Channel

Data Structures
struct	iio_channel
	Represents an input or output channel of a device. More...

Functions
__api __pure const struct iio_device *	iio_channel_get_device (const struct iio_channel *chn)
	Retrieve a pointer to the iio_device structure. More...
__api __pure const char *	iio_channel_get_id (const struct iio_channel *chn)
	Retrieve the channel ID (e.g. voltage0) More...
__api __pure const char *	iio_channel_get_name (const struct iio_channel *chn)
	Retrieve the channel name (e.g. vccint) More...
__api __pure bool	iio_channel_is_output (const struct iio_channel *chn)
	Return True if the given channel is an output channel. More...
__api __pure bool	iio_channel_is_scan_element (const struct iio_channel *chn)
	Return True if the given channel is a scan element. More...
__api __pure unsigned int	iio_channel_get_attrs_count (const struct iio_channel *chn)
	Enumerate the channel-specific attributes of the given channel. More...
__api __pure const char *	iio_channel_get_attr (const struct iio_channel *chn, unsigned int index)
	Get the channel-specific attribute present at the given index. More...
__api __pure const char *	iio_channel_find_attr (const struct iio_channel *chn, const char *name)
	Try to find a channel-specific attribute by its name. More...
__api __pure const char *	iio_channel_attr_get_filename (const struct iio_channel *chn, const char *attr)
	Retrieve the filename of an attribute. More...
__api ssize_t	iio_channel_attr_read (const struct iio_channel *chn, const char *attr, char *dst, size_t len)
	Read the content of the given channel-specific attribute. More...
__api int	iio_channel_attr_read_all (struct iio_channel *chn, int(*cb)(struct iio_channel *chn, const char *attr, const char *val, size_t len, void *d), void *data)
	Read the content of all channel-specific attributes. More...
__api int	iio_channel_attr_read_bool (const struct iio_channel *chn, const char *attr, bool *val)
	Read the content of the given channel-specific attribute. More...
__api int	iio_channel_attr_read_longlong (const struct iio_channel *chn, const char *attr, long long *val)
	Read the content of the given channel-specific attribute. More...
__api int	iio_channel_attr_read_double (const struct iio_channel *chn, const char *attr, double *val)
	Read the content of the given channel-specific attribute. More...
__api ssize_t	iio_channel_attr_write (const struct iio_channel *chn, const char *attr, const char *src)
	Set the value of the given channel-specific attribute. More...
__api ssize_t	iio_channel_attr_write_raw (const struct iio_channel *chn, const char *attr, const void *src, size_t len)
	Set the value of the given channel-specific attribute. More...
__api int	iio_channel_attr_write_all (struct iio_channel *chn, ssize_t(*cb)(struct iio_channel *chn, const char *attr, void *buf, size_t len, void *d), void *data)
	Set the values of all channel-specific attributes. More...
__api int	iio_channel_attr_write_bool (const struct iio_channel *chn, const char *attr, bool val)
	Set the value of the given channel-specific attribute. More...
__api int	iio_channel_attr_write_longlong (const struct iio_channel *chn, const char *attr, long long val)
	Set the value of the given channel-specific attribute. More...
__api int	iio_channel_attr_write_double (const struct iio_channel *chn, const char *attr, double val)
	Set the value of the given channel-specific attribute. More...
__api void	iio_channel_enable (struct iio_channel *chn)
	Enable the given channel. More...
__api void	iio_channel_disable (struct iio_channel *chn)
	Disable the given channel. More...
__api bool	iio_channel_is_enabled (const struct iio_channel *chn)
	Returns True if the channel is enabled. More...
__api size_t	iio_channel_read_raw (const struct iio_channel *chn, struct iio_buffer *buffer, void *dst, size_t len)
__api size_t	iio_channel_read (const struct iio_channel *chn, struct iio_buffer *buffer, void *dst, size_t len)
__api size_t	iio_channel_write_raw (const struct iio_channel *chn, struct iio_buffer *buffer, const void *src, size_t len)
__api size_t	iio_channel_write (const struct iio_channel *chn, struct iio_buffer *buffer, const void *src, size_t len)
__api void	iio_channel_set_data (struct iio_channel *chn, void *data)
	Associate a pointer to an iio_channel structure. More...
__api void *	iio_channel_get_data (const struct iio_channel *chn)
	Retrieve a previously associated pointer of an iio_channel structure. More...

Detailed Description

Function Documentation

iio_channel_attr_get_filename()

__api __pure const char* iio_channel_attr_get_filename	(	const struct iio_channel *	chn,
		const char *	attr
	)

Retrieve the filename of an attribute.

Parameters

chn	A pointer to an iio_channel structure
attr	a NULL-terminated string corresponding to the name of the attribute

Returns

On success, a pointer to a static NULL-terminated string

If the attribute name is unknown, NULL is returned

iio_channel_attr_read()

__api ssize_t iio_channel_attr_read	(	const struct iio_channel *	chn,
		const char *	attr,
		char *	dst,
		size_t	len
	)

Read the content of the given channel-specific attribute.

Parameters

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
dst	A pointer to the memory area where the NULL-terminated string corresponding to the value read will be stored
len	The available length of the memory area, in bytes

Returns

On success, the number of bytes written to the buffer

On error, a negative errno code is returned

NOTE:By passing NULL as the "attr" argument to iio_channel_attr_read, it is now possible to read all of the attributes of a channel.

The buffer is filled with one block of data per attribute of the channel, by the order they appear in the iio_channel structure.

The first four bytes of one block correspond to a 32-bit signed value in network order. If negative, it corresponds to the errno code that were returned when reading the attribute; if positive, it corresponds to the length of the data read. In that case, the rest of the block contains the data.

iio_channel_attr_read_all()

__api int iio_channel_attr_read_all	(	struct iio_channel *	chn,
		int(*)(struct iio_channel *chn, const char *attr, const char *val, size_t len, void *d)	cb,
		void *	data
	)

Read the content of all channel-specific attributes.

Parameters

chn	A pointer to an iio_channel structure
cb	A pointer to a callback function
data	A pointer that will be passed to the callback function

Returns

On success, 0 is returned

On error, a negative errno code is returned

NOTE: This function is especially useful when used with the network backend, as all the channel-specific attributes are read in one single command.

iio_channel_attr_read_bool()

__api int iio_channel_attr_read_bool	(	const struct iio_channel *	chn,
		const char *	attr,
		bool *	val
	)

Read the content of the given channel-specific attribute.

Parameters

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
val	A pointer to a bool variable where the value should be stored

Returns

On success, 0 is returned

On error, a negative errno code is returned

iio_channel_attr_read_double()

__api int iio_channel_attr_read_double	(	const struct iio_channel *	chn,
		const char *	attr,
		double *	val
	)

Read the content of the given channel-specific attribute.

Parameters

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
val	A pointer to a double variable where the value should be stored

Returns

On success, 0 is returned

On error, a negative errno code is returned

iio_channel_attr_read_longlong()

__api int iio_channel_attr_read_longlong	(	const struct iio_channel *	chn,
		const char *	attr,
		long long *	val
	)

Read the content of the given channel-specific attribute.

Parameters

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
val	A pointer to a long long variable where the value should be stored

Returns

On success, 0 is returned

On error, a negative errno code is returned

iio_channel_attr_write()

__api ssize_t iio_channel_attr_write	(	const struct iio_channel *	chn,
		const char *	attr,
		const char *	src
	)

Set the value of the given channel-specific attribute.

Parameters

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
src	A NULL-terminated string to set the attribute to

Returns

On success, the number of bytes written

On error, a negative errno code is returned

NOTE:By passing NULL as the "attr" argument to iio_channel_attr_write, it is now possible to write all of the attributes of a channel.

The buffer must contain one block of data per attribute of the channel, by the order they appear in the iio_channel structure.

The first four bytes of one block correspond to a 32-bit signed value in network order. If negative, the attribute is not written; if positive, it corresponds to the length of the data to write. In that case, the rest of the block must contain the data.

iio_channel_attr_write_all()

__api int iio_channel_attr_write_all	(	struct iio_channel *	chn,
		ssize_t(*)(struct iio_channel *chn, const char *attr, void *buf, size_t len, void *d)	cb,
		void *	data
	)

Set the values of all channel-specific attributes.

Parameters

chn	A pointer to an iio_channel structure
cb	A pointer to a callback function
data	A pointer that will be passed to the callback function

Returns

On success, 0 is returned

On error, a negative errno code is returned

NOTE: This function is especially useful when used with the network backend, as all the channel-specific attributes are written in one single command.

iio_channel_attr_write_bool()

__api int iio_channel_attr_write_bool	(	const struct iio_channel *	chn,
		const char *	attr,
		bool	val
	)

Set the value of the given channel-specific attribute.

Parameters

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
val	A bool value to set the attribute to

Returns

On success, 0 is returned

On error, a negative errno code is returned

iio_channel_attr_write_double()

__api int iio_channel_attr_write_double	(	const struct iio_channel *	chn,
		const char *	attr,
		double	val
	)

Set the value of the given channel-specific attribute.

Parameters

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
val	A double value to set the attribute to

Returns

On success, 0 is returned

On error, a negative errno code is returned

iio_channel_attr_write_longlong()

__api int iio_channel_attr_write_longlong	(	const struct iio_channel *	chn,
		const char *	attr,
		long long	val
	)

Set the value of the given channel-specific attribute.

Parameters

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
val	A long long value to set the attribute to

Returns

On success, 0 is returned

On error, a negative errno code is returned

iio_channel_attr_write_raw()

__api ssize_t iio_channel_attr_write_raw	(	const struct iio_channel *	chn,
		const char *	attr,
		const void *	src,
		size_t	len
	)

Set the value of the given channel-specific attribute.

Parameters

chn	A pointer to an iio_channel structure
attr	A NULL-terminated string corresponding to the name of the attribute
src	A pointer to the data to be written
len	The number of bytes that should be written

Returns

On success, the number of bytes written

On error, a negative errno code is returned

iio_channel_disable()

__api void iio_channel_disable

(

struct iio_channel *

chn

)

Disable the given channel.

Parameters

chn	A pointer to an iio_channel structure

iio_channel_enable()

__api void iio_channel_enable

(

struct iio_channel *

chn

)

Enable the given channel.

Parameters

chn	A pointer to an iio_channel structure

NOTE:Before creating an iio_buffer structure with iio_device_create_buffer, it is required to enable at least one channel of the device to read from.

iio_channel_find_attr()

__api __pure const char* iio_channel_find_attr	(	const struct iio_channel *	chn,
		const char *	name
	)

Try to find a channel-specific attribute by its name.

Parameters

chn	A pointer to an iio_channel structure
name	A NULL-terminated string corresponding to the name of the attribute

Returns

On success, a pointer to a static NULL-terminated string

If the name does not correspond to any known attribute of the given channel, NULL is returned

NOTE: This function is useful to detect the presence of an attribute. It can also be used to retrieve the name of an attribute as a pointer to a static string from a dynamically allocated string.

iio_channel_get_attr()

__api __pure const char* iio_channel_get_attr	(	const struct iio_channel *	chn,
		unsigned int	index
	)

Get the channel-specific attribute present at the given index.

Parameters

chn	A pointer to an iio_channel structure
index	The index corresponding to the attribute

Returns

On success, a pointer to a static NULL-terminated string

If the index is invalid, NULL is returned

iio_channel_get_attrs_count()

__api __pure unsigned int iio_channel_get_attrs_count

(

const struct iio_channel *

chn

)

Enumerate the channel-specific attributes of the given channel.

Parameters

chn	A pointer to an iio_channel structure

Returns

The number of channel-specific attributes found

iio_channel_get_data()

__api void* iio_channel_get_data

(

const struct iio_channel *

chn

)

Retrieve a previously associated pointer of an iio_channel structure.

Parameters

chn	A pointer to an iio_channel structure

Returns

The pointer previously associated if present, or NULL

iio_channel_get_device()

__api __pure const struct iio_device* iio_channel_get_device

(

const struct iio_channel *

chn

)

Retrieve a pointer to the iio_device structure.

Parameters

chn	A pointer to an iio_channel structure

Returns

A pointer to an iio_device structure

iio_channel_get_id()

__api __pure const char* iio_channel_get_id

(

const struct iio_channel *

chn

)

Retrieve the channel ID (e.g. voltage0)

Parameters

chn	A pointer to an iio_channel structure

Returns

A pointer to a static NULL-terminated string

iio_channel_get_name()

__api __pure const char* iio_channel_get_name

(

const struct iio_channel *

chn

)

Retrieve the channel name (e.g. vccint)

Parameters

chn	A pointer to an iio_channel structure

Returns

A pointer to a static NULL-terminated string

NOTE: if the channel has no name, NULL is returned.

iio_channel_is_enabled()

__api bool iio_channel_is_enabled

(

const struct iio_channel *

chn

)

Returns True if the channel is enabled.

Parameters

chn	A pointer to an iio_channel structure

Returns

True if the channel is enabled, False otherwise

iio_channel_is_output()

__api __pure bool iio_channel_is_output

(

const struct iio_channel *

chn

)

Return True if the given channel is an output channel.

Parameters

chn	A pointer to an iio_channel structure

Returns

True if the channel is an output channel, False otherwise

iio_channel_is_scan_element()

__api __pure bool iio_channel_is_scan_element

(

const struct iio_channel *

chn

)

Return True if the given channel is a scan element.

Parameters

chn	A pointer to an iio_channel structure

Returns

True if the channel is a scan element, False otherwise

NOTE: a channel that is a scan element is a channel that can generate samples (for an input channel) or receive samples (for an output channel) after being enabled.

iio_channel_read()

__api size_t iio_channel_read	(	const struct iio_channel *	chn,
		struct iio_buffer *	buffer,
		void *	dst,
		size_t	len
	)

Demultiplex and convert the samples of a given channel

Parameters

chn	A pointer to an iio_channel structure
buffer	A pointer to an iio_buffer structure
dst	A pointer to the memory area where the converted data will be stored
len	The available length of the memory area, in bytes

Returns

The size of the converted data, in bytes

iio_channel_read_raw()

__api size_t iio_channel_read_raw	(	const struct iio_channel *	chn,
		struct iio_buffer *	buffer,
		void *	dst,
		size_t	len
	)

Demultiplex the samples of a given channel

Parameters

chn	A pointer to an iio_channel structure
buffer	A pointer to an iio_buffer structure
dst	A pointer to the memory area where the demultiplexed data will be stored
len	The available length of the memory area, in bytes

Returns

The size of the demultiplexed data, in bytes

iio_channel_set_data()

__api void iio_channel_set_data	(	struct iio_channel *	chn,
		void *	data
	)

Associate a pointer to an iio_channel structure.

Parameters

chn	A pointer to an iio_channel structure
data	The pointer to be associated

iio_channel_write()

__api size_t iio_channel_write	(	const struct iio_channel *	chn,
		struct iio_buffer *	buffer,
		const void *	src,
		size_t	len
	)

Convert and multiplex the samples of a given channel

Parameters

chn	A pointer to an iio_channel structure
buffer	A pointer to an iio_buffer structure
src	A pointer to the memory area where the sequential data will be read from
len	The length of the memory area, in bytes

Returns

The number of bytes actually converted and multiplexed

iio_channel_write_raw()

__api size_t iio_channel_write_raw	(	const struct iio_channel *	chn,
		struct iio_buffer *	buffer,
		const void *	src,
		size_t	len
	)

Multiplex the samples of a given channel

Parameters

chn	A pointer to an iio_channel structure
buffer	A pointer to an iio_buffer structure
src	A pointer to the memory area where the sequential data will be read from
len	The length of the memory area, in bytes

Returns

The number of bytes actually multiplexed