API Description

Gpio is the General Purpose IO interface to libmraa. Its features depend on the board type used, it can use gpiolibs (exported via a kernel module through sysfs), or memory mapped IO via a /dev/uio device or /dev/mem depending again on the board configuration.

    /* initialize GPIO pin */
    gpio_1 = mraa_gpio_init(GPIO_PIN_1);
    if (gpio_1 == NULL) {
        fprintf(stderr, "Failed to initialize GPIO %d\n", GPIO_PIN_1);
        mraa_deinit();
        return EXIT_FAILURE;
    }
    /* initialize GPIO pin */
    gpio_2 = mraa_gpio_init(GPIO_PIN_2);
    if (gpio_2 == NULL) {
        fprintf(stderr, "Failed to initialize GPIO %d\n", GPIO_PIN_2);
        mraa_deinit();
        return EXIT_FAILURE;
    }
    /* set GPIO to output */
    status = mraa_gpio_dir(gpio_1, MRAA_GPIO_OUT);
    if (status != MRAA_SUCCESS) {
        goto err_exit;
    }
    /* set GPIO to output */
    status = mraa_gpio_dir(gpio_2, MRAA_GPIO_OUT);
    if (status != MRAA_SUCCESS) {
        goto err_exit;
    }
    /* toggle both GPIO's */
    while (flag) {
        status = mraa_gpio_write(gpio_1, 1);
        if (status != MRAA_SUCCESS) {
            goto err_exit;
        }
        status = mraa_gpio_write(gpio_2, 0);
        if (status != MRAA_SUCCESS) {
            goto err_exit;
        }
        sleep(1);
        status = mraa_gpio_write(gpio_1, 0);
        if (status != MRAA_SUCCESS) {
            goto err_exit;
        }
        status = mraa_gpio_write(gpio_2, 1);
        if (status != MRAA_SUCCESS) {
            goto err_exit;
        }
        sleep(1);
    }
    /* release gpio's */
    status = mraa_gpio_close(gpio_1);
    if (status != MRAA_SUCCESS) {
        goto err_exit;
    }
    /* close GPIO */
    status = mraa_gpio_close(gpio_2);
    if (status != MRAA_SUCCESS) {
        goto err_exit;
    }

Go to the source code of this file.

Data Structures
struct	mraa_gpio_event

Functions
mraa_gpio_context	mraa_gpio_init (int pin)

mraa_gpio_context	mraa_gpio_init_multi (int pins[], int num_pins)

mraa_gpio_context	mraa_gpio_init_raw (int gpiopin)

mraa_result_t	mraa_gpio_edge_mode (mraa_gpio_context dev, mraa_gpio_edge_t mode)

mraa_result_t	mraa_gpio_isr (mraa_gpio_context dev, mraa_gpio_edge_t edge, void(fptr)(void ), void *args)

mraa_gpio_events_t	mraa_gpio_get_events (mraa_gpio_context dev)

mraa_result_t	mraa_gpio_isr_exit (mraa_gpio_context dev)

mraa_result_t	mraa_gpio_mode (mraa_gpio_context dev, mraa_gpio_mode_t mode)

mraa_result_t	mraa_gpio_dir (mraa_gpio_context dev, mraa_gpio_dir_t dir)

mraa_result_t	mraa_gpio_read_dir (mraa_gpio_context dev, mraa_gpio_dir_t *dir)

mraa_result_t	mraa_gpio_close (mraa_gpio_context dev)

int	mraa_gpio_read (mraa_gpio_context dev)

mraa_result_t	mraa_gpio_read_multi (mraa_gpio_context dev, int output_values[])

mraa_result_t	mraa_gpio_write (mraa_gpio_context dev, int value)

mraa_result_t	mraa_gpio_write_multi (mraa_gpio_context dev, int input_values[])

mraa_result_t	mraa_gpio_owner (mraa_gpio_context dev, mraa_boolean_t owner)

DEPRECATED mraa_result_t	mraa_gpio_use_mmaped (mraa_gpio_context dev, mraa_boolean_t mmap)

int	mraa_gpio_get_pin (mraa_gpio_context dev)

int	mraa_gpio_get_pin_raw (mraa_gpio_context dev)

mraa_result_t	mraa_gpio_input_mode (mraa_gpio_context dev, mraa_gpio_input_mode_t mode)

mraa_result_t	mraa_gpio_out_driver_mode (mraa_gpio_context dev, mraa_gpio_out_driver_mode_t mode)

Typedefs
typedef struct _gpio *	mraa_gpio_context

typedef long long unsigned int	mraa_timestamp_t

typedef mraa_gpio_event *	mraa_gpio_events_t

Enumerations
enum	mraa_gpio_mode_t { MRAA_GPIO_STRONG = 0, MRAA_GPIO_PULLUP = 1, MRAA_GPIO_PULLDOWN = 2, MRAA_GPIO_HIZ = 3, MRAA_GPIOD_ACTIVE_LOW = 4, MRAA_GPIOD_OPEN_DRAIN = 5, MRAA_GPIOD_OPEN_SOURCE = 6 }

enum	mraa_gpio_dir_t { MRAA_GPIO_OUT = 0, MRAA_GPIO_IN = 1, MRAA_GPIO_OUT_HIGH = 2, MRAA_GPIO_OUT_LOW = 3 }

enum	mraa_gpio_edge_t { MRAA_GPIO_EDGE_NONE = 0, MRAA_GPIO_EDGE_BOTH = 1, MRAA_GPIO_EDGE_RISING = 2, MRAA_GPIO_EDGE_FALLING = 3 }

enum	mraa_gpio_input_mode_t { MRAA_GPIO_ACTIVE_HIGH = 0, MRAA_GPIO_ACTIVE_LOW = 1 }

enum	mraa_gpio_out_driver_mode_t { MRAA_GPIO_OPEN_DRAIN = 0, MRAA_GPIO_PUSH_PULL = 1 }

Function Documentation

mraa_gpio_context mraa_gpio_init ( int pin )

Initialise gpio_context, based on board number

Parameters

pin	Pin number read from the board, i.e IO3 is 3

Returns: gpio context or NULL

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mraa_gpio_context mraa_gpio_init_multi	(	int	pins[],
		int	num_pins
	)

Initialise gpio_context, based on board number, for multiple pins (can be one).

Parameters

pins	Pin array read from the board
num_pins	Number of pins - must be the same as the pins array length provided as the first argument.

Returns: gpio context or NULL

mraa_gpio_context mraa_gpio_init_raw ( int gpiopin )

Initialise gpio context without any mapping to a pin

Parameters

gpiopin gpio pin as listed in SYSFS

Returns: gpio context or NULL

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mraa_result_t mraa_gpio_edge_mode	(	mraa_gpio_context	dev,
		mraa_gpio_edge_t	mode
	)

Set the edge mode on the gpio

Parameters

dev	The Gpio context
mode	The edge mode to set the gpio into

Returns: Result of operation

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mraa_result_t mraa_gpio_isr	(	mraa_gpio_context	dev,
		mraa_gpio_edge_t	edge,
		void()(void )	fptr,
		void *	args
	)

Set an interrupt on pin(s).

Parameters

dev	The Gpio context
edge	The edge mode to set the gpio(s) into
fptr	Function pointer to function to be called when interrupt is triggered
args	Arguments passed to the interrupt handler (fptr)

Returns: Result of operation

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mraa_gpio_events_t mraa_gpio_get_events ( mraa_gpio_context dev )

Get an array of structures describing triggered events.

Parameters

dev	The Gpio context

Returns: Array of structures containing pairs of pin id's and the associated timestamp. An event with negative id value indicates that no event was triggered for the respective pin. The array length is that of the number of pins provided in mraa_gpio_init_multi().

mraa_result_t mraa_gpio_isr_exit ( mraa_gpio_context dev )

Stop the current interrupt watcher on this Gpio, and set the Gpio edge mode to MRAA_GPIO_EDGE_NONE(only for sysfs interface).

Parameters

dev	The Gpio context

Returns: Result of operation

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mraa_result_t mraa_gpio_mode	(	mraa_gpio_context	dev,
		mraa_gpio_mode_t	mode
	)

Set Gpio(s) Output Mode,

Parameters

dev	The Gpio context
mode	The Gpio(s) Output Mode

Returns: Result of operation

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mraa_result_t mraa_gpio_dir	(	mraa_gpio_context	dev,
		mraa_gpio_dir_t	dir
	)

Set Gpio(s) direction

Parameters

dev	The Gpio context
dir	The direction of the Gpio(s)

Returns: Result of operation

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mraa_result_t mraa_gpio_read_dir	(	mraa_gpio_context	dev,
		mraa_gpio_dir_t *	dir
	)

Read Gpio(s) direction

Parameters

dev	The Gpio context
dir	The address where to store the Gpio(s) direction

Returns: Result of operation

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mraa_result_t mraa_gpio_close ( mraa_gpio_context dev )

Close the Gpio context

Will free the memory for the context and unexport the Gpio - sysfs interface.
Will free up the memory used by context and close related file descriptors - chardev interface.

Parameters

dev	The Gpio context

Returns: Result of operation

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int mraa_gpio_read ( mraa_gpio_context dev )

Read the Gpio value. This can be 0 or 1. A resonse of -1 means that there was a fatal error.

Parameters

dev	The Gpio context

Returns: Result of operation

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mraa_result_t mraa_gpio_read_multi	(	mraa_gpio_context	dev,
		int	output_values[]
	)

Read the Gpio(s) value. The user must provide an integer array with a length equal to the number of pins provided to mraa_gpio_init_multi() function.

Parameters

dev	The Gpio context
output_values	The array provided by the user. Existing values will be overwritten with the newly read ones.

Returns: Result of operation

mraa_result_t mraa_gpio_write	(	mraa_gpio_context	dev,
		int	value
	)

Write to the Gpio Value.

Parameters

dev	The Gpio context
value	Integer value to write

Returns: Result of operation

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mraa_result_t mraa_gpio_write_multi	(	mraa_gpio_context	dev,
		int	input_values[]
	)

Write to the Gpio(s) Value. The user must provide an integer array with a length equal to the number of pins provided to mraa_gpio_init_multi() function.

Parameters

dev	The Gpio context
output_values	The array provided by the user. It must contain the values intended to be written to the gpio pins, in the same order as the init function.

Returns: Result of operation

mraa_result_t mraa_gpio_owner	(	mraa_gpio_context	dev,
		mraa_boolean_t	owner
	)

Change ownership of the context.

Parameters

dev	The Gpio context
owner	Does this context own the pin

Returns: Result of operation

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DEPRECATED mraa_result_t mraa_gpio_use_mmaped	(	mraa_gpio_context	dev,
		mraa_boolean_t	mmap
	)

Enable using memory mapped io instead of sysfs, chardev based I/O can be considered memorymapped

Deprecated:

Parameters

dev	The Gpio context
mmap	Use mmap instead of sysfs

Returns: Result of operation

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int mraa_gpio_get_pin ( mraa_gpio_context dev )

Get a pin number of the gpio, invalid will return -1

Parameters

dev	The Gpio context

Returns: Pin number

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int mraa_gpio_get_pin_raw ( mraa_gpio_context dev )

Get a gpio number as used within sysfs, invalid will return -1

Parameters

dev	The Gpio context

Returns: gpio number

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mraa_result_t mraa_gpio_input_mode	(	mraa_gpio_context	dev,
		mraa_gpio_input_mode_t	mode
	)

Set Gpio input mode

Parameters

dev	The Gpio context
mode	Mode to set input pin state

Returns: Result of operation

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mraa_result_t mraa_gpio_out_driver_mode	(	mraa_gpio_context	dev,
		mraa_gpio_out_driver_mode_t	mode
	)

Set Gpio output driver mode. This is not a standard feature, it needs custom implementation for each board

Parameters

dev	The Gpio context
mode	Set output driver mode

Returns: Result of operation

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Typedef Documentation

typedef struct _gpio* mraa_gpio_context

Opaque pointer definition to the internal struct _gpio

Enumeration Type Documentation

enum mraa_gpio_mode_t

Gpio Output modes

Enumerator
MRAA_GPIO_STRONG	Default. Strong high and low
MRAA_GPIO_PULLUP	Resistive High
MRAA_GPIO_PULLDOWN	Resistive Low
MRAA_GPIO_HIZ	High Z State

enum mraa_gpio_dir_t

Gpio Direction options

Enumerator
MRAA_GPIO_OUT	Output. A Mode can also be set
MRAA_GPIO_IN	Input
MRAA_GPIO_OUT_HIGH	Output. Init High
MRAA_GPIO_OUT_LOW	Output. Init Low

enum mraa_gpio_edge_t

Gpio Edge types for interrupts

Enumerator
MRAA_GPIO_EDGE_NONE	No interrupt on Gpio
MRAA_GPIO_EDGE_BOTH	Interrupt on rising & falling
MRAA_GPIO_EDGE_RISING	Interrupt on rising only
MRAA_GPIO_EDGE_FALLING	Interrupt on falling only

enum mraa_gpio_input_mode_t

Gpio input modes

Enumerator
MRAA_GPIO_ACTIVE_HIGH	Resistive High
MRAA_GPIO_ACTIVE_LOW	Resistive Low

enum mraa_gpio_out_driver_mode_t

Gpio output driver modes

Enumerator
MRAA_GPIO_OPEN_DRAIN	Open Drain Configuration
MRAA_GPIO_PUSH_PULL	Push Pull Configuration

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API Description

Data Structures

Functions

Typedefs

Enumerations

Function Documentation

Typedef Documentation

Enumeration Type Documentation