linux 应用层使用gpio
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- 使用这个代码之前 首先确认开发版的 “/sys/class/” 目录下有gpio这个文件夹，如果没有就需要配置linux内核
/** * @author emlsyx * @email yangx_1118@163.com * @create date 2020-02-19 19:11:53 * @modify date 2020-02-19 19:11:53 * @desc [description] */ #include <stdlib.h> #include <stdio.h> #include <string.h> #include <unistd.h> #include <fcntl.h> #include <linux/poll.h> #define err_out(fmt, ...) \\ do \\ { \\ printf(fmt, ##__VA_ARGS__); \\ printf("<%s> \\"%s()\\" %d error\\n", __FILE__, __FUNCTION__, __LINE__); \\ } while (0) #define open_gpio_file(path, flag, fd) \\ do \\ { \\ fd = open(path, flag); \\ if (fd < 0) \\ { \\ err_out("\\"%s\\" open failed \\n", path); \\ return (-1); \\ } \\ } while (0); /** * @brief : gpio 导出 * @param : pin * @retval: 0 成功; -1失败 */ static int gpio_export(const int pin) { int fd, len; char buffer[64]; char path[64]; sprintf(&path[0], "/sys/class/gpio/gpio%d", pin); /* 文件不存在时，导出gpio*/ if (access(path, F_OK) != 0) { memset(path, 0, 64); sprintf(&path[0], "/sys/class/gpio/export"); open_gpio_file(path, O_WRONLY, fd); len = snprintf(buffer, sizeof(buffer), "%d", pin); if (write(fd, buffer, len) < 0) { err_out("write failed to export gpio!\\n"); return -1; } close(fd); } return 0; } /** * @brief : gpio 卸载 * @param : pin * @retval: 0 成功; -1失败 */ static int gpio_unexport(const int pin) { int fd, len; char buffer[64]; char path[64]; sprintf(&path[0], "/sys/class/gpio/gpio%d", pin); /* 文件存在时，卸载gpio*/ if (access(path, F_OK) == 0) { memset(path, 0, 64); sprintf(&path[0], "/sys/class/gpio/unexport"); open_gpio_file(path, O_WRONLY, fd); len = snprintf(buffer, sizeof(buffer), "%d", pin); if (write(fd, buffer, len) < 0) { err_out("write failed to unexport gpio!\\n"); return -1; } close(fd); } return 0; } /** * @brief : gpio 方向控制 * @param : dir 方向(in/out) * @retval: 0 成功; -1失败 */ static int gpio_direction(const int pin, const char *dir) { int fd; char path[64]; int w_len = ((dir[0] == \'i\') && (dir[1] == \'n\')) ? 2 : 3; snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/direction", pin); open_gpio_file(path, O_WRONLY, fd); if (write(fd, dir, w_len) < 0) { err_out("Failed to set direction!\\n"); return -1; } close(fd); return 0; } /** * @brief : gpio 写 * @param : 0 / 1 * @retval: 0 成功; -1失败 */ static int gpio_write(const int pin, const int value) { int fd; char path[64]; const char *val[] = {"0", "1"}; snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/value", pin); open_gpio_file(path, O_WRONLY, fd); if (write(fd, val[value], 1) < 0) { err_out("Failed to write value!\\n"); return -1; } close(fd); return 0; } /** * @brief : gpio 读 * @param : 读取的引脚值 * @retval: 返回引脚的值 0 / 1 */ static int gpio_read(const int pin) { int fd; char path[64]; char value_str[3]; snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/value", pin); open_gpio_file(path, O_RDONLY, fd); if (read(fd, value_str, 3) < 0) { err_out("Failed to read value!\\n"); return -1; } close(fd); return (atoi(value_str)); } /** * @brief : gpio 中断控制 * @param : 0 none 表示引脚为输入，不是中断引脚 * @arg : 1 rising 表示引脚为中断输入，上升沿触发 * @arg : 2 falling 表示引脚为中断输入，下降沿触发 * @arg : 3 both 表示引脚为中断输入，边沿触发 * @retval: */ static int gpio_edge(const int pin, int edge) { int fd; char path[64]; const char *dir_str[] = {"none", "rising", "falling", "both"}; if (edge > 3) { err_out("Failed edge parameter error\\n"); return -1; } snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/edge", pin); open_gpio_file(path, O_WRONLY, fd); if (write(fd, dir_str[edge], strlen(dir_str[edge])) < 0) { err_out("Failed to set edge!\\n"); return -1; } close(fd); return 0; } int main() { char buff[10], res; int led_fd, key_fd; struct pollfd fds; /* 按键led指示灯*/ gpio_export(55); gpio_direction(55, "out"); gpio_write(55, 0); /* 按键引脚初始化*/ gpio_export(70); gpio_direction(70, "in"); gpio_edge(70, 2); open_gpio_file("/sys/class/gpio/gpio70/value", O_RDONLY, key_fd); /* poll 操作的文件符号*/ fds.fd = key_fd; /* 经测试io中断产生后，正常会发送POLLPRI 这个中断，循环中必须等待这个事件*/ fds.events = POLLPRI | POLLERR; /* 真实发生的事件*/ fds.revents = 0; while (1) { int ret = poll(&fds, 1, -1); if (!ret) { err_out("poll time out\\n"); } else { if (fds.revents & POLLPRI) { gpio_write(55, gpio_read(55) ? 0 : 1); res = lseek(fds.fd, 0, SEEK_SET); /* 读取按键值*/ if (res == -1) { printf("lseek failed!\\n"); return -1; } res = read(fds.fd, buff, sizeof(buff)); if (res == -1) { perror("read failed!\\n"); return -1; } printf("fds.revents %d key value %s \\n", fds.revents, buff); } } } return 0; }
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