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Linux操作GPIO（文件IO方式）_Leon-CSDN博客

在Linux 中的应用层操作gpio的方法_仗劍走天涯-CSDN博客

位置

控制GPIO的目录位于/sys/class/gpio

例子

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1. 导出
/sys/class/gpio# echo 44 > export
2. 设置方向
/sys/class/gpio/gpio44# echo out > direction
3. 查看方向
/sys/class/gpio/gpio44# cat direction
4. 设置输出
/sys/class/gpio/gpio44# echo 1 > value
5. 查看输出值
/sys/class/gpio/gpio44# cat value
6. 取消导出
/sys/class/gpio# echo 44 > unexport

以echo的形式调用system函数进行操作，这种形式编程比较简单，结构比较清晰，如下

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void set_gpio64_low(void)  
{     
    system("echo 64 > /sys/class/gpio/export");  
    system("echo out > /sys/class/gpio/gpio64/direction");  
    system("echo 0 > /sys/class/gpio/gpio64/value");  
}

通过文件的形式来调用

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#include <stdio.h>
 
#include <stdlib.h>
 
#include <string.h>
#include <unistd.h>
#include <fcntl.h>   //define O_WRONLY and O_RDONLY
 
void initGpio(int n)
{
    FILE * fp =fopen("/sys/class/gpio/export","w");
    if (fp == NULL)
        perror("export open filed");
    else
        fprintf(fp,"%d",n);
    fclose(fp);
}   //create gpio file
 
void setGpioDirection(int n,char *direction)
{
    char path[100] = {0};
    sprintf(path,"/sys/class/gpio/gpio%d/direction",n);
    FILE * fp =fopen(path,"w");
    if (fp == NULL)
        perror("direction open filed");
    else
        fprintf(fp,"%s",direction);
    fclose(fp);
}   //set gpio "in" or "out"
 
int getGpioValue(int n)
{
    char path[64];
    char value_str[3];
    int fd;
 
    snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/value", n);
    fd = open(path, O_RDONLY);
    if (fd < 0) {
        perror("Failed to open gpio value for reading!");
        return -1;
    }
 
    if (read(fd, value_str, 3) < 0) {
        perror("Failed to read value!");
        return -1;
    }
 
    close(fd);
    return (atoi(value_str));
}   //get gpio(n)'s value

void setGpioValue(int n,int value)
{
    char path[64];
    char value_str[3];
    int fd;
 
    snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/value", n);
    fd = open(path, O_WRONLY);
    if (fd < 0) {
        perror("Failed to open gpio value for writing!");
        return;
    }
 
    if (value)
        strcpy(value_str,"1");
    else
        strcpy(value_str,"0");
 
    if (write(fd, value_str, 1) != 1) {
        perror("Failed to write value!");
        return;
    }
 
    close(fd);
}   //set gpio(n)'s value
 
int main()
 
{
    initGpio(18);
    setGpioDirection(18,(char*)"out");
    while(1)
    {
        setGpioValue(18,0);
        printf("%d\n",getGpioValue(18));//每隔1s输出一次gpio18的值
        sleep(1);
        setGpioValue(18,1);
        printf("%d\n",getGpioValue(18));//每隔1s输出一次gpio18的值
        sleep(1);
    }
 
    return 0;
 
}