NAME

gpio_open, gpio_close — library to handle GPIO pins

LIBRARY

General-Purpose Input Output (GPIO) library (libgpio, -lgpio)

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 <rpaulo@FreeBSD.org>.