Spi Class Reference

Detailed Description

This file defines the SPI interface for libmraa

    mraa::Spi spi(SPI_PORT);

    while (flag) {
        for (i = 90; i < 130; i++) {
            data[1] = i;
            recv = spi.write(data, 2);
            std::cout << "Writing -%i" << i << std::endl;
            if (recv) {
                std::cout << "RECIVED-%i-%i" << recv[0] << recv[1] << std::endl;
                free(recv);
            }
            usleep(100000);
        }

        for (i = 130; i > 90; i--) {
            data[1] = i;
            if (spi.transfer(data, rxBuf, 2) == mraa::SUCCESS) {
                std::cout << "Writing -%i" << i << std::endl;
                std::cout << "RECIVED-%i-%i" << rxBuf[0] << rxBuf[1] << std::endl;
            }
            usleep(100000);
        }
    }

Public Member Functions
	Spi (int bus)
	Spi (int bus, int cs)
	Spi (void *spi_context)
	~Spi ()
Result	mode (Spi_Mode mode)
Result	frequency (int hz)
int	writeByte (uint8_t data)
int	writeWord (uint16_t data)
uint8_t *	write (uint8_t *txBuf, int length)
uint16_t *	writeWord (uint16_t *txBuf, int length)
Result	transfer (uint8_t *txBuf, uint8_t *rxBuf, int length)
Result	transfer_word (uint16_t *txBuf, uint16_t *rxBuf, int length)
Result	lsbmode (bool lsb)
Result	bitPerWord (unsigned int bits)

Constructor & Destructor Documentation

Spi ( int  bus )

inline

Initialise SPI object using the board mapping to set muxes

Parameters

bus	to use, as listed in the platform definition, normally 0

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Spi ( int  bus, int  cs  )

inline

Initialise SPI object using 'raw' mode. Mraa will go and grab the spidev device lablled /dev/spidev[bus].[cs]

Parameters

bus	to use
cs	to use

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Spi ( void *  spi_context )

inline

Spi Constructor, takes a pointer to a SPI context and initialises the SPI class

Parameters

spi_context

void * to SPI context

~Spi ( )

inline

Closes spi bus

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Member Function Documentation

Result mode ( Spi_Mode  mode )

inline

Set the SPI device mode. see spidev0-3

Parameters

mode	the mode. See Linux spidev doc

Returns

Result of operation

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Result frequency ( int  hz )

inline

Set the SPI device operating clock frequency

Parameters

hz	the frequency to set in hz

Returns

Result of operation

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int writeByte ( uint8_t  data )

inline

Write single byte to the SPI device

Parameters

data	the byte to send

Returns

data received on the miso line or -1 in case of error

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int writeWord ( uint16_t  data )

inline

Write single byte to the SPI device

Parameters

data	the byte to send

Returns

data received on the miso line or -1 in case of error

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uint8_t* write ( uint8_t *  txBuf, int  length  )

inline

Write buffer of bytes to SPI device The pointer return has to be free'd by the caller. It will return a NULL pointer in cases of error

Parameters

txBuf	buffer to send
length	size of buffer to send

Returns

uint8_t* data received on the miso line. Same length as passed in

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uint16_t* writeWord ( uint16_t *  txBuf, int  length  )

inline

Write buffer of bytes to SPI device The pointer return has to be free'd by the caller. It will return a NULL pointer in cases of error

Parameters

txBuf	buffer to send
length	size of buffer (in bytes) to send

Returns

uint8_t* data received on the miso line. Same length as passed in

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Result transfer ( uint8_t *  txBuf, uint8_t *  rxBuf, int  length  )

inline

Transfer data to and from SPI device Receive pointer may be null if return data is not needed.

Parameters

txBuf	buffer to send
rxBuf	buffer to optionally receive data from spi device
length	size of buffer to send

Returns

Result of operation

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Result transfer_word ( uint16_t *  txBuf, uint16_t *  rxBuf, int  length  )

inline

Transfer data to and from SPI device Receive pointer may be null if return data is not needed.

Parameters

txBuf	buffer to send
rxBuf	buffer to optionally receive data from spi device
length	size of buffer to send

Returns

Result of operation

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Result lsbmode ( bool  lsb )

inline

Change the SPI lsb mode

Parameters

lsb	Use least significant bit transmission - 0 for msbi

Returns

Result of operation

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Result bitPerWord ( unsigned int  bits )

inline

Set bits per mode on transaction, default is 8

Parameters

bits	bits per word

Returns

Result of operation

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The documentation for this class was generated from the following file:

• api/mraa/spi.hpp