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Ubuntu系统下操作GPIO

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最近有项目需要用到RK3568的GPIO进行功能开发，找到关于GPIO操作例程，特此记录一下，例程是基于英伟达开发板的，简单修改一下就可以应用到RK3568,中间可能需要修改设备树，这里略过设备树修改，以后会再专门讲解
首先使用shell命令测试一下

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echo 192 > /sys/class/gpio/export
#导出编号为192的gpio
#如果这个gpio导出成功，会多出一个文件夹/sys/class/gpio/gpio192/
echo 192 > /sys/class/gpio/unexport
#取消导出

echo out > /sys/class/gpio/gpio192/direction
#设置为输出
echo 1 > /sys/class/gpio/gpio192/value
#输出高

echo in > /sys/class/gpio/gpio192/direction
#设置为输入
cat /sys/class/gpio/gpio192/value
#读取输入值

#也可以直接向value中写入high或low，gpio被设置成输出，并输出对应电平
echo high > /sys/class/gpio/gpio192/value
#设置为输出，并输出高电平

#上述命令都会需要root权限

每个芯片都有自己的gpio编号计算公式，需要先将引脚编号转换成数字编号再进行操作

例如瑞芯微RK3399的gpio编号计算方式：

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GPIOn_Kx
编号 = n*32 + (K-A)*8 + x

GPIO1_B3 = 1*32 + (B-A)*8 + 3 = 43

.h文件

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/*
    NVIDIA Jetson Xavier NX 控制GPIO
    在linux系统中以文件io的方式控制GPIO示例，开发板为NVIDIA Jetson Xavier NX，其它公司的开发板也可使用。
    此代码功能：GPIO-09接入蜂鸣器，高电平开启，低电平关闭。
*/
 
#ifndef NVIDIAGPIO_H
#define NVIDIAGPIO_H
 
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <unistd.h>
#include <fcntl.h>
#include <iostream>
 
using namespace std;
 
#define ON "1"              //开启
#define OFF "0"             //关闭
#define BUZZER "436"        //控制蜂鸣器引脚
#define DIRECTION_OUT "out"     //方向为输出
#define DIRECTION_IN "in"     //方向为输出
 
class NvidiaGpio
{
public:
    NvidiaGpio();
    ~NvidiaGpio();
 
    int openGpio(const char *port); //导入GPIO
    int closeGpio(const char *port); //导出GPIO
 
    int setGpioDirection(const char *port, const char *direction); //设置GPIO输入/输出模式
 
    int writeGpioValue(const char *port, const char *value); //设置GPIO值
    int readGpioValue(const char *port); //读取GPIO值
};
 
#endif // NVIDIAGPIO_H

.cpp文件

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#include "nvidiagpio.h"
 
NvidiaGpio::NvidiaGpio()
{
 
}
 
NvidiaGpio::~NvidiaGpio()
{
 
}
 
int NvidiaGpio::openGpio(const char *port)
{
    int fd = -1;
    const char *path = "/sys/class/gpio/export";
 
    if((fd = open(path, O_WRONLY)) == -1) {
        perror("Failed to open gpio! ");
        return -1;
    }
 
    write(fd, port, sizeof(port));
    close(fd);
 
    return 0;
}
 
int NvidiaGpio::closeGpio(const char *port)
{
    int fd = -1;
    const char *path = "/sys/class/gpio/unexport";
 
    if((fd = open(path, O_WRONLY)) == -1) {
        perror("Failed to close gpio! ");
        return -1;
    }
 
    write(fd, port, sizeof(port));
    close(fd);
 
    return 0;
}
 
int NvidiaGpio::setGpioDirection(const char *port, const char *direction)
{
    int fd = -1;
    char path[40] = {0};
    sprintf(path, "/sys/class/gpio/gpio%s/direction", port);
 
    if((fd = open(path, O_WRONLY)) == -1) {
        perror("Failed to set GPIO dirention! ");
        return -1;
    }
 
    write(fd, direction, sizeof(direction));
    close(fd);
 
    return 0;
}
 
int NvidiaGpio::writeGpioValue(const char *port, const char *value)
{
    int fd = -1;
    char path[40] = {0};
    sprintf(path, "/sys/class/gpio/gpio%s/value", port);
 
    if((fd = open(path, O_WRONLY)) == -1) {
        perror("Failed to set GPIO value! ");
        return -1;
    }
 
    write(fd, value, sizeof(value));
    close(fd);
 
    return 0;
}
 
int NvidiaGpio::readGpioValue(const char *port)
{
    int fd = -1;
    int value = 0;
    char path[40] = {0};
    sprintf(path, "/sys/class/gpio/gpio%s/value", port);
 
    if((fd = open(path, O_RDONLY)) == -1) {
        perror("Failed to set GPIO value! ");
        return -1;
    }
 
    char tmp[2] = {0};
    read(fd, tmp, 1);
    close(fd);
 
    value = atoi(tmp);
 
    return value;
}

main.cpp文件

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#include <iostream>
#include "nvidiagpio.h"
 
using namespace std;
 
int main()
{
    cout << "Hello World!" << endl;
 
    NvidiaGpio *gpio = new NvidiaGpio();
 
    if(gpio->openGpio(BUZZER) != 0) { //打开gpio
        exit(1);
    }
 
    usleep(10*1000);
 
    if(gpio->setGpioDirection(BUZZER, DIRECTION_OUT) != 0) { // 设置GPIO方向
        gpio->closeGpio(BUZZER);
        exit(1);
    }
 
    usleep(10*1000);
 
    if(gpio->writeGpioValue(BUZZER, ON) != 0) { //设置高电平为输出，开启蜂鸣器
        gpio->closeGpio(BUZZER);
        exit(1);
    }
 
    int ret = 0;
    ret = gpio->readGpioValue(BUZZER);
    cout<<"get gpio value: "<<ret<<endl;
 
    sleep(1);
 
    if(gpio->writeGpioValue(BUZZER, OFF) != 0) { //设置低电平为输出，关闭蜂鸣器
        gpio->closeGpio(BUZZER);
        exit(1);
    }
 
    ret = gpio->readGpioValue(BUZZER);
    cout<<"get gpio value: "<<ret<<endl;
 
    gpio->closeGpio(BUZZER);
 
    return 0;
}
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