Orange PI GPIO控制详细教程

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 > export2. 设置方向/sys/class/gpio/gpio44# echo out > direction3. 查看方向/sys/class/gpio/gpio44# cat direction4. 设置输出/sys/class/gpio/gpio44# echo 1 > value5. 查看输出值/sys/class/gpio/gpio44# cat value6. 取消导出/sys/class/gpio# echo 44 > unexport二、文件读写例程#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"#define SYSFS_GPIO_RST_DIR "/sys/class/gpio/gpio48/direction"#define SYSFS_GPIO_RST_DIR_VAL "OUT"#define SYSFS_GPIO_RST_VAL "/sys/class/gpio/gpio48/value"#define SYSFS_GPIO_RST_VAL_H "1"#define SYSFS_GPIO_RST_VAL_L "0"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#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 b uffer[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 b uffer[64];int len;int fd;fd = open( "/sys/class/gpio/unexport", O_WRONLY );if ( fd < 0 ){MSG( "Failed to open unexport for writing!\n" );return(-1);}len = snprintf( buffer, sizeof(buffer), "%d", pin );if ( write( fd, buffer, len ) < 0 ){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";char path[64];int fd;snprintf( path, sizeof(path), "/sys/class/gpio/gpio%d/value", pin );fd = open( path, O_WRONLY );if ( fd < 0 ){MSG( "Failed to open gpio value for writing!\n" );return(-1);}if ( write( fd, &values_str[value == 0 ? 0 : 1], 1 ) < 0 ){MSG( "Failed to write value!\n" );return(-1);}close( fd );return(0);}static int gpio_read( int pin ){char p ath[64];char v alue_str[3];int fd;snprintf( path, sizeof(path), "/sys/class/gpio/gpio%d/value", pin );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);}if ( write( fd, &dir_str[ptr], strlen( &dir_str[ptr] ) ) < 0 ){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);}。