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Manual Pages  — GPIO

NAME

gpio_open, gpio_close – library to handle GPIO pins

CONTENTS

LIBRARY

libgpio

SYNOPSIS

#include <sys/types.h>
#include <libgpio.h>

gpio_handle_t
gpio_open(unsigned int unit);

gpio_handle_t
gpio_open_device(const char *device);

void
gpio_close(gpio_handle_t handle);

int
gpio_pin_list(gpio_handle_t handle, gpio_config_t **pcfgs);

int
gpio_pin_config(gpio_handle_t handle, gpio_config_t *cfg);

int
gpio_pin_set_name(gpio_handle_t handle, gpio_pin_t pin, char *name);

int
gpio_pin_set_flags(gpio_handle_t handle, gpio_config_t *cfg);

gpio_value_t
gpio_pin_get(gpio_handle_t handle, gpio_pin_t pin);

int
gpio_pin_set(gpio_handle_t handle, gpio_pin_t pin, gpio_value_t value);

int
gpio_pin_toggle(gpio_handle_t handle, gpio_pin_t pin);

int
gpio_pin_low(gpio_handle_t handle, gpio_pin_t pin);

int
gpio_pin_high(gpio_handle_t handle, gpio_pin_t pin);

int
gpio_pin_input(gpio_handle_t handle, gpio_pin_t pin);

int
gpio_pin_output(gpio_handle_t handle, gpio_pin_t pin);

int
gpio_pin_opendrain(gpio_handle_t handle, gpio_pin_t pin);

int
gpio_pin_pushpull(gpio_handle_t handle, gpio_pin_t pin);

int
gpio_pin_tristate(gpio_handle_t handle, gpio_pin_t pin);

int
gpio_pin_pullup(gpio_handle_t handle, gpio_pin_t pin);

int
gpio_pin_pulldown(gpio_handle_t handle, gpio_pin_t pin);

int
gpio_pin_invin(gpio_handle_t handle, gpio_pin_t pin);

int
gpio_pin_invout(gpio_handle_t handle, gpio_pin_t pin);

int
gpio_pin_pulsate(gpio_handle_t handle, gpio_pin_t pin);

DESCRIPTION

The libgpio library provides an interface to configure GPIO pins. The library operates with a gpio_handle_t opaque type which can be created with gpio_open() or gpio_open_device(). When no more GPIO operations are needed, this handle can be destroyed with gpio_close().

To get a list of all available pins, one can call gpio_pin_list(). This function takes a pointer to a gpio_config_t which is dynamically allocated. This pointer should be freed with free(3) when it is no longer necessary.

The function gpio_pin_config() retrieves the current configuration of a pin. The pin number should be passed in via the g_pin variable which is part of the gpio_config_t structure.

The function gpio_pin_set_name() sets the name used to describe a pin.

The function gpio_pin_set_flags() configures a pin with the flags passed in by the gpio_config_t structure. The pin number should also be passed in through the g_pin variable. All other structure members will be ignored by this function. The list of flags can be found in /usr/include/sys/gpio.h.

The get or set the state of a GPIO pin, the functions gpio_pin_get() and gpio_pin_set() are available, respectively. To toggle the state, use gpio_pin_toggle().

The functions gpio_pin_low() and gpio_pin_high() are wrappers around gpio_pin_set().

The functions gpio_pin_input(), gpio_pin_output(), gpio_pin_opendrain(), gpio_pin_pushpull(), gpio_pin_tristate(), gpio_pin_pullup(), gpio_pin_pulldown(), gpio_pin_invin(), gpio_pin_invout() and gpio_pin_pulsate() are wrappers around gpio_pin_set_flags().

EXAMPLES

The following example shows how to configure pin 16 as output and then drive it high:
#include <sys/types.h>
#include <err.h>
#include <libgpio.h>

gpio_handle_t handle;

handle = gpio_open(0); if (handle == GPIO_INVALID_HANDLE)         err(1, "gpio_open failed"); gpio_pin_output(handle, 16); gpio_pin_high(handle, 16); gpio_close(handle);

The following example shows how to get a configuration of a pin:

gpio_config_t cfg;

cfg.g_pin = 32; gpio_pin_config(handle, &cfg);

The structure will contain the name of the pin and its flags.

SEE ALSO

gpiobus(4), gpioctl(8)

HISTORY

The libgpio library first appeared in FreeBSD 11.0 .

AUTHORS

The libgpio library was implemented by Rui Paulo <Mt rpaulo@FreeBSD.org>.

GPIO (3) July 1, 2015

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