FreeRTOS/Demo/CORTEX_M7_SAMV71_Xplained_AtmelStudio/libchip_samv7/source/twi.c

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 *
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/** \addtogroup twi_module Working with TWI
 *  \ingroup peripherals_module
 * The TWI driver provides the interface to configure and use the TWI
 * peripheral.
 *
 * \section Usage
 * <ul>
 * <li> Configures a TWI peripheral to operate in master mode, at the given
 * frequency (in Hz) using TWI_Configure(). </li>
 * <li> Sends a STOP condition on the TWI using TWI_Stop().</li>
 * <li> Starts a read operation on the TWI bus with the specified slave using
 * TWI_StartRead(). Data must then be read using TWI_ReadByte() whenever
 * a byte is available (poll using TWI_ByteReceived()).</li>
 * <li> Starts a write operation on the TWI to access the selected slave using
 * TWI_StartWrite(). A byte of data must be provided to start the write;
 * other bytes are written next.</li>
 * <li> Sends a byte of data to one of the TWI slaves on the bus using 
 * TWI_WriteByte().
 * This function must be called once before TWI_StartWrite() with the first 
 * byte of data
 * to send, then it shall be called repeatedly after that to send the 
 * remaining bytes.</li>
 * <li> Check if a byte has been received and can be read on the given TWI
 * peripheral using TWI_ByteReceived().<
 * Check if a byte has been sent using TWI_ByteSent().</li>
 * <li> Check if the current transmission is complete (the STOP has been sent)
 * using TWI_TransferComplete().</li>
 * <li> Enables & disable the selected interrupts sources on a TWI peripheral
 * using TWI_EnableIt() and TWI_DisableIt().</li>
 * <li> Get current status register of the given TWI peripheral using
 * TWI_GetStatus(). Get current status register of the given TWI peripheral, but
 * masking interrupt sources which are not currently enabled using
 * TWI_GetMaskedStatus().</li>
 * </ul>
 * For more accurate information, please look at the TWI section of the
 * Datasheet.
 *
 * Related files :\n
 * \ref twi.c\n
 * \ref twi.h.\n
 */
/*@{*/
/*@}*/

/**
 * \file
 *
 * Implementation of Two Wire Interface (TWI).
 *
 */

/*----------------------------------------------------------------------------
 *        Headers
 *----------------------------------------------------------------------------*/

#include "chip.h"

#include <assert.h>

#define TWIHS_IT    ( TWIHS_IER_TXCOMP | TWIHS_IER_TXCOMP | TWIHS_IER_RXRDY \
					| TWIHS_IER_TXRDY | TWIHS_IER_SVACC | TWIHS_IER_GACC | \
					  TWIHS_IER_OVRE | TWIHS_IER_UNRE | TWIHS_IER_NACK | \
					  TWIHS_IER_ARBLST | TWIHS_IER_SCL_WS | TWIHS_IER_EOSACC | \
					  TWIHS_IER_MCACK | TWIHS_IER_TOUT | TWIHS_IER_PECERR |\
					  TWIHS_IER_SMBDAM | TWIHS_IER_SMBHHM)
					  
/*----------------------------------------------------------------------------
 *        Exported functions
 *----------------------------------------------------------------------------*/

/**
 * \brief Configures a TWI peripheral to operate in master mode, at the given
 * frequency (in Hz). The duty cycle of the TWI clock is set to 50%.
 * \param pTwi  Pointer to an Twihs instance.
 * \param twck  Desired TWI clock frequency.
 * \param mck  Master clock frequency.
 */
void TWI_ConfigureMaster( Twihs *pTwi, uint32_t dwTwCk, uint32_t dwMCk )
{
	uint32_t dwCkDiv = 0 ;
	uint32_t dwClDiv ;
	uint32_t dwOk = 0 ;

	TRACE_DEBUG( "TWI_ConfigureMaster()\n\r" ) ;
	assert( pTwi ) ;

	/* SVEN: TWI Slave Mode Enabled */
	pTwi->TWIHS_CR = TWIHS_CR_SVEN ;
	/* Reset the TWI */
	pTwi->TWIHS_CR = TWIHS_CR_SWRST ;
	pTwi->TWIHS_RHR ;

	/* TWI Slave Mode Disabled, TWI Master Mode Disabled. */
	pTwi->TWIHS_CR = TWIHS_CR_SVDIS ;
	pTwi->TWIHS_CR = TWIHS_CR_MSDIS ;

	/* Set master mode */
	pTwi->TWIHS_CR = TWIHS_CR_MSEN ;

	/* Configure clock */
	while ( !dwOk ) {
		dwClDiv = ((dwMCk / (2 * dwTwCk)) - 4) / (1<<dwCkDiv) ;

		if ( dwClDiv <= 255 ) {
			dwOk = 1 ;
		} else {
			dwCkDiv++ ;
		}
	}
	assert( dwCkDiv < 8 ) ;
	TRACE_DEBUG( "Using CKDIV = %u and CLDIV/CHDIV = %u\n\r", dwCkDiv, dwClDiv ) ;

	pTwi->TWIHS_CWGR = 0 ;
	pTwi->TWIHS_CWGR = (dwCkDiv << 16) | (dwClDiv << 8) | dwClDiv ;
}

/**
 * \brief Configures a TWI peripheral to operate in slave mode.
 * \param pTwi  Pointer to an Twihs instance.
 * \param slaveAddress Slave address.
 */
void TWI_ConfigureSlave(Twihs *pTwi, uint8_t slaveAddress)
{
	uint32_t i;

	/* TWI software reset */
	pTwi->TWIHS_CR = TWIHS_CR_SWRST;
	pTwi->TWIHS_RHR;

	/* Wait at least 10 ms */
	for (i=0; i < 1000000; i++);

	/* TWI Slave Mode Disabled, TWI Master Mode Disabled*/
	pTwi->TWIHS_CR = TWIHS_CR_SVDIS | TWIHS_CR_MSDIS;

	/* Configure slave address. */
	pTwi->TWIHS_SMR = 0;
	pTwi->TWIHS_SMR = TWIHS_SMR_SADR(slaveAddress);

	/* SVEN: TWI Slave Mode Enabled */
	pTwi->TWIHS_CR = TWIHS_CR_SVEN;

	/* Wait at least 10 ms */
	for (i=0; i < 1000000; i++);
	assert( (pTwi->TWIHS_CR & TWIHS_CR_SVDIS)!= TWIHS_CR_SVDIS ) ;
}

/**
 * \brief Sends a STOP condition on the TWI.
 * \param pTwi  Pointer to an Twihs instance.
 */
void TWI_Stop( Twihs *pTwi )
{
	assert( pTwi != NULL ) ;

	pTwi->TWIHS_CR = TWIHS_CR_STOP;
}

/**
 * \brief Starts a read operation on the TWI bus with the specified slave, it 
 * returns immediately. Data must then be read using TWI_ReadByte() whenever a
 * byte is available (poll using TWI_ByteReceived()).
 * \param pTwi  Pointer to an Twihs instance.
 * \param address  Slave address on the bus.
 * \param iaddress  Optional internal address bytes.
 * \param isize  Number of internal address bytes.
 */
void TWI_StartRead(
		Twihs *pTwi,
		uint8_t address,
		uint32_t iaddress,
		uint8_t isize)
{
	assert( pTwi != NULL ) ;
	assert( (address & 0x80) == 0 ) ;
	assert( (iaddress & 0xFF000000) == 0 ) ;
	assert( isize < 4 ) ;

	/* Set slave address and number of internal address bytes. */
	pTwi->TWIHS_MMR = 0;
	pTwi->TWIHS_MMR = (isize << 8) | TWIHS_MMR_MREAD | (address << 16);

	/* Set internal address bytes */
	pTwi->TWIHS_IADR = 0;
	pTwi->TWIHS_IADR = iaddress;

	/* Send START condition */
	pTwi->TWIHS_CR = TWIHS_CR_START;
}

/**
 * \brief Reads a byte from the TWI bus. The read operation must have been started
 * using TWI_StartRead() and a byte must be available (check with TWI_ByteReceived()).
 * \param pTwi  Pointer to an Twihs instance.
 * \return byte read.
 */
uint8_t TWI_ReadByte(Twihs *pTwi)
{
	assert( pTwi != NULL ) ;

	return pTwi->TWIHS_RHR;
}

/**
 * \brief Sends a byte of data to one of the TWI slaves on the bus.
 * \note This function must be called once before TWI_StartWrite() with
 * the first byte of data  to send, then it shall be called repeatedly
 * after that to send the remaining bytes.
 * \param pTwi  Pointer to an Twihs instance.
 * \param byte  Byte to send.
 */
void TWI_WriteByte(Twihs *pTwi, uint8_t byte)
{
	assert( pTwi != NULL ) ;

	pTwi->TWIHS_THR = byte;
}

/**
 * \brief Starts a write operation on the TWI to access the selected slave, then
 *  returns immediately. A byte of data must be provided to start the write;
 * other bytes are written next.
 * after that to send the remaining bytes.
 * \param pTwi  Pointer to an Twihs instance.
 * \param address  Address of slave to acccess on the bus.
 * \param iaddress  Optional slave internal address.
 * \param isize  Number of internal address bytes.
 * \param byte  First byte to send.
 */
void TWI_StartWrite(
		Twihs *pTwi,
		uint8_t address,
		uint32_t iaddress,
		uint8_t isize,
		uint8_t byte)
{
	assert( pTwi != NULL ) ;
	assert( (address & 0x80) == 0 ) ;
	assert( (iaddress & 0xFF000000) == 0 ) ;
	assert( isize < 4 ) ;

	/* Set slave address and number of internal address bytes. */
	pTwi->TWIHS_MMR = 0;
	pTwi->TWIHS_MMR = (isize << 8) | (address << 16);

	/* Set internal address bytes. */
	pTwi->TWIHS_IADR = 0;
	pTwi->TWIHS_IADR = iaddress;

	/* Write first byte to send.*/
	TWI_WriteByte(pTwi, byte);
}

/**
 * \brief Check if a byte have been received from TWI.
 * \param pTwi  Pointer to an Twihs instance.
 * \return 1 if a byte has been received and can be read on the given TWI
 * peripheral; otherwise, returns 0. This function resets the status register.
 */
uint8_t TWI_ByteReceived(Twihs *pTwi)
{
	return ((pTwi->TWIHS_SR & TWIHS_SR_RXRDY) == TWIHS_SR_RXRDY);
}

/**
 * \brief Check if a byte have been sent to TWI.
 * \param pTwi  Pointer to an Twihs instance.
 * \return 1 if a byte has been sent  so another one can be stored for
 * transmission; otherwise returns 0. This function clears the status register.
 */
uint8_t TWI_ByteSent(Twihs *pTwi)
{
	return ((pTwi->TWIHS_SR & TWIHS_SR_TXRDY) == TWIHS_SR_TXRDY);
}

/**
 * \brief Check if current transmission is completed.
 * \param pTwi  Pointer to an Twihs instance.
 * \return  1 if the current transmission is complete (the STOP has been sent);
 * otherwise returns 0.
 */
uint8_t TWI_TransferComplete(Twihs *pTwi)
{
	return ((pTwi->TWIHS_SR & TWIHS_SR_TXCOMP) == TWIHS_SR_TXCOMP);
}

/**
 * \brief Enables the selected interrupts sources on a TWI peripheral.
 * \param pTwi  Pointer to an Twihs instance.
 * \param sources  Bitwise OR of selected interrupt sources.
 */
void TWI_EnableIt(Twihs *pTwi, uint32_t sources)
{
	assert( pTwi != NULL ) ;
	assert( (sources & TWIHS_IT) ) ;

	pTwi->TWIHS_IER = sources;
}

/**
 * \brief Disables the selected interrupts sources on a TWI peripheral.
 * \param pTwi  Pointer to an Twihs instance.
 * \param sources  Bitwise OR of selected interrupt sources.
 */
void TWI_DisableIt(Twihs *pTwi, uint32_t sources)
{
	assert( pTwi != NULL ) ;
	assert(sources & TWIHS_IT ) ;

	pTwi->TWIHS_IDR = sources;
}

/**
 * \brief Get the current status register of the given TWI peripheral.
 * \note This resets the internal value of the status register, so further
 * read may yield different values.
 * \param pTwi  Pointer to an Twihs instance.
 * \return  TWI status register.
 */
uint32_t TWI_GetStatus(Twihs *pTwi)
{
	assert( pTwi != NULL ) ;

	return pTwi->TWIHS_SR;
}

/**
 * \brief Returns the current status register of the given TWI peripheral, but
 * masking interrupt sources which are not currently enabled.
 * \note This resets the internal value of the status register, so further
 * read may yield different values.
 * \param pTwi  Pointer to an Twihs instance.
 */
uint32_t TWI_GetMaskedStatus(Twihs *pTwi)
{
	uint32_t status;

	assert( pTwi != NULL ) ;

	status = pTwi->TWIHS_SR;
	status &= pTwi->TWIHS_IMR;

	return status;
}

/**
 * \brief  Sends a STOP condition. STOP Condition is sent just after completing
 *  the current byte transmission in master read mode.
 * \param pTwi  Pointer to an Twihs instance.
 */
void TWI_SendSTOPCondition(Twihs *pTwi)
{
	assert( pTwi != NULL ) ;

	pTwi->TWIHS_CR |= TWIHS_CR_STOP;
}