GPIO控制输出高低电平

gpio.h

/*
 * GPIO user space helpers
 *
 * Copyright 2009 Analog Devices Inc.
 * Michael Hennerich ([email protected])
 *
 * Licensed under the GPL-2 or later
 */
 
#ifndef __GPIO_H_YP
#define __GPIO_H_YP



int gpio_export(unsigned gpio);
int gpio_unexport(unsigned gpio);
int gpio_dir_out(unsigned gpio);
int gpio_dir_in(unsigned gpio);
int gpio_set_value(unsigned gpio, unsigned value);
int gpio_get_value(unsigned gpio);




#endif

gpio.cpp

/*
 * GPIO user space helpers
 *
 * Copyright 2009 Analog Devices Inc.
 * Michael Hennerich ([email protected])
 *
 * Licensed under the GPL-2 or later
 */
 
#include 
#include 
#include 
#include 
#include 
#include 



#define GPIO_DIR_IN	    0
#define GPIO_DIR_OUT	1
 
int gpio_export(unsigned gpio)
{
	int fd, len;
	char buf[11];
 
	fd = open("/sys/class/gpio/export", O_WRONLY);
	if (fd < 0) {
		perror("gpio/export");
		return fd;
	}
 
	len = snprintf(buf, sizeof(buf), "%d", gpio);
	write(fd, buf, len);
	close(fd);
 
	return 0;
}
 
int gpio_unexport(unsigned gpio)
{
	int fd, len;
	char buf[11];
 
	fd = open("/sys/class/gpio/unexport", O_WRONLY);
	if (fd < 0) {
		perror("gpio/export");
		return fd;
	}
 
	len = snprintf(buf, sizeof(buf), "%d", gpio);
	write(fd, buf, len);
	close(fd);
	return 0;
}
 
int gpio_dir(unsigned gpio, unsigned dir)
{
	int fd, len;
	char buf[60];
 
	len = snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", gpio);
 
	fd = open(buf, O_WRONLY);
	if (fd < 0) {
		perror("gpio/direction");
		return fd;
	}
 
	if (dir == GPIO_DIR_OUT)
		write(fd, "out", 4);
	else
		write(fd, "in", 3);
 
	close(fd);
	return 0;
}
 
int gpio_dir_out(unsigned gpio)
{
	return gpio_dir(gpio, GPIO_DIR_OUT);
}
 
int gpio_dir_in(unsigned gpio)
{
	return gpio_dir(gpio, GPIO_DIR_IN);
}
 
int gpio_set_value(unsigned gpio, unsigned value)
{
	int fd, len;
	char buf[60];
 
	len = snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/value", gpio);
 
	fd = open(buf, O_WRONLY);
	if (fd < 0) {
		perror("gpio/value");
		return fd;
	}
 
	if (value)
		write(fd, "1", 2);
	else
		write(fd, "0", 2);
 
	close(fd);
	return 0;
}

int gpio_get_value(unsigned gpio)
{
	int fd, len, ret;
	char buf[60];
    
    ret = 0;
	len = snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/value", gpio);
 
	fd = open(buf, O_RDONLY);
	if (fd < 0) {
		perror("gpio/value");
		return fd;
	}
    
    char result[2]={0};

	if (read(fd, result, 2) < 0)
    {
       perror("read gpio/value err"); 
       ret = -1;
    }
    else
    {
        if (result[0] == '1')
        {
            ret  = 1;
        }
        else if (result[0] == '0')
        {
            ret = 0;
        }
        else
        {
            ret = -1;
        }
    }
	close(fd);
	return ret;
}

#if 0
int main(int argc, char *argv[])
{
	int i = 2;
 
	gpio_export(60);
	gpio_dir_out(60);
 
	while(i--) {
		gpio_set_value(60, i & 1);
		sleep(1);
	}
 
	gpio_unexport(60);
	
   
    i = 2;
    gpio_export(73);
	gpio_dir_out(73);
 
	while(i--) {
		gpio_set_value(73, i & 1);
		sleep(1);
	}
 
	gpio_unexport(73);
    
    gpio_export(42);
    gpio_dir_in(42);
    for (i = 0; i < 5; i++)
    {
        printf ("42 PB10 pin level:%d\n", gpio_get_value(42));
        sleep(1);
    }
    
    gpio_unexport(42);
}
#endif