linux 串口编程

在这里 附上linux 串口编程的 代码，仅供自己学习查找

#include<termios>
struct termios
{
   unsigned short c_iflag;  输入模式标志
   unsigned short c_oflag;  输出模式标志
   unsigned short c_cflag;  控制模式标志
   unsigned short c_lflag;  本地模式标志
   unsigned char c_line;    线路规程
   unsigned char c_cc[NCC]; 控制特征
   speed_t c_ispeed;         输入速度
   speed_ c_ospeed;          输出速度
}

/* uart_api.h */
/* 串口配置函数 */
int set_com_config(int fd,int baud_rate,
                    int data_bits, char parity, int stop_bits)
{
    struct termios new_cfg,old_cfg;
    int speed;

    /*保存并测试现有串口参数设置，在这里如果串口号等出错，会有相关的出错信息*/
    if  (tcgetattr(fd, &old_cfg)  !=  0)
    {
        perror("tcgetattr");
        return -1;
    }
    new_cfg = old_cfg;
    cfmakeraw(&new_cfg); /* 配置为原始模式 */
    new_cfg.c_cflag &= ~CSIZE;
    /*设置波特率*/
      switch (baud_rate)
      {
          case 2400:
        {
            speed = B2400;
        }
        break;
          case 4800:
        {
            speed = B4800;
        }
        break;
          case 9600:
        {
            speed = B9600;
        }
        break;
          case 19200:
        {
            speed = B19200;
        }
        break;
          case 38400:
        {
            speed = B38400;
        }
        break;

        default:
        case 115200:
        {
            speed = B115200;
        }
        break;
      }
    cfsetispeed(&new_cfg, speed);
    cfsetospeed(&new_cfg, speed);

    switch (data_bits) /*设置数据位*/
    {
        case 7:
        {
            new_cfg.c_cflag |= CS7;
        }
        break;

        default:
        case 8:
        {
            new_cfg.c_cflag |= CS8;
        }
        break;
      }

      switch (parity) /*设置奇偶校验位*/
      {
        default:
        case 'n':
        case 'N':
        {
            new_cfg.c_cflag &= ~PARENB;
            new_cfg.c_iflag &= ~INPCK;
        }
        break;

        case 'o':
        case 'O':
        {
            new_cfg.c_cflag |= (PARODD | PARENB);
            new_cfg.c_iflag |= INPCK;
        }
        break;

        case 'e':
        case 'E':
        {
            new_cfg.c_cflag |= PARENB;
            new_cfg.c_cflag &= ~PARODD;
            new_cfg.c_iflag |= INPCK;
        }
        break;

        case 's':  /*as no parity*/
        case 'S':
        {
            new_cfg.c_cflag &= ~PARENB;
            new_cfg.c_cflag &= ~CSTOPB;
        }
        break;
    }

    switch (stop_bits) /*设置停止位*/
    {
        default:
        case 1:
        {
            new_cfg.c_cflag &=  ~CSTOPB;
        }
        break;

        case 2:
        {
            new_cfg.c_cflag |= CSTOPB;
        }
    }

    /*设置等待时间和最小接收字符*/
    new_cfg.c_cc[VTIME]  = 0;
    new_cfg.c_cc[VMIN] = 1;
    tcflush(fd, TCIFLUSH); /*处理未接收字符*/
    if ((tcsetattr(fd, TCSANOW, &new_cfg)) != 0) /*激活新配置*/
    {
        perror("tcsetattr");
        return -1;
    }
    return 0;
}

/*打开串口函数*/
int open_port(int com_port)
{
    int fd;
#if (COM_TYPE == GNR_COM)  /* 使用普通串口 */
    char *dev[] = {"/dev/ttyS0", "/dev/ttyS1", "/dev/ttyS2"};
#else /* 使用USB转串口 */
    char *dev[] = {"/dev/ttyUSB0", "/dev/ttyUSB1", "/dev/ttyUSB2"};
#endif
    if ((com_port < 0) || (com_port > MAX_COM_NUM))
    {
        return -1;
    }
    /* 打开串口 */
    fd = open(dev[com_port - 1], O_RDWR|O_NOCTTY|O_NDELAY);
    if (fd < 0)
    {
            perror("open serial port");
            return(-1);
    }

    if (fcntl(fd, F_SETFL, 0) < 0) /*恢复串口为阻塞状态*/
    {
        perror("fcntl F_SETFL\n");
    }

    if (isatty(fd) == 0) /*测试打开的文件是否为终端设备*/
    {
        perror("This is not a terminal device");
    }
    return fd;
}

/* com_writer.c */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include "uart_api.h"
int main(void)
{
    int fd;
    char buff[BUFFER_SIZE];
    if((fd = open_port(HOST_COM_PORT)) < 0) /* 打开串口 */
    {
        perror("open_port");
        return 1;
    }
    if(set_com_config(fd, 115200, 8, 'N', 1) < 0) /* 配置串口 */
    {
        perror("set_com_config");
        return 1;
    }
    do
    {
        printf("Input some words(enter 'quit' to exit):");
        memset(buff, 0, BUFFER_SIZE);
        if (fgets(buff, BUFFER_SIZE, stdin) == NULL)
        {
            perror("fgets");
            break;
        }
        write(fd, buff, strlen(buff));
    } while(strncmp(buff, "quit", 4));
      close(fd);
      return 0;
}

/* com_reader.c */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include "uart_api.h"

int main(void)
{
    int fd;
    char buff[BUFFER_SIZE];

    if((fd = open_port(TARGET_COM_PORT)) < 0) /* 打开串口 */
    {
        perror("open_port");
        return 1;
    }
    if(set_com_config(fd, 115200, 8, 'N', 1) < 0) /* 配置串口 */
    {
        perror("set_com_config");
        return 1;
    }

    do
    {
        memset(buff, 0, BUFFER_SIZE);
        if (read(fd, buff, BUFFER_SIZE) > 0)
        {
            printf("The received words are : %s", buff);
        }
    } while(strncmp(buff, "quit", 4));
      close(fd);
      return 0;
}

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