FreeRTOS/Demo/CORTEX_A5_SAMA5D3x_Xplained_IAR/AtmelFiles/libchip_sama5d3x/source/usart.c

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/** \addtogroup usart_module Working with USART
 * The USART driver provides the interface to configure and use the USART peripheral.\n
 *
 * The USART supports several kinds of comminication modes such as full-duplex asynchronous/
 * synchronous serial commnunication,RS485 with driver control signal,ISO7816,SPI and Test modes.
 *
 * To start a USART transfer with \ref dmad_module "DMA" support, the user could follow these steps:
 * <ul>
 * <li> Configure USART with expected mode and baudrate(see \ref USART_Configure), which could be done by:
 * -# Resetting and disabling transmitter and receiver by setting US_CR(Control Register). </li>
 * -# Conifguring the USART in a specific mode by setting USART_MODE bits in US_MR(Mode Register) </li>
 * -# Setting baudrate which is different from mode to mode.
   </li>
 * <li> Enable transmitter or receiver respectively by set US_CR_TXEN or US_CR_RXEN in US_CR.</li>
 * <li> Read from or write to the peripheral with  \ref dmad_module </li> 
 * </ul>
 *
 * For more accurate information, please look at the USART section of the
 * Datasheet.
 *
 * Related files :\n
 * \ref usart.c\n
 * \ref usart.h\n
*/



/**
 * \file
 *
 * Implementation of USART (Universal Synchronous Asynchronous Receiver Transmitter)
 * controller.
 *
 */
/*------------------------------------------------------------------------------
 *         Headers
 *------------------------------------------------------------------------------*/
#include "chip.h"

#include <assert.h>
#include <string.h>

/*------------------------------------------------------------------------------
 *         Exported functions
 *------------------------------------------------------------------------------*/

/**
 * \brief Configures an USART peripheral with the specified parameters.
 *
 *
 *  \param usart  Pointer to the USART peripheral to configure.
 *  \param mode  Desired value for the USART mode register (see the datasheet).
 *  \param baudrate  Baudrate at which the USART should operate (in Hz).
 *  \param masterClock  Frequency of the system master clock (in Hz).
 */
void USART_Configure(Usart *usart,
                     uint32_t mode,
                     uint32_t baudrate,
                     uint32_t masterClock)
{
    uint32_t maxClock;
    uint32_t id = ID_USART0;
    maxClock = masterClock;
    /* Reset and disable receiver & transmitter*/
    usart->US_CR = US_CR_RSTRX | US_CR_RSTTX
                   | US_CR_RXDIS | US_CR_TXDIS;
    if ((uint32_t)usart == (uint32_t)USART0) id = ID_USART0;
       else if ((uint32_t)usart == (uint32_t)USART1) id = ID_USART1;
              else if ((uint32_t)usart == (uint32_t)USART2) id = ID_USART2;
                     else if ((uint32_t)usart == (uint32_t)USART3) id = ID_USART3;
    /* Configure mode*/
    usart->US_MR = mode;
    maxClock = PMC_SetPeriMaxClock(id, masterClock);
    /* Configure baudrate*/
    /* Asynchronous, no oversampling*/
    if (((mode & US_MR_SYNC) == 0)
        && ((mode & US_MR_OVER) == 0))
    {
        usart->US_BRGR = (maxClock / baudrate) / 16;
    }
    if( ((mode & US_MR_USART_MODE_SPI_MASTER) == US_MR_USART_MODE_SPI_MASTER)
     || ((mode & US_MR_SYNC) == US_MR_SYNC))
    {
        if( (mode & US_MR_USCLKS_Msk) == US_MR_USCLKS_MCK)
        {
            usart->US_BRGR = maxClock / baudrate;
        }
        else
        {
            if ( (mode & US_MR_USCLKS_DIV) == US_MR_USCLKS_DIV)
            {
                usart->US_BRGR = maxClock / baudrate / 8;
            }
        }
    }
    /* TODO other modes*/
}
/**
 * \brief Enables or disables the transmitter of an USART peripheral.
 *
 *
 * \param usart  Pointer to an USART peripheral
 * \param enabled  If true, the transmitter is enabled; otherwise it is
 *                disabled.
 */
void USART_SetTransmitterEnabled(Usart *usart, uint8_t enabled)
{
    if (enabled) {

        usart->US_CR = US_CR_TXEN;
    }
    else {

        usart->US_CR = US_CR_TXDIS;
    }
}

/**
 * \brief Enables or disables the receiver of an USART peripheral
 *
 *
 * \param usart  Pointer to an USART peripheral
 * \param enabled  If true, the receiver is enabled; otherwise it is disabled.
 */
void USART_SetReceiverEnabled(Usart *usart, uint8_t enabled)
{
    if (enabled) {

        usart->US_CR = US_CR_RXEN;
    }
    else {

        usart->US_CR = US_CR_RXDIS;
    }
}

/**
 * \brief Enables or disables the Request To Send (RTS) of an USART peripheral
 *
 *
 * \param usart  Pointer to an USART peripheral
 * \param enabled  If true, the RTS is enabled (0); otherwise it is disabled.
 */
void USART_SetRTSEnabled( Usart *usart, uint8_t enabled)
{
    if (enabled) {
    
        usart->US_CR = US_CR_RTSEN;
    }
    else {
        
        usart->US_CR = US_CR_RTSDIS;
    }
}

/**
 * \brief Sends one packet of data through the specified USART peripheral. This
 * function operates synchronously, so it only returns when the data has been
 * actually sent.
 *
 *
 * \param usart  Pointer to an USART peripheral.
 * \param data  Data to send including 9nth bit and sync field if necessary (in
 *        the same format as the US_THR register in the datasheet).
 * \param timeOut  Time out value (0 = no timeout).
 */
void USART_Write( Usart *usart, uint16_t data, volatile uint32_t timeOut)
{
    if (timeOut == 0) {

        while ((usart->US_CSR & US_CSR_TXEMPTY) == 0);
    }
    else {

        while ((usart->US_CSR & US_CSR_TXEMPTY) == 0) {

            if (timeOut == 0) {

                TRACE_ERROR("USART_Write: Timed out.\n\r");
                return;
            }
            timeOut--;
        }
    }

    usart->US_THR = data;
}


/**
 * \brief  Reads and return a packet of data on the specified USART peripheral. This
 * function operates asynchronously, so it waits until some data has been
 * received.
 *
 * \param usart  Pointer to an USART peripheral.
 * \param timeOut  Time out value (0 -> no timeout).
 */
uint16_t USART_Read( Usart *usart, volatile uint32_t timeOut)
{
    if (timeOut == 0) {

        while ((usart->US_CSR & US_CSR_RXRDY) == 0);
    }
    else {

        while ((usart->US_CSR & US_CSR_RXRDY) == 0) {

            if (timeOut == 0) {

                TRACE_ERROR( "USART_Read: Timed out.\n\r" ) ;
                return 0;
            }
            timeOut--;
        }
    }

    return usart->US_RHR;
}

/**
 * \brief  Returns 1 if some data has been received and can be read from an USART;
 * otherwise returns 0.
 *
 * \param usart  Pointer to an Usart instance.
 */
uint8_t USART_IsDataAvailable(Usart *usart)
{
    if ((usart->US_CSR & US_CSR_RXRDY) != 0) {

        return 1;
    }
    else {

        return 0;
    }
}

/**
 * \brief  Sets the filter value for the IRDA demodulator.
 *
 * \param pUsart  Pointer to an Usart instance.
 * \param filter  Filter value.
 */
void USART_SetIrdaFilter(Usart *pUsart, uint8_t filter)
{
    assert( pUsart != NULL ) ;

    pUsart->US_IF = filter;
}

/**
 * \brief  Sends one packet of data through the specified USART peripheral. This
 * function operates synchronously, so it only returns when the data has been
 * actually sent.
 *
 * \param usart  Pointer to an USART peripheral.
 * \param c  Character to send
 */
void USART_PutChar( Usart *usart, uint8_t c)
{
    /* Wait for the transmitter to be ready*/
    while ((usart->US_CSR & US_CSR_TXEMPTY) == 0);

    /* Send character*/
    usart->US_THR = c;

    /* Wait for the transfer to complete*/
    while ((usart->US_CSR & US_CSR_TXEMPTY) == 0);
}

/**
 * \brief   Return 1 if a character can be read in USART
 * \param usart  Pointer to an USART peripheral.
 */
uint32_t USART_IsRxReady(Usart *usart)
{
    return (usart->US_CSR & US_CSR_RXRDY);
}

/**
 * \brief   Get present status
 * \param usart  Pointer to an USART peripheral.
 */
uint32_t USART_GetStatus(Usart *usart)
{
    return usart->US_CSR;
}

/**
 * \brief   Enable interrupt
 * \param usart  Pointer to an USART peripheral.
 * \param mode  Interrupt mode.
 */
void USART_EnableIt(Usart *usart,uint32_t mode)
{
    usart->US_IER = mode;
}

/**
 * \brief   Disable interrupt
 * \param usart  Pointer to an USART peripheral.
 * \param mode  Interrupt mode.
 */
void USART_DisableIt(Usart *usart,uint32_t mode)
{
    usart->US_IDR = mode;
}

/**
 * \brief   Return interrupt mask
 * \param usart  Pointer to an USART peripheral.
 */
uint32_t USART_GetItMask(Usart *usart)
{
    return usart->US_IMR;
}

/**
 * \brief  Reads and returns a character from the USART.
 *
 * \note This function is synchronous (i.e. uses polling).
 * \param usart  Pointer to an USART peripheral.
 * \return Character received.
 */
uint8_t USART_GetChar(Usart *usart)
{
    while ((usart->US_CSR & US_CSR_RXRDY) == 0);
    return usart->US_RHR;
}