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GPIO(3) Library Functions Manual GPIO(3)

gpio_open, gpio_close — library to handle GPIO pins

library “libgpio”

#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);

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 () or (). When no more GPIO operations are needed, this handle can be destroyed with ().

To get a list of all available pins, one can call (). 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 () 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 () sets the name used to describe a pin.

The function () 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 () and () are available, respectively. To toggle the state, use ().

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

The functions (), (), (), (), (), (), (), (), () and () are wrappers around gpio_pin_set_flags().

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.

gpiobus(4), gpioctl(8)

The libgpio library first appeared in FreeBSD 11.0.

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

July 1, 2015 FreeBSD-13.0