SPI

SPI (Serial Peripheral Interface) API for Soletta. More...

Data Structures
struct	sol_spi_config
	SPI configuration struct. More...

Macros
#define	SOL_SPI_DATA_BITS_DEFAULT   8
	Default value for bits per word when using SPI. More...

Typedefs
typedef struct sol_spi	sol_spi
	A handle to a SPI bus. More...
typedef struct sol_spi_config	sol_spi_config
	SPI configuration struct. More...

Enumerations
enum	sol_spi_mode { SOL_SPI_MODE_0 = 0, SOL_SPI_MODE_1, SOL_SPI_MODE_2, SOL_SPI_MODE_3 }
	SPI Transfer Modes. More...

Functions
void	sol_spi_close (struct sol_spi *spi)
	Close an SPI bus. More...
enum sol_spi_mode	sol_spi_mode_from_str (const char *spi_mode)
	Converts a string SPI mode name to sol_spi_mode. More...
const char *	sol_spi_mode_to_str (enum sol_spi_mode spi_mode)
	Converts sol_spi_mode to a string name. More...
struct sol_spi *	sol_spi_open (unsigned int bus, const struct sol_spi_config *config)
	Open an SPI bus. More...
int	sol_spi_transfer (struct sol_spi *spi, const uint8_t *tx, uint8_t *rx, size_t count, void(*transfer_cb)(void *cb_data, struct sol_spi *spi, const uint8_t *tx, uint8_t *rx, ssize_t status), const void *cb_data)
	Perform a SPI asynchronous transfer. More...

Detailed Description

SPI (Serial Peripheral Interface) API for Soletta.

Macro Definition Documentation

#define SOL_SPI_DATA_BITS_DEFAULT   8

Default value for bits per word when using SPI.

Typedef Documentation

sol_spi

A handle to a SPI bus.

See Also

sol_spi_open()

sol_spi_close()

sol_spi_transfer()

typedef struct sol_spi_config sol_spi_config

SPI configuration struct.

This struct is used to configure an SPI bus during its creation.

See Also

sol_spi_open()

Enumeration Type Documentation

enum sol_spi_mode

SPI Transfer Modes.

It may enable and disable clock polarity (cpol) and clock phase (cpha) to define a clock format to be used by the SPI bus.

Depending on CPOL parameter, SPI clock may be inverted or non-inverted.

CPHA parameter is used to shift the sampling phase. If CPHA=0 the data are sampled on the leading (first) clock edge.

If CPHA=1 the data are sampled on the trailing (second) clock edge, regardless of whether that clock edge is rising or falling.

Enumerator
SOL_SPI_MODE_0
SOL_SPI_MODE_1	CPOL = 0 and CPHA = 0.
SOL_SPI_MODE_2	CPOL = 0 and CPHA = 1.
SOL_SPI_MODE_3	CPOL = 1 and CPHA = 0. CPOL = 1 and CPHA = 1

Function Documentation

void sol_spi_close

(

struct sol_spi *

spi

)

Close an SPI bus.

Parameters

spi	The SPI bus handle

enum sol_spi_mode sol_spi_mode_from_str

(

const char *

spi_mode

)

Converts a string SPI mode name to sol_spi_mode.

This function converts a string SPI mode name to enumeration sol_spi_mode.

See Also

sol_spi_mode_to_str().

Parameters

spi_mode

Valid values are "mode0", "mode1", "mode2", "mode3".

Returns

enumeration sol_spi_mode

const char* sol_spi_mode_to_str

(

enum sol_spi_mode

spi_mode

)

Converts sol_spi_mode to a string name.

This function converts sol_spi_mode enumeration to a string SPI mode name.

See Also

sol_spi_mode_from_str().

Parameters

spi_mode

sol_spi_mode

Returns

String representation of the sol_spi_mode

struct sol_spi* sol_spi_open	(	unsigned int	bus,
		const struct sol_spi_config *	config
	)

Open an SPI bus.

Parameters

bus	The SPI bus number to open
config	The SPI bus configuration

Returns

A new SPI bus handle

Note

For now it only supports one user of the bus at time, 2 or mode devices with different chip select on the same bus will cause concurrency errors.

int sol_spi_transfer	(	struct sol_spi *	spi,
		const uint8_t *	tx,
		uint8_t *	rx,
		size_t	count,
		void(*)(void *cb_data, struct sol_spi *spi, const uint8_t *tx, uint8_t *rx, ssize_t status)	transfer_cb,
		const void *	cb_data
	)

Perform a SPI asynchronous transfer.

Parameters

spi	The SPI bus handle
tx	The output buffer
rx	The input buffer
count	number of bytes to be transfer
transfer_cb	callback to be called when transmission finish, in case of success the status parameters on callback should be the same value as count, otherwise a error happen.
cb_data	user data, first parameter of transfer_cb

Returns

0 if the transfer started, -EBUSY if the bus is busy or -errno on error.

As SPI works in full-duplex, data are going in and out at same time, so both buffers must have the same count size. Caller should guarantee that both buffers will not be freed until callback is called. Also there is no transfer queue, calling this function when there is transfer happening would return false.