stm32f0xx_usart.c

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/**
  ******************************************************************************
  * @file    stm32f0xx_usart.c
  * @author  MCD Application Team
  * @version V1.0.0
  * @date    23-March-2012
  * @brief   This file provides firmware functions to manage the following 
  *          functionalities of the Universal synchronous asynchronous receiver
  *          transmitter (USART):
  *           + Initialization and Configuration
  *           + STOP Mode
  *           + AutoBaudRate
  *           + Data transfers
  *           + Multi-Processor Communication
  *           + LIN mode
  *           + Half-duplex mode
  *           + Smartcard mode
  *           + IrDA mode
  *           + RS485 mode  
  *           + DMA transfers management
  *           + Interrupts and flags management
  *           
  *  @verbatim
 ===============================================================================
                       ##### How to use this driver #####
 ===============================================================================
    [..]
        (#) Enable peripheral clock using RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE)
            function for USART1 or using RCC_APB1PeriphClockCmd(RCC_APB1Periph_USARTx, ENABLE)
            function for USART2 and USART3.
        (#) According to the USART mode, enable the GPIO clocks using 
            RCC_AHBPeriphClockCmd() function. (The I/O can be TX, RX, CTS, 
            or and SCLK). 
        (#) 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.        
        (#) Program the Baud Rate, Word Length , Stop Bit, Parity, Hardware 
            flow control and Mode(Receiver/Transmitter) using the SPI_Init()
            function.  
        (#) For synchronous mode, enable the clock and program the polarity,
            phase and last bit using the USART_ClockInit() function.  
        (#) Enable the NVIC and the corresponding interrupt using the function 
            USART_ITConfig() if you need to use interrupt mode.   
        (#) When using the DMA mode: 
            (++) Configure the DMA using DMA_Init() function.
            (++) Active the needed channel Request using USART_DMACmd() function.   
        (#) Enable the USART using the USART_Cmd() function.   
        (#) 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.
            
@endverbatim
       
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT 2012 STMicroelectronics</center></h2>
  *
  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
  * You may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *        http://www.st.com/software_license_agreement_liberty_v2
  *
  * Unless required by applicable law or agreed to in writing, software 
  * distributed under the License is distributed on an "AS IS" BASIS, 
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  ******************************************************************************
  */

/* Includes ------------------------------------------------------------------*/
#include "stm32f0xx_usart.h"
#include "stm32f0xx_rcc.h"

/** @addtogroup STM32F0xx_StdPeriph_Driver
  * @{
  */

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

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

/*!< USART CR1 register clear Mask ((~(uint32_t)0xFFFFE6F3)) */
#define CR1_CLEAR_MASK            ((uint32_t)(USART_CR1_M | USART_CR1_PCE | \
                                              USART_CR1_PS | USART_CR1_TE | \
                                              USART_CR1_RE))

/*!< USART CR2 register clock bits clear Mask ((~(uint32_t)0xFFFFF0FF)) */
#define CR2_CLOCK_CLEAR_MASK      ((uint32_t)(USART_CR2_CLKEN | USART_CR2_CPOL | \
                                              USART_CR2_CPHA | USART_CR2_LBCL))

/*!< USART CR3 register clear Mask ((~(uint32_t)0xFFFFFCFF)) */
#define CR3_CLEAR_MASK            ((uint32_t)(USART_CR3_RTSE | USART_CR3_CTSE))

/*!< USART Interrupts mask */
#define IT_MASK                   ((uint32_t)0x000000FF)

/* 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.
        (+) 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 or 2 to select the USART 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);
    }
  }
}

/**
  * @brief  Initializes the USARTx peripheral according to the specified
  *   parameters in the USART_InitStruct .
  * @param  USARTx: where x can be 1 or 2 to select the USART 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 = 0, apbclock = 0;
  uint32_t integerdivider = 0;
  uint32_t fractionaldivider = 0;
  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));
  
  /* Disable USART */
  USARTx->CR1 &= (uint32_t)~((uint32_t)USART_CR1_UE);
  
/*---------------------------- 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 = 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 = 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 = tmpreg;

/*---------------------------- USART BRR Configuration -----------------------*/
  /* Configure the USART Baud Rate -------------------------------------------*/
  RCC_GetClocksFreq(&RCC_ClocksStatus);
  
  if (USARTx == USART1)
  {
    apbclock = RCC_ClocksStatus.USART1CLK_Frequency;
  }
  else
  {
    apbclock = RCC_ClocksStatus.PCLK_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 & CR1_OVER8_Set) == 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 & CR1_OVER8_Set) == 0) */
  {
    tmpreg |= ((((fractionaldivider * 16) + 50) / 100)) & ((uint8_t)0x0F);
  }
 
  /* Write to USART BRR */
  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 or 2 to select the USART peripheral.
  * @param  USART_ClockInitStruct: pointer to a USART_ClockInitTypeDef
  *   structure that contains the configuration information for the specified 
  *   USART peripheral.  
  * @retval None
  */
void USART_ClockInit(USART_TypeDef* USARTx, USART_ClockInitTypeDef* USART_ClockInitStruct)
{
  uint32_t tmpreg = 0;
  /* Check the parameters */