linux C编程-读串口数据-支持自定义波特率

注意：本方法包含的<asm-generic/termbits.h>和<termios.h>这两个头文件里都定义了struct termios，需将其中一个注释。

#include <stdio.h>
#include <sys/select.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <string.h>
#include <asm-generic/ioctls.h>
#include <asm-generic/termbits.h>

#define ERRLOG(msg)                                         \
    do                                                      \
    {                                                       \
        printf("%s:%s:%d\n", __FILE__, __func__, __LINE__); \
        perror(msg);                                        \
        exit(-1);                                           \
    } while (0);


// 打开串口函数
int open_serial(const char *device)
{
    int fd = open(device, O_RDWR | O_NOCTTY | O_NDELAY);
    if (fd == -1)
    {
        perror("打开串口失败");
        return -1;
    }
    // 设置为阻塞模式
    if (fcntl(fd, F_SETFL, 0) < 0)
    {
        perror("设置串口阻塞失败");
        close(fd);
        return -1;
    }
    return fd;
}
// 设置串口参数
int configure_serial(int fd, int baudrate, int databits, int stopbits, char parity)
{
    struct termios options;

    // 获取当前串口设置
    if (tcgetattr(fd, &options) != 0)
    {
        perror("获取串口属性失败");
        return -1;
    }

    // 设置输入输出波特率
    cfsetispeed(&options, B0); // 先清除波特率
    cfsetospeed(&options, B0);

    // 使用自定义波特率
    struct termios2 term2;
    if (ioctl(fd, TCGETS2, &term2) == -1)
    {
        perror("获取termios2失败");
        return -1;
    }
    term2.c_cflag &= ~CBAUD;
    term2.c_cflag |= BOTHER;
    term2.c_ispeed = baudrate;
    term2.c_ospeed = baudrate;
    if (ioctl(fd, TCSETS2, &term2) == -1)
    {
        perror("设置自定义波特率失败");
        return -1;
    }

    // 设置字符大小
    options.c_cflag &= ~CSIZE;
    switch (databits)
    {
    case 7:
        options.c_cflag |= CS7;
        break;
    case 8:
        options.c_cflag |= CS8;
        break;
    default:
        fprintf(stderr, "不支持的数据位: %d\n", databits);
        return -1;
    }

    // 设置停止位
    if (stopbits == 1)
    {
        options.c_cflag &= ~CSTOPB;
    }
    else if (stopbits == 2)
    {
        options.c_cflag |= CSTOPB;
    }
    else
    {
        fprintf(stderr, "不支持的停止位: %d\n", stopbits);
        return -1;
    }

    // 设置校验位
    switch (parity)
    {
    case 'N': // 无校验
        options.c_cflag &= ~PARENB;
        options.c_iflag &= ~INPCK;
        break;
    case 'E': // 偶校验
        options.c_cflag |= PARENB;
        options.c_cflag &= ~PARODD;
        options.c_iflag |= INPCK;
        break;
    case 'O': // 奇校验
        options.c_cflag |= PARENB;
        options.c_cflag |= PARODD;
        options.c_iflag |= INPCK;
        break;
    default:
        fprintf(stderr, "不支持的校验位: %c\n", parity);
        return -1;
    }

    // 设置串口为原始模式
    options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
    options.c_oflag &= ~OPOST;

    // 设置输入模式
    options.c_iflag &= ~(IXON | IXOFF | IXANY);

    // 设置属性生效
    if (tcsetattr(fd, TCSANOW, &options) != 0)
    {
        perror("设置串口属性失败");
        return -1;
    }

    return 0;
}

int main(int argc, char *argv[])
{
    char *device = "/dev/ttyUSB0";
    int fd = open_serial(device);
    if (fd == -1)
    {
        return EXIT_FAILURE;
    }

    int baudrate = 614400;
    int databits = 8;
    int stopbits = 1;
    char parity = 'E';

    if (configure_serial(fd, baudrate, databits, stopbits, parity) == -1)
    {
        close(fd);
        return EXIT_FAILURE;
    }

    fd_set read_fds;
    unsigned char readBuffer[1024] = {0};
// 收数据
    while (1)
    {
        FD_ZERO(&read_fds);
        FD_SET(fd, &read_fds);

        // 使用 select 等待数据
        int activity = select(fd + 1, &read_fds, NULL, NULL, NULL);
        if (activity < 0)
        {
            perror("select error");
            break;
        }
        if (FD_ISSET(fd, &read_fds))
        {
            int bytes_read = read(fd, readBuffer, sizeof(readBuffer));

            if (bytes_read > 0)
            {
                for (size_t i = 0; i < bytes_read; i++)
                {
                    printf("%02X ", readBuffer[i]);
                }
                putchar('\n');
                // printf("%s\n",readBuffer);
                memset(readBuffer, 0, sizeof(readBuffer));
            }
            // 每次读到数据存在这里readBuffer
        }
    }

    return 0;
}