Orange PI GPIO控制详细教程

一、sysfs方式

通过sysfs方式控制GPIO，先访问/sys/class/gpio目录，向export文件写入GPIO编号，使得该GPIO的操作接口从内核空间暴露到用户空间，GPIO的操作接口包括direction和value等，direction控制GPIO方向，而value可控制GPIO输出或获得GPIO输入。文件IO方式操作GPIO，使用到了4个函数open、close、read、write。

首先，看看系统中有没有”/sys/class/gpio”这个文件夹。如果没有请在编译内核的时候加入 Device Drivers-> GPIO Support ->/sys/class/gpio/… (sysfs interface)。

/sys/class/gpio 的使用说明：

gpio_operation 通过/sys/文件接口操作IO端口 GPIO到文件系统的映射

◇ 控制GPIO的目录位于/sys/class/gpio

◇ /sys/class/gpio/export文件用于通知系统需要导出控制的GPIO引脚编号

◇ /sys/class/gpio/unexport 用于通知系统取消导出

◇ /sys/class/gpio/gpiochipX目录保存系统中GPIO寄存器的信息，包括每个寄存器控制引脚的起始编号base，寄存器名称，引脚总数导出一个引脚的操作步骤

◇ 首先计算此引脚编号，引脚编号 = 控制引脚的寄存器基数 + 控制引脚寄存器位数

◇ 向/sys/class/gpio/export写入此编号，比如12号引脚，在shell中可以通过以下命令实现，命令成功后生成/sys/class/gpio/gpio12目录，如果没有出现相应的目录，说明此引脚不可导出

◇ direction文件，定义输入输入方向，可以通过下面命令定义为输出。direction接受的参数：in, out, high, low。high/low同时设置方向为输出，并将value设置为相应的1/0

◇ value文件是端口的数值，为1或0

几个例子：

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

二、文件读写例程

<span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#include<span style="color: black;"> stdlib.h
</span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#include<span style="color: black;"> stdio.h
</span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#include<span style="color: black;"> string.h
</span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#include<span style="color: black;"> unistd.h
</span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#include<span style="color: black;"> fcntl.h <span style="color: green;">/* define O_WRONLY and O_RDONLY */
</span></span></span><span style="color: green; font-size: 9pt;"><span style="font-family: Consolas; background-color: white;">/* </span><span style="font-family: 等线; background-color: white;">芯片复位引脚</span><span style="font-family: Consolas; background-color: white;">: P1_16 */
</span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#define<span style="color: black;"> SYSFS_GPIO_EXPORT    <span style="color: #a31515;">"/sys/class/gpio/export"
</span></span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#define<span style="color: black;"> SYSFS_GPIO_RST_PIN_VAL    <span style="color: #a31515;">"48"
</span></span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#define<span style="color: black;"> SYSFS_GPIO_RST_DIR    <span style="color: #a31515;">"/sys/class/gpio/gpio48/direction"
</span></span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#define<span style="color: black;"> SYSFS_GPIO_RST_DIR_VAL    <span style="color: #a31515;">"OUT"
</span></span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#define<span style="color: black;"> SYSFS_GPIO_RST_VAL    <span style="color: #a31515;">"/sys/class/gpio/gpio48/value"
</span></span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#define<span style="color: black;"> SYSFS_GPIO_RST_VAL_H    <span style="color: #a31515;">"1"
</span></span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#define<span style="color: black;"> SYSFS_GPIO_RST_VAL_L    <span style="color: #a31515;">"0"
</span></span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">int<span style="color: black;"> main()
</span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">{
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">int<span style="color: black;"> fd;
</span></span></span><span style="color: black; font-size: 9pt;"><span style="font-family: Consolas; background-color: white;">    <span style="color: green;">/* </span></span><span style="font-family: 等线; background-color: white;">打开端口</span><span style="color: green; font-family: Consolas; background-color: white;">/sys/class/gpio# echo 48 &gt; export */
</span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    fd = open( SYSFS_GPIO_EXPORT, O_WRONLY );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( fd == -1 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        printf( <span style="color: #a31515;">"ERR: Radio hard reset pin open error.\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(EXIT_FAILURE);
  </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">   }
 </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    write( fd, SYSFS_GPIO_RST_PIN_VAL, <span style="color: blue;">sizeof<span style="color: black;">(SYSFS_GPIO_RST_PIN_VAL) );
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    close( fd );
 </span><span style="color: black; font-size: 9pt;"><span style="font-family: Consolas; background-color: white;">    <span style="color: green;">/* </span></span><span style="font-family: 等线; background-color: white;">设置端口方向</span><span style="color: green; font-family: Consolas; background-color: white;">/sys/class/gpio/gpio48# echo out &gt; direction */
 </span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    fd = open( SYSFS_GPIO_RST_DIR, O_WRONLY );
 </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( fd == -1 )
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
 </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        printf( <span style="color: #a31515;">"ERR: Radio hard reset pin direction open error.\n"<span style="color: black;"> );
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(EXIT_FAILURE);
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
 </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    write( fd, SYSFS_GPIO_RST_DIR_VAL, <span style="color: blue;">sizeof<span style="color: black;">(SYSFS_GPIO_RST_DIR_VAL) );
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    close( fd );
 </span><span style="color: black; font-size: 9pt;"><span style="font-family: Consolas; background-color: white;">    <span style="color: green;">/* </span></span><span style="font-family: 等线; background-color: white;">输出复位信号</span><span style="color: green;"><span style="font-family: Consolas; background-color: white;">: </span><span style="font-family: 等线; background-color: white;">拉高</span><span style="font-family: Consolas; background-color: white;">&gt;100ns */
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    fd = open( SYSFS_GPIO_RST_VAL, O_RDWR );
 </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( fd == -1 )
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
 </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        printf( <span style="color: #a31515;">"ERR: Radio hard reset pin value open error.\n"<span style="color: black;"> );
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(EXIT_FAILURE);
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
 </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">while<span style="color: black;"> ( 1 )
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
 </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        write( fd, SYSFS_GPIO_RST_VAL_H, <span style="color: blue;">sizeof<span style="color: black;">(SYSFS_GPIO_RST_VAL_H) );
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        usleep( 1000000 );
 </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        write( fd, SYSFS_GPIO_RST_VAL_L, <span style="color: blue;">sizeof<span style="color: black;">(SYSFS_GPIO_RST_VAL_L) );
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        usleep( 1000000 );
 </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
 </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    close( fd );
 </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    printf( <span style="color: #a31515;">"INFO: Radio hard reset pin value open error.\n"<span style="color: black;"> );
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">return<span style="color: black;">(0);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">}
</span>

#include stdlib.h

#include stdio.h

#include string.h

#include unistd.h

#include fcntl.h /* define O_WRONLY and O_RDONLY */

/* 芯片复位引脚: P1_16 */

#define SYSFS_GPIO_EXPORT "/sys/class/gpio/export"

#define SYSFS_GPIO_RST_PIN_VAL "48"

int main()

{

int fd;

/* 打开端口/sys/class/gpio# echo 48 > export */

fd = open( SYSFS_GPIO_EXPORT, O_WRONLY );

if ( fd == -1 )

{

printf( "ERR: Radio hard reset pin open error.\n" );

return(EXIT_FAILURE);

}

write( fd, SYSFS_GPIO_RST_PIN_VAL, sizeof(SYSFS_GPIO_RST_PIN_VAL) );

close( fd );

/* 设置端口方向/sys/class/gpio/gpio48# echo out > direction */

fd = open( SYSFS_GPIO_RST_DIR, O_WRONLY );

if ( fd == -1 )

{

printf( "ERR: Radio hard reset pin direction open error.\n" );

return(EXIT_FAILURE);

}

write( fd, SYSFS_GPIO_RST_DIR_VAL, sizeof(SYSFS_GPIO_RST_DIR_VAL) );

close( fd );

/* 输出复位信号: 拉高>100ns */

fd = open( SYSFS_GPIO_RST_VAL, O_RDWR );

if ( fd == -1 )

{

printf( "ERR: Radio hard reset pin value open error.\n" );

return(EXIT_FAILURE);

}

while ( 1 )

{

write( fd, SYSFS_GPIO_RST_VAL_H, sizeof(SYSFS_GPIO_RST_VAL_H) );

usleep( 1000000 );

write( fd, SYSFS_GPIO_RST_VAL_L, sizeof(SYSFS_GPIO_RST_VAL_L) );

usleep( 1000000 );

}

close( fd );

printf( "INFO: Radio hard reset pin value open error.\n" );

return(0);

}

三、中断检测

<span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#include<span style="color: black;"> stdlib.h
</span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#include<span style="color: black;"> stdio.h
</span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#include<span style="color: black;"> string.h
</span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#include<span style="color: black;"> unistd.h
</span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#include<span style="color: black;"> fcntl.h
</span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#include<span style="color: black;"> poll.h
</span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">#define<span style="color: black;"> MSG( args ... ) printf( args )
</span></span><span style="color: green; font-size: 9pt;"><span style="font-family: Consolas; background-color: white;">/* </span><span style="font-family: 等线; background-color: white;">函数声明</span><span style="font-family: Consolas; background-color: white;"> */
</span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">static <span style="color: black;"> <span style="color: blue;">int<span style="color: black;"> gpio_export( <span style="color: blue;">int<span style="color: black;"> pin );
</span></span></span></span></span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">static<span style="color: black;"> <span style="color: blue;">int<span style="color: black;"> gpio_unexport( <span style="color: blue;">int<span style="color: black;"> pin );
</span></span></span></span></span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">static<span style="color: black;"> <span style="color: blue;">int<span style="color: black;"> gpio_direction( <span style="color: blue;">int<span style="color: black;"> pin, <span style="color: blue;">int<span style="color: black;"> dir );
</span></span></span></span></span></span></span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">static<span style="color: black;"> <span style="color: blue;">int<span style="color: black;"> gpio_write( <span style="color: blue;">int<span style="color: black;"> pin, <span style="color: blue;">int<span style="color: black;"> value );
</span></span></span></span></span></span></span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">static<span style="color: black;"> <span style="color: blue;">int<span style="color: black;"> gpio_read( <span style="color: blue;">int<span style="color: black;"> pin );
</span></span></span></span></span></span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">static<span style="color: black;"> <span style="color: blue;">int<span style="color: black;"> gpio_export( <span style="color: blue;">int<span style="color: black;"> pin )
</span></span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">{
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">char<span style="color: black;">    buffer[64];
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">int<span style="color: black;">    len;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">int<span style="color: black;">    fd;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    fd = open( <span style="color: #a31515;">"/sys/class/gpio/export"<span style="color: black;">, O_WRONLY );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( fd &lt; 0 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"Failed to open export for writing!\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(-1);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    len = snprintf( buffer, <span style="color: blue;">sizeof<span style="color: black;">(buffer), <span style="color: #a31515;">"%d"<span style="color: black;">, pin );
</span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( write( fd, buffer, len ) &lt; 0 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"Failed to export gpio!"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(-1);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    close( fd );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">return<span style="color: black;">(0);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">}
</span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">static<span style="color: black;"> <span style="color: blue;">int<span style="color: black;"> gpio_unexport( <span style="color: blue;">int<span style="color: black;"> pin )
</span></span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">{
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">char<span style="color: black;">    buffer[64];
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">int<span style="color: black;">    len;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">int<span style="color: black;">    fd;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    fd = open( <span style="color: #a31515;">"/sys/class/gpio/unexport"<span style="color: black;">, O_WRONLY );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( fd &lt; 0 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"Failed to open unexport for writing!\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(-1);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    len = snprintf( buffer, <span style="color: blue;">sizeof<span style="color: black;">(buffer), <span style="color: #a31515;">"%d"<span style="color: black;">, pin );
</span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( write( fd, buffer, len ) &lt; 0 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"Failed to unexport gpio!"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(-1);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    close( fd );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">return<span style="color: black;">(0);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">}
</span><span style="color: green; font-family: Consolas; font-size: 9pt; background-color: white;">/* dir: 0--&gt;IN, 1--&gt;OUT */
</span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">static<span style="color: black;"> <span style="color: blue;">int<span style="color: black;"> gpio_direction( <span style="color: blue;">int<span style="color: black;"> pin, <span style="color: blue;">int<span style="color: black;"> dir )
</span></span></span></span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">{
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">static<span style="color: black;"> <span style="color: blue;">const<span style="color: black;"> <span style="color: blue;">char<span style="color: black;">    dir_str[] = <span style="color: #a31515;">"in\0out"<span style="color: black;">;
 </span></span></span></span></span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">   <span style="color: blue;">char<span style="color: black;">            path[64];
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">   <span style="color: blue;">int<span style="color: black;">            fd;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    snprintf( path, <span style="color: blue;">sizeof<span style="color: black;">(path), <span style="color: #a31515;">"/sys/class/gpio/gpio%d/direction"<span style="color: black;">, pin );
</span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    fd = open( path, O_WRONLY );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( fd &lt; 0 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"Failed to open gpio direction for writing!\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(-1);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( write( fd, &amp;dir_str[dir == 0 ? 0 : 3], dir == 0 ? 2 : 3 ) &lt; 0 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"Failed to set direction!\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(-1);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    close( fd );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">return<span style="color: black;">(0);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">}
</span><span style="color: green; font-family: Consolas; font-size: 9pt; background-color: white;">/* value: 0--&gt;LOW, 1--&gt;HIGH */
</span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">static<span style="color: black;"> <span style="color: blue;">int<span style="color: black;"> gpio_write( <span style="color: blue;">int<span style="color: black;"> pin, <span style="color: blue;">int<span style="color: black;"> value )
</span></span></span></span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">{
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">static<span style="color: black;"> <span style="color: blue;">const<span style="color: black;"> <span style="color: blue;">char<span style="color: black;">    values_str[] = <span style="color: #a31515;">"01"<span style="color: black;">;
</span></span></span></span></span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">char<span style="color: black;">            path[64];
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">int<span style="color: black;">            fd;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    snprintf( path, <span style="color: blue;">sizeof<span style="color: black;">(path), <span style="color: #a31515;">"/sys/class/gpio/gpio%d/value"<span style="color: black;">, pin );
</span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    fd = open( path, O_WRONLY );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( fd &lt; 0 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"Failed to open gpio value for writing!\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(-1);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( write( fd, &amp;values_str[value == 0 ? 0 : 1], 1 ) &lt; 0 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"Failed to write value!\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(-1);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    close( fd );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">return<span style="color: black;">(0);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">}
</span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">static<span style="color: black;"> <span style="color: blue;">int<span style="color: black;"> gpio_read( <span style="color: blue;">int<span style="color: black;"> pin )
</span></span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">{
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">char<span style="color: black;">    path[64];
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">char<span style="color: black;">    value_str[3];
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">int<span style="color: black;">    fd;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    snprintf( path, <span style="color: blue;">sizeof<span style="color: black;">(path), <span style="color: #a31515;">"/sys/class/gpio/gpio%d/value"<span style="color: black;">, pin );
</span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    fd = open( path, O_RDONLY );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( fd &lt; 0 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"Failed to open gpio value for reading!\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(-1);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( read( fd, value_str, 3 ) &lt; 0 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"Failed to read value!\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(-1);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    close( fd );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">return<span style="color: black;">(atoi( value_str ) );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">}
</span><span style="color: green; font-family: Consolas; font-size: 9pt; background-color: white;">/*
</span><span style="color: green; font-size: 9pt;"><span style="font-family: Consolas; background-color: white;"> * none</span><span style="font-family: 等线; background-color: white;">表示引脚为输入，不是中断引脚</span>
</span><span style="color: green; font-size: 9pt;"><span style="font-family: Consolas; background-color: white;"> * rising</span><span style="font-family: 等线; background-color: white;">表示引脚为中断输入，上升沿触发</span>
</span><span style="color: green; font-size: 9pt;"><span style="font-family: Consolas; background-color: white;"> * falling</span><span style="font-family: 等线; background-color: white;">表示引脚为中断输入，下降沿触发</span>
</span><span style="color: green; font-size: 9pt;"><span style="font-family: Consolas; background-color: white;"> * both</span><span style="font-family: 等线; background-color: white;">表示引脚为中断输入，边沿触发</span>
</span><span style="color: green; font-family: Consolas; font-size: 9pt; background-color: white;"> * 0--&gt;none, 1--&gt;rising, 2--&gt;falling, 3--&gt;both
</span><span style="color: green; font-family: Consolas; font-size: 9pt; background-color: white;">*/
</span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">static<span style="color: black;"> <span style="color: blue;">int<span style="color: black;"> gpio_edge( <span style="color: blue;">int<span style="color: black;"> pin, <span style="color: blue;">int<span style="color: black;"> edge )
</span></span></span></span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">{
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">const<span style="color: black;"> <span style="color: blue;">char<span style="color: black;">    dir_str[] = <span style="color: #a31515;">"none\0rising\0falling\0both"<span style="color: black;">;
</span></span></span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">char<span style="color: black;">        ptr;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">char<span style="color: black;">        path[64];
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">int<span style="color: black;">        fd;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">switch<span style="color: black;"> ( edge )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">case<span style="color: black;"> 0:
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        ptr = 0;
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">break<span style="color: black;">;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">case<span style="color: black;"> 1:
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        ptr = 5;
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">break<span style="color: black;">;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">case<span style="color: black;"> 2:
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        ptr = 12;
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">break<span style="color: black;">;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">case<span style="color: black;"> 3:
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        ptr = 20;
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">break<span style="color: black;">;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">default<span style="color: black;">:
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        ptr = 0;
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    snprintf( path, <span style="color: blue;">sizeof<span style="color: black;">(path), <span style="color: #a31515;">"/sys/class/gpio/gpio%d/edge"<span style="color: black;">, pin );
</span></span></span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    fd = open( path, O_WRONLY );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( fd &lt; 0 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"Failed to open gpio edge for writing!\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(-1);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( write( fd, &amp;dir_str[ptr], strlen( &amp;dir_str[ptr] ) ) &lt; 0 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"Failed to set edge!\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(-1);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    close( fd );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">return<span style="color: black;">(0);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">}
</span><span style="color: green; font-family: Consolas; font-size: 9pt; background-color: white;">/* GPIO1_17 */
</span><span style="color: blue; font-family: Consolas; font-size: 9pt; background-color: white;">int<span style="color: black;"> main()
</span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">{
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">int<span style="color: black;">        gpio_fd, ret;
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">struct<span style="color: black;"> pollfd    fds[1];
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">char<span style="color: black;">        buff[10];
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">unsigned<span style="color: black;"> <span style="color: blue;">char<span style="color: black;">    cnt = 0;
 </span></span></span></span></span><span style="color: green; font-size: 9pt;"><span style="font-family: Consolas; background-color: white;">/* LED</span><span style="font-family: 等线; background-color: white;">引脚初始化</span><span style="font-family: Consolas; background-color: white;"> */
 </span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    gpio_export( 115 );
  </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">   gpio_direction( 115, 1 );
  </span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">   gpio_write( 115, 0 );
</span><span style="color: green; font-size: 9pt;"><span style="font-family: Consolas; background-color: white;">/*</span><span style="font-family: 等线; background-color: white;">按键引脚初始化</span><span style="font-family: Consolas; background-color: white;"> */
</span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    gpio_export( 49 );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    gpio_direction( 49, 0 );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    gpio_edge( 49, 1 );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    gpio_fd = open( <span style="color: #a31515;">"/sys/class/gpio/gpio49/value"<span style="color: black;">, O_RDONLY );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( gpio_fd &lt; 0 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"Failed to open value!\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">return<span style="color: black;">(-1);
 </span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">   }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    fds[0].fd    = gpio_fd;
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    fds[0].events    = POLLPRI;
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    ret        = read( gpio_fd, buff, 10 );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">if<span style="color: black;"> ( ret == -1 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        MSG( <span style="color: #a31515;">"read\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">while<span style="color: black;"> ( 1 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        ret = poll( fds, 1, 0 );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">if<span style="color: black;"> ( ret == -1 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">            MSG( <span style="color: #a31515;">"poll\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        <span style="color: blue;">if<span style="color: black;"> ( fds[0].revents &amp; POLLPRI )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        {
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">            ret = lseek( gpio_fd, 0, SEEK_SET );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">            <span style="color: blue;">if<span style="color: black;"> ( ret == -1 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">                MSG( <span style="color: #a31515;">"lseek\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">            ret = read( gpio_fd, buff, 10 );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">            <span style="color: blue;">if<span style="color: black;"> ( ret == -1 )
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">                MSG( <span style="color: #a31515;">"read\n"<span style="color: black;"> );
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">            gpio_write( 115, cnt++ % 2 );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">        usleep( 100000 );
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    }
</span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">    <span style="color: blue;">return<span style="color: black;">(0);
</span></span></span><span style="color: black; font-family: Consolas; font-size: 9pt; background-color: white;">} </span>

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#include stdlib.h

#include stdio.h

#include string.h

#include unistd.h

#include fcntl.h

#include poll.h

#define MSG( args ... ) printf( args )

/* 函数声明 */

static int gpio_export( int pin );

static int gpio_unexport( int pin );

static int gpio_direction( int pin, int dir );

static int gpio_write( int pin, int value );

static int gpio_read( int pin );

static int gpio_export( int pin )

{

char buffer[64];

int len;

int fd;

fd = open( "/sys/class/gpio/export", O_WRONLY );

if ( fd < 0 )

{

MSG( "Failed to open export for writing!\n" );

return(-1);

}

len = snprintf( buffer, sizeof(buffer), "%d", pin );

if ( write( fd, buffer, len ) < 0 )

{

MSG( "Failed to export gpio!" );

return(-1);

}

close( fd );

return(0);

}

static int gpio_unexport( int pin )

{

char buffer[64];

int len;

int fd;

if ( fd < 0 )

{

MSG( "Failed to open unexport for writing!\n" );

return(-1);

}

{

MSG( "Failed to unexport gpio!" );

return(-1);

}

close( fd );

return(0);

}

/* dir: 0-->IN, 1-->OUT */

static int gpio_direction( int pin, int dir )

{

static const char dir_str[] = "in\0out";

char path[64];

int fd;

snprintf( path, sizeof(path), "/sys/class/gpio/gpio%d/direction", pin );

fd = open( path, O_WRONLY );

if ( fd < 0 )

{

MSG( "Failed to open gpio direction for writing!\n" );

return(-1);

}

if ( write( fd, &dir_str[dir == 0 ? 0 : 3], dir == 0 ? 2 : 3 ) < 0 )

{

MSG( "Failed to set direction!\n" );

return(-1);

}

close( fd );

return(0);

}

/* value: 0-->LOW, 1-->HIGH */

static int gpio_write( int pin, int value )

{

static const char values_str[] = "01";

int fd;

fd = open( path, O_WRONLY );

if ( fd < 0 )

{

MSG( "Failed to open gpio value for writing!\n" );

return(-1);

}

{

MSG( "Failed to write value!\n" );

return(-1);

}

close( fd );

return(0);

}

static int gpio_read( int pin )

{

char path[64];

char value_str[3];

int fd;

fd = open( path, O_RDONLY );

if ( fd < 0 )

{

MSG( "Failed to open gpio value for reading!\n" );

return(-1);

}

if ( read( fd, value_str, 3 ) < 0 )

{

MSG( "Failed to read value!\n" );

return(-1);

}

close( fd );

return(atoi( value_str ) );

}

/*

* none表示引脚为输入，不是中断引脚

* rising表示引脚为中断输入，上升沿触发

* falling表示引脚为中断输入，下降沿触发

* both表示引脚为中断输入，边沿触发

* 0-->none, 1-->rising, 2-->falling, 3-->both

*/

static int gpio_edge( int pin, int edge )

{

const char dir_str[] = "none\0rising\0falling\0both";

char ptr;

char path[64];

int fd;

switch ( edge )

{

case 0:

ptr = 0;

break;

case 1:

ptr = 5;

break;

case 2:

ptr = 12;

break;

case 3:

ptr = 20;

break;

default:

ptr = 0;

}

snprintf( path, sizeof(path), "/sys/class/gpio/gpio%d/edge", pin );

fd = open( path, O_WRONLY );

if ( fd < 0 )

{

MSG( "Failed to open gpio edge for writing!\n" );

return(-1);

}

{

MSG( "Failed to set edge!\n" );

return(-1);

}

close( fd );

return(0);

}

/* GPIO1_17 */

int main()

{

int gpio_fd, ret;

struct pollfd fds[1];

char buff[10];

unsigned char cnt = 0;

/* LED引脚初始化 */

gpio_export( 115 );

gpio_direction( 115, 1 );

gpio_write( 115, 0 );

/*按键引脚初始化 */

gpio_export( 49 );

gpio_direction( 49, 0 );

gpio_edge( 49, 1 );

gpio_fd = open( "/sys/class/gpio/gpio49/value", O_RDONLY );

if ( gpio_fd < 0 )

{

MSG( "Failed to open value!\n" );

return(-1);

}

fds[0].fd = gpio_fd;

fds[0].events = POLLPRI;

ret = read( gpio_fd, buff, 10 );

if ( ret == -1 )

MSG( "read\n" );

while ( 1 )

{

ret = poll( fds, 1, 0 );

if ( ret == -1 )

MSG( "poll\n" );

if ( fds[0].revents & POLLPRI )

{

ret = lseek( gpio_fd, 0, SEEK_SET );

if ( ret == -1 )

MSG( "lseek\n" );

ret = read( gpio_fd, buff, 10 );

if ( ret == -1 )

MSG( "read\n" );

gpio_write( 115, cnt++ % 2 );

}

usleep( 100000 );

}

return(0);

}

转载请注明：徐自远的乱七八糟小站 » Orange PI GPIO控制详细教程

徐自远的乱七八糟小站涉及电子，网络，编程，软件使用，机械结构等等方面。

Orange PI GPIO控制详细教程

Orange PI GPIO控制详细教程

一、sysfs方式

二、文件读写例程

三、中断检测

苏ICP备18041234号-1 苏公网安备 32021402001397号

Orange PI GPIO控制 详细教程

一、sysfs方式

二、文件读写例程

三、中断检测

苏ICP备18041234号-1 苏公网安备 32021402001397号

Orange PI GPIO控制详细教程