Linux C控制向/sys/class/leds/blue/brightness写入1和0来实现一个简单的呼吸灯

下面是一个简单的Linux C代码，使用PWM模拟呼吸灯效果，将1和0写入/sys/class/leds/blue/brightness文件来控制LED灯的开关：

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>

#define LED_PATH "/sys/class/leds/blue/brightness"
#define MAX_BRIGHTNESS 255
#define MIN_BRIGHTNESS 0
#define DELAY_US 10000

int main()
{
    int fd = open(LED_PATH, O_WRONLY);
    if (fd < 0) {
        perror("Open LED failed");
        return EXIT_FAILURE;
    }

    int brightness = MIN_BRIGHTNESS;
    int dir = 1; // 1 for increasing, -1 for decreasing

    while (1) {
        char buf[5];
        sprintf(buf, "%d", brightness);
        write(fd, buf, sizeof(buf)); // write brightness to LED file

        brightness += dir;
        if (brightness > MAX_BRIGHTNESS) {
            dir = -1;
        } else if (brightness < MIN_BRIGHTNESS) {
            dir = 1;
        }

        usleep(DELAY_US); // sleep for a while
    }

    close(fd);
    return 0;
}

这个程序使用PWM模拟呼吸灯效果，每次循环改变LED灯的亮度，最大值为255，最小值为0，延时10毫秒后再次循环实现呼吸灯效果。可以通过Ctrl+C来终止程序。