  * @param  USARTx: where x can be 1, 2, 3, 4, 5 or 6 to select the USART or 
  *         UART peripheral.
  * @retval None
  */
void USART_DeInit(USART_TypeDef* USARTx)
{
  /* Check the parameters */
  assert_param(IS_USART_ALL_PERIPH(USARTx));

  if (USARTx == USART1)
  {
    RCC_APB2PeriphResetCmd(RCC_APB2Periph_USART1, ENABLE);
    RCC_APB2PeriphResetCmd(RCC_APB2Periph_USART1, DISABLE);
  }
  else if (USARTx == USART2)
  {
    RCC_APB1PeriphResetCmd(RCC_APB1Periph_USART2, ENABLE);
    RCC_APB1PeriphResetCmd(RCC_APB1Periph_USART2, DISABLE);
  }
  else if (USARTx == USART3)
  {
    RCC_APB1PeriphResetCmd(RCC_APB1Periph_USART3, ENABLE);
    RCC_APB1PeriphResetCmd(RCC_APB1Periph_USART3, DISABLE);
  }    
  else if (USARTx == UART4)
  {
    RCC_APB1PeriphResetCmd(RCC_APB1Periph_UART4, ENABLE);
    RCC_APB1PeriphResetCmd(RCC_APB1Periph_UART4, DISABLE);
  }
  else if (USARTx == UART5)
  {
    RCC_APB1PeriphResetCmd(RCC_APB1Periph_UART5, ENABLE);
    RCC_APB1PeriphResetCmd(RCC_APB1Periph_UART5, DISABLE);
  }     
  else
  {
    if (USARTx == USART6)
    { 
      RCC_APB2PeriphResetCmd(RCC_APB2Periph_USART6, ENABLE);
      RCC_APB2PeriphResetCmd(RCC_APB2Periph_USART6, DISABLE);
    }
  }
}

/**
  * @brief  Initializes the USARTx peripheral according to the specified
  *         parameters in the USART_InitStruct .
  * @param  USARTx: where x can be 1, 2, 3, 4, 5 or 6 to select the USART or 
  *         UART peripheral.
  * @param  USART_InitStruct: pointer to a USART_InitTypeDef structure that contains
  *         the configuration information for the specified USART peripheral.
  * @retval None
  */
void USART_Init(USART_TypeDef* USARTx, USART_InitTypeDef* USART_InitStruct)
{
  uint32_t tmpreg = 0x00, apbclock = 0x00;
  uint32_t integerdivider = 0x00;
  uint32_t fractionaldivider = 0x00;
  RCC_ClocksTypeDef RCC_ClocksStatus;

  /* Check the parameters */
  assert_param(IS_USART_ALL_PERIPH(USARTx));
  assert_param(IS_USART_BAUDRATE(USART_InitStruct->USART_BaudRate));  
  assert_param(IS_USART_WORD_LENGTH(USART_InitStruct->USART_WordLength));
  assert_param(IS_USART_STOPBITS(USART_InitStruct->USART_StopBits));
  assert_param(IS_USART_PARITY(USART_InitStruct->USART_Parity));
  assert_param(IS_USART_MODE(USART_InitStruct->USART_Mode));
  assert_param(IS_USART_HARDWARE_FLOW_CONTROL(USART_InitStruct->USART_HardwareFlowControl));

  /* The hardware flow control is available only for USART1, USART2, USART3 and USART6 */
  if (USART_InitStruct->USART_HardwareFlowControl != USART_HardwareFlowControl_None)
  {
    assert_param(IS_USART_1236_PERIPH(USARTx));
  }

/*---------------------------- USART CR2 Configuration -----------------------*/
  tmpreg = USARTx->CR2;

  /* Clear STOP[13:12] bits */
  tmpreg &= (uint32_t)~((uint32_t)USART_CR2_STOP);

  /* Configure the USART Stop Bits, Clock, CPOL, CPHA and LastBit :
      Set STOP[13:12] bits according to USART_StopBits value */
  tmpreg |= (uint32_t)USART_InitStruct->USART_StopBits;
  
  /* Write to USART CR2 */
  USARTx->CR2 = (uint16_t)tmpreg;

/*---------------------------- USART CR1 Configuration -----------------------*/
  tmpreg = USARTx->CR1;

  /* Clear M, PCE, PS, TE and RE bits */
  tmpreg &= (uint32_t)~((uint32_t)CR1_CLEAR_MASK);

  /* Configure the USART Word Length, Parity and mode: 
     Set the M bits according to USART_WordLength value 
     Set PCE and PS bits according to USART_Parity value
     Set TE and RE bits according to USART_Mode value */
  tmpreg |= (uint32_t)USART_InitStruct->USART_WordLength | USART_InitStruct->USART_Parity |
            USART_InitStruct->USART_Mode;

  /* Write to USART CR1 */
  USARTx->CR1 = (uint16_t)tmpreg;

/*---------------------------- USART CR3 Configuration -----------------------*/  
  tmpreg = USARTx->CR3;

  /* Clear CTSE and RTSE bits */
  tmpreg &= (uint32_t)~((uint32_t)CR3_CLEAR_MASK);

  /* Configure the USART HFC : 
      Set CTSE and RTSE bits according to USART_HardwareFlowControl value */
  tmpreg |= USART_InitStruct->USART_HardwareFlowControl;

  /* Write to USART CR3 */
  USARTx->CR3 = (uint16_t)tmpreg;

/*---------------------------- USART BRR Configuration -----------------------*/
  /* Configure the USART Baud Rate */
  RCC_GetClocksFreq(&RCC_ClocksStatus);

  if ((USARTx == USART1) || (USARTx == USART6))
  {
    apbclock = RCC_ClocksStatus.PCLK2_Frequency;
  }
  else
  {
    apbclock = RCC_ClocksStatus.PCLK1_Frequency;
  }
  
  /* Determine the integer part */
  if ((USARTx->CR1 & USART_CR1_OVER8) != 0)
  {
    /* Integer part computing in case Oversampling mode is 8 Samples */
    integerdivider = ((25 * apbclock) / (2 * (USART_InitStruct->USART_BaudRate)));    
  }
  else /* if ((USARTx->CR1 & USART_CR1_OVER8) == 0) */
  {
    /* Integer part computing in case Oversampling mode is 16 Samples */
    integerdivider = ((25 * apbclock) / (4 * (USART_InitStruct->USART_BaudRate)));    
  }
  tmpreg = (integerdivider / 100) << 4;

  /* Determine the fractional part */
  fractionaldivider = integerdivider - (100 * (tmpreg >> 4));

  /* Implement the fractional part in the register */
  if ((USARTx->CR1 & USART_CR1_OVER8) != 0)
  {
    tmpreg |= ((((fractionaldivider * 8) + 50) / 100)) & ((uint8_t)0x07);
  }
  else /* if ((USARTx->CR1 & USART_CR1_OVER8) == 0) */
  {
    tmpreg |= ((((fractionaldivider * 16) + 50) / 100)) & ((uint8_t)0x0F);
  }
  
  /* Write to USART BRR register */
  USARTx->BRR = (uint16_t)tmpreg;
}

/**
  * @brief  Fills each USART_InitStruct member with its default value.
  * @param  USART_InitStruct: pointer to a USART_InitTypeDef structure which will
  *         be initialized.
  * @retval None
  */
void USART_StructInit(USART_InitTypeDef* USART_InitStruct)
{
  /* USART_InitStruct members default value */
  USART_InitStruct->USART_BaudRate = 9600;
  USART_InitStruct->USART_WordLength = USART_WordLength_8b;
  USART_InitStruct->USART_StopBits = USART_StopBits_1;
  USART_InitStruct->USART_Parity = USART_Parity_No ;
  USART_InitStruct->USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
  USART_InitStruct->USART_HardwareFlowControl = USART_HardwareFlowControl_None;  
}

/**
  * @brief  Initializes the USARTx peripheral Clock according to the 
  *         specified parameters in the USART_ClockInitStruct .
  * @param  USARTx: where x can be 1, 2, 3 or 6 to select the USART peripheral.
  * @param  USART_ClockInitStruct: pointer to a USART_ClockInitTypeDef structure that
  *         contains the configuration information for the specified  USART peripheral.
  * @note   The Smart Card and Synchronous modes are not available for UART4 and UART5.    
  * @retval None
  */
void USART_ClockInit(USART_TypeDef* USARTx, USART_ClockInitTypeDef* USART_ClockInitStruct)
{
  uint32_t tmpreg = 0x00;
  /* Check the parameters */
  assert_param(IS_USART_1236_PERIPH(USARTx));
  assert_param(IS_USART_CLOCK(USART_ClockInitStruct->USART_Clock));
  assert_param(IS_USART_CPOL(USART_ClockInitStruct->USART_CPOL));