API Description

An i2c context represents a master on an i2c bus and that context can communicate to multiple i2c slaves by configuring the address. It is considered best practice to make sure the address is correct before doing any calls on i2c, in case another application or even thread changed the addres on that bus. Multiple instances of the same bus can exist.

    mraa_i2c_context i2c;
    i2c = mraa_i2c_init(0);
    mraa_i2c_address(i2c, HMC5883L_I2C_ADDR);
    rx_tx_buf[0] = HMC5883L_CONF_REG_B;
    rx_tx_buf[1] = GA_1_3_REG;
    mraa_i2c_write(i2c, rx_tx_buf, 2);

Go to the source code of this file.

Functions
mraa_i2c_context	mraa_i2c_init (int bus)

mraa_i2c_context	mraa_i2c_init_raw (unsigned int bus)

mraa_result_t	mraa_i2c_frequency (mraa_i2c_context dev, mraa_i2c_mode_t mode)

int	mraa_i2c_read (mraa_i2c_context dev, uint8_t *data, int length)

uint8_t	mraa_i2c_read_byte (mraa_i2c_context dev)

uint8_t	mraa_i2c_read_byte_data (mraa_i2c_context dev, const uint8_t command)

uint16_t	mraa_i2c_read_word_data (mraa_i2c_context dev, const uint8_t command)

mraa_result_t	mraa_i2c_write (mraa_i2c_context dev, const uint8_t *data, int length)

mraa_result_t	mraa_i2c_write_byte (mraa_i2c_context dev, const uint8_t data)

mraa_result_t	mraa_i2c_write_byte_data (mraa_i2c_context dev, const uint8_t data, const uint8_t command)

mraa_result_t	mraa_i2c_write_word_data (mraa_i2c_context dev, const uint16_t data, const uint8_t command)

mraa_result_t	mraa_i2c_address (mraa_i2c_context dev, uint8_t address)

mraa_result_t	mraa_i2c_stop (mraa_i2c_context dev)

Typedefs
typedef struct _i2c *	mraa_i2c_context

Function Documentation

mraa_i2c_context mraa_i2c_init ( int bus )

Initialise i2c context, using board defintions

Parameters

bus	i2c bus to use

Returns: i2c context or NULL

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mraa_i2c_context mraa_i2c_init_raw ( unsigned int bus )

Initialise i2c context, passing in the i2c bus to use.

Parameters

bus	The i2c bus to use i.e. /dev/i2c-2 would be "2"

Returns: i2c context or NULL

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mraa_result_t mraa_i2c_frequency	(	mraa_i2c_context	dev,
		mraa_i2c_mode_t	mode
	)

Sets the frequency of the i2c context. Most platforms do not support this.

Parameters

dev	The i2c context
mode	The bus mode

Returns: Result of operation

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int mraa_i2c_read	(	mraa_i2c_context	dev,
		uint8_t *	data,
		int	length
	)

Simple bulk read from an i2c context, this will always begin with the i2c offset 0x0

Parameters

dev	The i2c context
data	pointer to the byte array to read data in to
length	max number of bytes to read

Returns: length of the read in bytes or 0

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uint8_t mraa_i2c_read_byte ( mraa_i2c_context dev )

Simple read for a single byte from the i2c context, this will always begin with the i2c offset 0x0

Parameters

dev	The i2c context

Returns: The result of the read or -1 if failed

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uint8_t mraa_i2c_read_byte_data	(	mraa_i2c_context	dev,
		const uint8_t	command
	)

Read a single byte from i2c context, from designated register

Parameters

dev	The i2c context
command	The register

Returns: The result of the read or -1 if failed

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uint16_t mraa_i2c_read_word_data	(	mraa_i2c_context	dev,
		const uint8_t	command
	)

Read a single word from i2c context, from designated register

Parameters

dev	The i2c context
command	The register

Returns: The result of the read or -1 if failed

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mraa_result_t mraa_i2c_write	(	mraa_i2c_context	dev,
		const uint8_t *	data,
		int	length
	)

Write length bytes to the bus, the first byte in the array is the command/register to write

Parameters

dev	The i2c context
data	pointer to the byte array to be written
length	the number of bytes to transmit

Returns: Result of operation

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mraa_result_t mraa_i2c_write_byte	(	mraa_i2c_context	dev,
		const uint8_t	data
	)

Write a single byte to an i2c context, always at offset 0x0

Parameters

dev	The i2c context
data	The byte to write

Returns: Result of operation

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mraa_result_t mraa_i2c_write_byte_data	(	mraa_i2c_context	dev,
		const uint8_t	data,
		const uint8_t	command
	)

Write a single byte to an i2c context

Parameters

dev	The i2c context
data	The byte to write
command	The register

Returns: Result of operation

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mraa_result_t mraa_i2c_write_word_data	(	mraa_i2c_context	dev,
		const uint16_t	data,
		const uint8_t	command
	)

Write a single word to an i2c context

Parameters

dev	The i2c context
data	The word to write
command	The register

Returns: Result of operation

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mraa_result_t mraa_i2c_address	(	mraa_i2c_context	dev,
		uint8_t	address
	)

Sets the i2c context address.

Parameters

dev	The i2c context
address	The address to set for the slave (ignoring the least signifcant bit). If set to 0, the slave will only respond to the general call address.