#include
#include
#include
#include
#include
#include
#define msg(args...) printf(args)
//函式宣告
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_edge(int pin, int edge);
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);
printf("%s,%d,%d\n",buffer,sizeof(buffer),len);
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;
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 path[64];
char value_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表示引腳為輸入，不是中斷引腳
// rising表示引腳為中斷輸入，上公升沿觸發
// falling表示引腳為中斷輸入，下降沿觸發
// both表示引腳為中斷輸入，邊沿觸發
// 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;
gpio_unexport(44);
gpio_unexport(45);
//p8_12 init
gpio_export(44);
gpio_direction(44, 1);//output out
gpio_write(44, 1);
//p8_11 init
gpio_export(45);
gpio_direction(45, 0);//input in
gpio_edge(45,2);
gpio_fd = open("/sys/class/gpio/gpio45/value",o_rdonly);
if(gpio_fd < 0)
msg("failed to open value!\n");
return -1;
fds[0].fd = gpio_fd;
fds[0].events = pollpri;
while(1)
ret = read(gpio_fd,buff,10);
if( ret == -1 )
msg("read\n");
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");
//gpio_write(44, cnt++%2);
printf("**********************************\n");
usleep(5);
return 0;
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