GPIO_SYS

Gpio driver using sys file systeme.g.:

echo "4" > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio4/direction
echo "1"> /sys/class/gpio/gpio4/value
echo "4" > /sys/class/gpio/unexport

Installation

make install

Installs libgpio_sys.a and libgpio_sys.so in the directory $(PREFIX)/lib/. It also installs the include header file gpio.h in the directory $(PREFIX)/include/gpio_sys/. The default value for PREFIX is: PREFIX=usr. To use another location for installation changing the value of the PREFIX variable is needed. E.g.:

PREFIX=/usr/local/ make install

Uninstallation

make uninstall

Removes the files installed with the install make target.

NOTE: If PREFIX variable was changed during installation process the same value needs to be set for uninstallation. E.g.:

PREFIX=/usr/local/ make uninstall

Example

    #include <stdio.h>
    #include <stdlib.h>
    #include <unistd.h>
    #include <syslog.h>
    #include <stdbool.h>
    #include <gpio_sys/gpio.h>


    static const struct gpio_sys gpio_4 = {
        .pin = 4,
        .direction = 0, // out
    };

    int main(void)
    {
        int res, cnt;
        int value;

        openlog("gpio_sys", LOG_CONS | LOG_PID | LOG_NDELAY, LOG_LOCAL1);

        res = gpio_open(&gpio_4);
        if(res != EXIT_SUCCESS) {
            syslog(LOG_ERR, "Unable to open gpio %d\n", gpio_4.pin);
            return res;
        }

        gpio_write(&gpio_4, 1);
        for(cnt = 0; cnt < 10; cnt++) {
            if(cnt % 2) {
                gpio_write(&gpio_4, 1);
            } else {
                gpio_write(&gpio_4, 0);
            }
            value = gpio_read(&gpio_4);
            if(value < 0) {
                syslog(LOG_ERR, "Unable to read from gpio %d\n", gpio_4.pin);
                return EXIT_FAILURE;
            } else {
                printf("Gpio 4: %d\n", value);
            }
            sleep(1);
        }
        gpio_close(&gpio_4);

        return EXIT_SUCCESS;
    }

Additional make targets

Target	Meaning
all	Build the code, assemble the static and shared library.
install	Install the libraries and necessary include header files.
uninstall	Uninstall the libraries and necessary include header files.
clean	Clean up build artifacts.
distclean	Remove all directories created while any build step.
build_unit_test	Build the unit tests.
exec_unit_test	Execute the unit tests.
coverage	Determine code coverage of the unit tests.
check	Static code analysis (cppcheck).