gpio.h File Reference

API Description

Gpio is the General Purpose IO interface to libmraa. It's features depends 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 configuratio, or memory mapped IO via a /dev/uio device or /dev/mem depending again on the board configuration

    mraa_gpio_context gpio;

    gpio = mraa_gpio_init(6);

    mraa_gpio_dir(gpio, MRAA_GPIO_IN);

    for (;;) {
        fprintf(stdout, "Gpio is %d\n", mraa_gpio_read(gpio));
        sleep(1);
    }

    mraa_gpio_close(gpio);

Go to the source code of this file.

Functions
mraa_gpio_context	mraa_gpio_init (int pin)
mraa_gpio_context	mraa_gpio_init_raw (int gpiopin)
mraa_result_t	mraa_gpio_edge_mode (mraa_gpio_context dev, gpio_edge_t mode)
mraa_result_t	mraa_gpio_isr (mraa_gpio_context dev, gpio_edge_t edge, void(*fptr)(void *), void *args)
mraa_result_t	mraa_gpio_isr_exit (mraa_gpio_context dev)
mraa_result_t	mraa_gpio_mode (mraa_gpio_context dev, gpio_mode_t mode)
mraa_result_t	mraa_gpio_dir (mraa_gpio_context dev, 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_write (mraa_gpio_context dev, int value)
mraa_result_t	mraa_gpio_owner (mraa_gpio_context dev, mraa_boolean_t owner)
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)

Typedefs
typedef struct _gpio *	mraa_gpio_context

Enumerations
enum	gpio_mode_t { MRAA_GPIO_STRONG = 0, MRAA_GPIO_PULLUP = 1, MRAA_GPIO_PULLDOWN = 2, MRAA_GPIO_HIZ = 3 }
enum	gpio_dir_t { MRAA_GPIO_OUT = 0, MRAA_GPIO_IN = 1, MRAA_GPIO_OUT_HIGH = 2, MRAA_GPIO_OUT_LOW = 3 }
enum	gpio_edge_t { MRAA_GPIO_EDGE_NONE = 0, MRAA_GPIO_EDGE_BOTH = 1, MRAA_GPIO_EDGE_RISING = 2, MRAA_GPIO_EDGE_FALLING = 3 }

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_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,
		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,
		gpio_edge_t	edge,
		void(*)(void *)	fptr,
		void *	args
	)

Set an interupt on pin

Parameters

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

Returns

Result of operation

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mraa_result_t mraa_gpio_isr_exit

(

mraa_gpio_context

dev

)

Stop the current interupt watcher on this Gpio, and set the Gpio edge mode to MRAA_GPIO_EDGE_NONE

Parameters

dev	The Gpio context

Returns

Result of operation

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mraa_result_t mraa_gpio_mode	(	mraa_gpio_context	dev,
		gpio_mode_t	mode
	)

Set Gpio Output Mode,

Parameters

dev	The Gpio context
mode	The Gpio Output Mode

Returns

Result of operation

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mraa_result_t mraa_gpio_dir	(	mraa_gpio_context	dev,
		gpio_dir_t	dir
	)

Set Gpio direction

Parameters

dev	The Gpio context
dir	The direction of the Gpio

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

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_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_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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mraa_result_t mraa_gpio_use_mmaped	(	mraa_gpio_context	dev,
		mraa_boolean_t	mmap
	)

Enable using memory mapped io instead of sysfs

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

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

Parameters

dev	The Gpio context

Returns

gpio number

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Typedef Documentation

typedef struct _gpio* mraa_gpio_context

Opaque pointer definition to the internal struct _gpio

Enumeration Type Documentation

enum 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 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 gpio_edge_t

Gpio Edge types for interupts

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

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