c语言如何串口发送0x550x550x550x550x550x550x550x55

可以使用以下代码来实现：

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

int main()
{
    int fd;
    struct termios options;

    // 打开串口
    fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);
    if (fd == -1)
    {
        perror("open");
        exit(EXIT_FAILURE);
    }

    // 设置串口参数
    tcgetattr(fd, &options);
    cfsetispeed(&options, B9600);
    cfsetospeed(&options, B9600);
    options.c_cflag |= (CLOCAL | CREAD);
    options.c_cflag &= ~PARENB;
    options.c_cflag &= ~CSTOPB;
    options.c_cflag &= ~CSIZE;
    options.c_cflag |= CS8;
    options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
    options.c_iflag &= ~(IXON | IXOFF | IXANY);
    options.c_oflag &= ~OPOST;
    options.c_cc[VMIN] = 1;
    options.c_cc[VTIME] = 0;
    tcsetattr(fd, TCSANOW, &options);

    // 发送数据
    unsigned char data[] = {0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55};
    write(fd, data, sizeof(data));

    // 关闭串口
    close(fd);

    return 0;
}

该代码先打开串口设备文件`/dev/ttyS0`，然后配置串口参数，最后发送数据`0x550x550x550x550x550x550x550x55`。注意，串口参数需要根据实际硬件进行设置。