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标题: 写QT程序控制LED灯的亮灭 [打印本页]

作者: scx2006114 时间: 2019-10-18 14:10
标题: 写QT程序控制LED灯的亮灭
核心板：My-IMX6-CB200-6q-2g
评估板：MY-IMX6-EK200
系统内核：Linux-3.14.52
u-boot版本：u-boot-2015.04-svn54

请问如何通过写C语言或者Qt程序控制LED的亮灭，有没有类似的教程？不是通过测试手册上面的指令控制LED的亮灭。

作者: 软件01 时间: 2019-10-19 16:24
可以参考一下下面的gpio输出和输入下降沿中断
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <poll.h>

  int gpio_open(int gpio)
  {
FILE *fp;

if ((fp = fopen("/sys/class/gpio/export", "w")) == NULL)
{
      printf("Cannot open export file.\n");
      return -1;
}
fprintf(fp, "%d", gpio);
fclose(fp);
return 0;
  }
  int gpio_direction(int gpio)
  {
   FILE *fp;
char s[50]="";
sprintf(s,"/sys/class/gpio/gpio%d/direction",gpio);
if ((fp = fopen(s, "rb+")) == NULL)
{
      printf("Cannot open %s.\n",s);
      return -1;
}
fprintf(fp, "out");
fclose(fp);
return 0;
  }

int gpio_high(int gpio)
{
   FILE *fp;
char buffer[10];
char s1[50]="";
sprintf(s1,"/sys/class/gpio/gpio%d/value",gpio);

if ((fp = fopen(s1, "rb+")) == NULL)
{
      printf("Cannot open %s.\n",s1);
      return -1;
}
strcpy(buffer,"1");
fwrite(buffer, sizeof(char), sizeof(buffer) - 1, fp);
fclose(fp);
return 0;
}

   int gpio_low(int gpio)
{
   FILE *fp;
char buffer[10];
char s1[50]="";
sprintf(s1,"/sys/class/gpio/gpio%d/value",gpio);

if ((fp = fopen(s1, "rb+")) == NULL)
{
      printf("Cannot open %s.\n",s1);
      return -1;
}
strcpy(buffer,"0");
fwrite(buffer, sizeof(char), sizeof(buffer) - 1, fp);
fclose(fp);
return 0;
}

int main(int argc, char *argv[])
{
   int fd, ret;
   char value;
   struct pollfd pfd;

gpio_open(435);
gpio_direction(435);
gpio_low(435);
system("echo \"444\" > /sys/class/gpio/export");
system("echo \"in\" > /sys/class/gpio/gpio444/direction");
system("echo \"falling\" > /sys/class/gpio/gpio444/edge");
// system("echo \"both\" > /sys/class/gpio/gpio443/edge");

fd = open("/sys/class/gpio/gpio444/value", O_RDWR);
   if (fd < 0) {
      printf("open file fail\n");
      return -1;
   }

   pfd.fd = fd;
   pfd.events = POLLPRI | POLLERR;

ret = lseek(fd, 0, SEEK_SET);
   if (ret == -1) {
      printf("lseek error\n");
      return -1;
   }
   //读取1字节
ret = read(fd, &value, 1);

   while (1) {
      /* 监听个数1，等待时间无限 */
      ret = poll(&pfd, 1, -1);
      if (ret == -1) {
         printf("poll error\n");
         return -1;
      }
      /* 监听的时间会保存在revents成员中 */
      if (pfd.revents & POLLPRI) {
         //文件指针只想文件的开头
         ret = lseek(fd, 0, SEEK_SET);
         if (ret == -1) {
               printf("lseek error\n");
               return -1;
         }
         //读取，结果为字符'0'或者‘1’
         read(fd, &value, 1);
         printf("value:%c\n", value);
/*       if (value == '0')
gpio_high(434);
      if (value == '1')
gpio_low(434); */
      }
   }

   close(fd);

   return 0;
}

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