按键，检测高低电平的底层操作

按键，检测高低电平的底层操作

int GPIO_getGpioVal(int gpio) { char file[256]; int fd; int val = -1; char c; sprintf(file, "/sys/class/gpio/gpio%d/value", gpio); fd = open(file, O_RDONLY); if (fd < 0) { syslog(LOG_ERR, "Failed to open GPIO %d node!\n", gpio); return -1; } if (read(fd, &c, 1) < 0) { syslog(LOG_ERR, "Failed to get from GPIO %d node!\n", gpio); } val = (c == '1') ? GPIO_HIGH : GPIO_LOW; close(fd); return val; } // 间隔多长时间读一次电平呢 #define TICKS_INTERVAL 5 // 5ms读一次电平值