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/** \addtogroup spi_module Working with SPI
* The SPI driver provides the interface to configure and use the SPI
* peripheral.
*
* The Serial Peripheral Interface (SPI) circuit is a synchronous serial
* data link that provides communication with external devices in Master
* or Slave Mode.
*
* To use the SPI, the user has to follow these few steps:
* -# Enable the SPI pins required by the application (see pio.h).
* -# Configure the SPI using the \ref SPI_Configure(). This enables the
* peripheral clock. The mode register is loaded with the given value.
* -# Configure all the necessary chip selects with \ref SPI_ConfigureNPCS().
* -# Enable the SPI by calling \ref SPI_Enable().
* -# Send/receive data using \ref SPI_Write() and \ref SPI_Read(). Note that
* \ref SPI_Read()
* must be called after \ref SPI_Write() to retrieve the last value read.
* -# Disable the SPI by calling \ref SPI_Disable().
*
* For more accurate information, please look at the SPI section of the
* Datasheet.
*
* Related files :\n
* \ref spi.c\n
* \ref spi.h.\n
*/
/*@{*/
/*@}*/
/**
* \file
*
* Implementation of Serial Peripheral Interface (SPI) controller.
*
*/
/*----------------------------------------------------------------------------
* Headers
*----------------------------------------------------------------------------*/
#include "chip.h"
#include <stdint.h>
/*----------------------------------------------------------------------------
* Exported functions
*----------------------------------------------------------------------------*/
/**
* \brief Enables a SPI peripheral.
*
* \param spi Pointer to an SPI instance.
*/
extern void SPI_Enable(Spi *spi)
{
spi->SPI_CR = SPI_CR_SPIEN;
}
/**
* \brief Disables a SPI peripheral.
*
* \param spi Pointer to an SPI instance.
*/
extern void SPI_Disable(Spi *spi)
{
spi->SPI_CR = SPI_CR_SPIDIS;
}
/**
* \brief Enables one or more interrupt sources of a SPI peripheral.
*
* \param spi Pointer to an SPI instance.
* \param sources Bitwise OR of selected interrupt sources.
*/
extern void SPI_EnableIt(Spi *spi, uint32_t dwSources)
{
spi->SPI_IER = dwSources;
}
/**
* \brief Disables one or more interrupt sources of a SPI peripheral.
*
* \param spi Pointer to an SPI instance.
* \param sources Bitwise OR of selected interrupt sources.
*/
extern void SPI_DisableIt(Spi *spi, uint32_t dwSources)
{
spi->SPI_IDR = dwSources;
}
/**
* \brief Configures a SPI peripheral as specified. The configuration can be
* computed using several macros (see \ref spi_configuration_macros).
*
* \param spi Pointer to an SPI instance.
* \param id Peripheral ID of the SPI.
* \param configuration Value of the SPI configuration register.
*/
extern void SPI_Configure(Spi *spi, uint32_t dwId, uint32_t dwConfiguration)
{
PMC_EnablePeripheral(dwId);
spi->SPI_CR = SPI_CR_SPIDIS;
/* Execute a software reset of the SPI twice */
spi->SPI_CR = SPI_CR_SWRST;
spi->SPI_CR = SPI_CR_SWRST;
spi->SPI_MR = dwConfiguration;
}
/**
* \brief Configures SPI chip select.
*
* \param spi Pointer to an SPI instance.
* \param cS Chip select of NPSCx.
*/
extern void SPI_ChipSelect(Spi *spi, uint8_t cS)
{
spi->SPI_MR |= SPI_MR_PCS_Msk;
spi->SPI_MR &= ~(SPI_MR_PCS (cS));
}
/**
* \brief Configures SPI Mode Register.
*
* \param spi Pointer to an SPI instance.
* \param configuration Value of the SPI mode register.
*/
extern void SPI_SetMode(Spi *spi,
uint32_t dwConfiguration)
{
spi->SPI_MR = dwConfiguration;
}
/**
* \brief Configures SPI to release last used CS line.
*
* \param spi Pointer to an SPI instance.
*/
extern void SPI_ReleaseCS(Spi *spi)
{
spi->SPI_CR = SPI_CR_LASTXFER;
}
/**
* \brief Configures a chip select of a SPI peripheral. The chip select
* configuration is computed using several macros
* (see \ref spi_configuration_macros).
*
* \param spi Pointer to an SPI instance.
* \param npcs Chip select to configure (0, 1, 2 or 3).
* \param configuration Desired chip select configuration.
*/
void SPI_ConfigureNPCS(Spi *spi, uint32_t dwNpcs, uint32_t dwConfiguration)
{
spi->SPI_CSR[dwNpcs] = dwConfiguration;
}
/**
* \brief Configures a chip select active mode of a SPI peripheral.
*
* \param spi Pointer to an SPI instance.
* \param dwNpcs Chip select to configure (0, 1, 2 or 3).
* \param bReleaseOnLast CS controlled by last transfer.
* SPI_ReleaseCS() is used to release CS.
*/
void SPI_ConfigureCSMode(Spi *spi, uint32_t dwNpcs, uint32_t bReleaseOnLast)
{
if (bReleaseOnLast)
spi->SPI_CSR[dwNpcs] |= SPI_CSR_CSAAT;
else
spi->SPI_CSR[dwNpcs] &= ~SPI_CSR_CSAAT;
}
/**
* \brief Get the current status register of the given SPI peripheral.
* \note This resets the internal value of the status register, so further
* read may yield different values.
* \param spi Pointer to a Spi instance.
* \return SPI status register.
*/
extern uint32_t SPI_GetStatus(Spi *spi)
{
return spi->SPI_SR;
}
/**
* \brief Reads and returns the last word of data received by a SPI peripheral.
* This method must be called after a successful SPI_Write call.
*
* \param spi Pointer to an Spi instance.
*
* \return read data.
*/
extern uint32_t SPI_Read(Spi *spi)
{
while ((spi->SPI_SR & SPI_SR_RDRF) == 0);
return spi->SPI_RDR & 0xFFFF;
}
/**
* \brief Sends data through a SPI peripheral. If the SPI is configured to use a
* fixed peripheral select, the npcs value is meaningless. Otherwise,
* it identifies the component which shall be addressed.
*
* \param spi Pointer to an SPI instance.
* \param npcs Chip select of the component to address (0, 1, 2 or 3).
* \param data Word of data to send.
*/
extern void SPI_Write(Spi *spi, uint32_t dwNpcs, uint16_t wData)
{
/* Send data */
while ((spi->SPI_SR & SPI_SR_TXEMPTY) == 0);
spi->SPI_TDR = wData | SPI_PCS(dwNpcs);
while ((spi->SPI_SR & SPI_SR_TDRE) == 0);
}
/**
* \brief Sends last data through a SPI peripheral.
* If the SPI is configured to use a fixed peripheral select, the npcs value is
* meaningless. Otherwise, it identifies the component which shall be addressed.
*
* \param spi Pointer to an SPI instance.
* \param npcs Chip select of the component to address (0, 1, 2 or 3).
* \param data Word of data to send.
*/
extern void SPI_WriteLast(Spi *spi, uint32_t dwNpcs, uint16_t wData)
{
/* Send data */
while ((spi->SPI_SR & SPI_SR_TXEMPTY) == 0);
spi->SPI_TDR = wData | SPI_PCS(dwNpcs) | SPI_TDR_LASTXFER;
while ((spi->SPI_SR & SPI_SR_TDRE) == 0);
}
/**
* \brief Check if SPI transfer finish.
*
* \param spi Pointer to an SPI instance.
*
* \return Returns 1 if there is no pending write operation on the SPI;
* otherwise returns 0.
*/
extern uint32_t SPI_IsFinished(Spi *spi)
{
return ((spi->SPI_SR & SPI_SR_TXEMPTY) != 0);
}
