Linux C控制向/sys/class/leds/blue/brightness写入1和0来模拟PWM信号的程序

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

#define LED_PATH "/sys/class/leds/blue/brightness"

int main(int argc, char *argv[])
{
int fd = open(LED_PATH, O_WRONLY);
if(fd == -1)
{
perror("Failed to open LED file");
exit(EXIT_FAILURE);
}

int i;
for(i = 0; i < 5; i++)
{
write(fd, "1", 1);
usleep(50000);
write(fd, "0", 1);
usleep(50000);
}

close(fd);
return 0;
}

相关问题

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。

Linux C控制向/sys/class/leds/blue/brightness这个GPIO端口写入1和0来实现呼吸灯的程序

以下是一个基于Linux C的呼吸灯程序，使用/sys/class/leds/blue/brightness控制GPIO端口，实现灯的呼吸效果：

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

#define LED_PATH "/sys/class/leds/blue/brightness"
#define LED_MAX_BRIGHTNESS 255

int main()
{
    int led_fd = open(LED_PATH, O_WRONLY);
    if (led_fd < 0) {
        printf("Failed to open LED file descriptor.\n");
        return -1;
    }

    // Enable breathing effect
    int breathing = 1;
    int brightness = 0;
    int delta = 5;

    while (breathing) {
        char buffer[8];
        sprintf(buffer, "%d\n", brightness);
        write(led_fd, buffer, strlen(buffer));

        if (brightness <= 0) {
            delta = 5;
        } else if (brightness >= LED_MAX_BRIGHTNESS) {
            delta = -5;
        }

        brightness += delta;

        usleep(10000); // Sleep for 10 milliseconds
    }

    close(led_fd);
    return 0;
}

该程序使用open()函数打开/sys/class/leds/blue/brightness文件并返回一个文件描述符。它使用write()函数向该文件写入一个代表灯亮度的字符串。程序启用呼吸效果，即循环增加和减少LED亮度，从而实现呼吸灯效果。最后，程序使用close()函数关闭文件描述符。