GPIO使用Sample Code

1. 编译gpio.c生成gpio。

2. 执行./gpio

3. 当echo 1 > value，读出来不是1，或者echo 0 > value，读出来不是0,则会打印一行红色字体的Log。

   gpio.c代码如下:

   #include <stdio.h>
   #include <stdlib.h>
   #include <string.h>
   #include <sys/types.h>
   #include <sys/stat.h>
   #include <sys/time.h>
   #include <fcntl.h>
   #include <unistd.h>
   BOOL gexit;
   
   int GPIO_request(int volatile num)
   {
       int gpiofd = -1;
       char buf[3];
       sprintf(buf, "%d", num);
   
       gpiofd = open("/sys/class/gpio/export", O_WRONLY);
   
       if(gpiofd == -1)
       {
           // fail to open gpio device
           printf("fail to open device!\n");
           return -1;
       }
   
       //printf("open success!\r\n");
   
       write(gpiofd, buf, sizeof(buf));
       printf("/******************************************/");
       printf("gpio_request success,pin num = %d\n", num);
   
       close(gpiofd);
       return 0;
   }
   
   int GPIO_set_direct(int volatile num, char* direct)
   {
       int fd = -1;
       char path[30];
       sprintf(path, "/sys/class/gpio/gpio%d/direction", num);
       printf("path = %s\n", path);
   
       fd = open(path, O_WRONLY);
   
       if(fd == -1)
       {
           // fail to open watchdog device
           printf("fail to device!\n");
           return -1;
       }
   
       write(fd, direct, sizeof(direct));
       //printf("gpio_direction is %s\n", direct);
   
       close(fd);
       return 0;
   }
   
   int GPIO_set_value(int volatile num, int value)
   {
       FILE* fd = NULL;
       char buf = '0';
       char path[40];
   
       //printf("num=%d\n", num);
       sprintf(&buf, "%d", value);
       snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/value", num);
   
       //printf("path = %s\n", path);
       //printf("value = %c\n", buf);
   
       fd = fopen(path, "wb");
   
       if(fd == NULL)
       {
           // fail to open device
           printf("fail to open value device!\n");
           return -1;
       }
   
       fwrite(&buf, 1, 1, fd);
       printf("gpio_set %c\n", buf);
   
       fclose(fd);
       return 0;
   }
   
   int GPIO_get_value(int volatile num)
   {
       FILE* file = NULL;
       char buf[10] = {0};
       char path[50] = {0};
       sprintf(path, "/sys/class/gpio/gpio%d/value", num);
   
       file = fopen(path, "rb");
   
       if(file == NULL)
       {
           // fail to open watchdog device
           printf("GPIO_get_value: fail to open!\n");
           return -1;
       }
   
       fseek(file, 0, SEEK_END); //文件指针转到文件末尾
       int len = ftell(file);
       rewind(file);
   
       fread(buf, 1, len, file);
       printf("GPIO_get_value:gpio_value is %s\n", buf);
   
       fclose(file);
   
       return atoi(buf);
   }
   
   int GPIO_cancel(int volatile num)
   {
       int gpiofd = -1;
       char buf[3];
       sprintf(buf, "%d", num);
   
       gpiofd = open("/sys/class/gpio/unexport", O_WRONLY);
   
       if(gpiofd == -1)
       {
           // fail to open watchdog device
           printf("has no this gpio!\n");
           return -1;
       }
   
       write(gpiofd, buf, sizeof(buf));
       printf("GPIO %d cancel!\r\n", num);
       close(gpiofd);
   
       return 0;
   }
   
   int GPIO_Read(int volatile num)
   {
       int value;
       GPIO_request(num);
       GPIO_set_direct(num, "in");
       value = GPIO_get_value(num);
   
       GPIO_cancel(num);
       return value;
   }
   
   int GPIO_Write(int volatile num, int value)
   {
       GPIO_request(num);
       GPIO_set_direct(num, "out");
       int ret = GPIO_set_value(num, value);
   
       if(ret < 0)
       {
           printf("fail to write!\n");
           return -1;
       }
   
       GPIO_cancel(num);
       return 0;
   }
   int main(int argc, char* argv[])
   {
       int gpio_num = 0,gpio_set_value=0,gpio_get_value=0;
       int ret = 0;
       if(argc == 3)
       {
           gpio_num = atoi(argv[1]);
           gpio_set_value = atoi(argv[2]);
           printf("test gpio%d.....\n",gpio_num);
           GPIO_request(gpio_num);
           GPIO_set_direct(gpio_num, "out");
           ret = GPIO_set_value(gpio_num, gpio_set_value);
           if(ret < 0)
           {
               printf("fail to write!\n");
           }
           return 0;
       }
       for(;gpio_num < 126;gpio_num++)
       {
           if(gpio_num==3 || gpio_num==2)continue; // for I6e,this is PAD_PM_UART_TX PAD_PM_UART_RX
           sleep(1);
           GPIO_request(gpio_num);
           GPIO_set_direct(gpio_num, "out");
           for(gpio_set_value=0;gpio_set_value<2;gpio_set_value++)
           {
               ret = GPIO_set_value(gpio_num, gpio_set_value);
               if(ret < 0)
               {
                   printf("fail to write!\n");
                   continue;
               }
               gpio_get_value = GPIO_get_value(gpio_num);
               if(gpio_get_value != gpio_set_value)
               {
                   printf("\033[0;31m""gpio_get_value != gpio_set_value : %d != %d\n",gpio_get_value,gpio_set_value);
                   printf("\033[0m");
               }
           }
   
           GPIO_cancel(gpio_num);
       }
   
   }
   /*
   void help(void)
   {
       printf("./gpio num direct value\n");
       printf("num   :the number of gpio you want to request. \n");
       printf("direct:the direction of gpio.\n");
       printf("value :if the direction was set to 'out',the value should be set '0 or 1'\n");
       printf("for example:\n");
       printf("   ./gpio 13 in     :set gpio13 as in\n");
       printf("   ./gpio 13 out 0  :set gpio13 as out and set value to 0\n");
   }
   
   void* getGpioValue(void* argv)
   {
       int num, value;
       num = *(int*)argv;
   
       while(gexit)
       {
           value = GPIO_get_value(num);
           printf("getGpioValue is %d\n", value);
       }
   
       return NULL;
   }
   
   int main(int argc, char* argv[])
   {
   #if 1
       int num, value;
       pthread_t pthread;
   
       if(argc < 3)
       {
           help();
           exit(0);
       }
   
       num = atoi(argv[1]);
       GPIO_request(num);
   
       if(strcmp(argv[2], "out") == 0)      //配置端口为输出
       {
           value = atoi(argv[3]);
           GPIO_set_direct(num, "out");
           GPIO_set_value(num, value);
       }
       else if(strcmp(argv[2], "in") == 0)  //配置端口输入
       {
           //创建线程，轮询该接口的值，并输出。
           gexit = 1;
           pthread_create(&pthread, NULL, getGpioValue, (void*)&num);
       }
       else
       {
           printf("argv[2]  %d is not ok!\r\n", num);
           exit(0);
       }
   
       while(1)
       {
           char ch;
           scanf("%c", &ch);
   
           if('q' == ch || 'Q' == ch)
               break;
       }
   
       gexit = 0;
   
       GPIO_cancel(num);
   
   #else
       int volatile num, value;
   
       printf("GPIO read........\n");
       num = atoi(argv[1]);
       value = atoi(argv[2]);
       GPIO_Read(num);
   
       sleep(2);
       printf("\n\n");
       printf("GPIO write........\n");
       GPIO_Write(num, value);
   
   #endif
   
       return 0;
   }
   */