uart使用Sample Code

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <errno.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>
#include <stdlib.h>
#include <pthread.h>
int fd=-1;
pthread_t RX_pthread=NULL;
pthread_t TX_pthread=NULL;
char exit_flag=0;
void display_help()
{
        printf("Usage: ./test_ttyS0 [-n number] [-b baudrate] [-h]\n\n");
        printf("\t-h: Display help info\n");
        printf("\t-b: select baudrate\n");
        printf("\t\t0:4800, 1:9600, 2:115200\n");
        printf("\t-n: select tty port\n");
        printf("\t\t0:ttyS0, 1:ttyS1, 2:ttyS2\n");
}
void open_uart(char *file)
{
        fd =open(file,O_RDWR|O_NOCTTY|O_NDELAY);

        if(fd==-1){
            printf("Benis:open %s fail\n",file);
            return; 
        }       
        if(fcntl(fd,F_SETFL,0)<0){
            printf("Benis:fcntl faild!\n"); 
        }
        isatty(STDIN_FILENO);
}
void init_uart(int baudrate_cmd)
{
        struct termios opt;

        tcgetattr(fd,&opt);
        switch(baudrate_cmd)
        {
            case 0: 
                cfsetispeed(&opt,B4800);
                cfsetospeed(&opt,B4800);
                printf("Benis:baudrate = 4800 \n");
                break;
            case 1:
                cfsetispeed(&opt,B9600);
                cfsetospeed(&opt,B9600);
                printf("Benis:baudrate = 9600 \n");
                break;
            case 2:
                cfsetispeed(&opt,B115200);
                cfsetospeed(&opt,B115200);
                printf("Benis:baudrate = 115200 \n");
                break;
        }

        opt.c_cflag &= ~CSIZE;
        opt.c_cflag |= CS8;
        opt.c_cflag |= CLOCAL|CREAD;
        opt.c_cflag &= ~PARENB;
        opt.c_iflag &= ~INPCK;
        opt.c_cflag &= ~CSTOPB;
        opt.c_cc[VTIME]=0;
        opt.c_cc[VMIN]=0;
        tcflush(fd,TCIOFLUSH);
        tcsetattr(fd,TCSANOW,&opt);
}
void close_uart(){
    if(fd!=-1)
        close(fd);  
}

void * rx_func(void * argv)
{
    char rec_buf[64];
    while(exit_flag!=1)
    {
        memset(rec_buf,0,sizeof(rec_buf));
        if(read(fd,rec_buf,sizeof(rec_buf))>0)
            printf("Benis rec:%s",rec_buf);         
    }
    return;
}
void * tx_func(void * argv)
{
    char ch;
    char tx_buf[2];
    while((ch = getchar()) != 'Q')
    {
        sprintf(tx_buf,"%c",ch);
        write(fd,tx_buf,1);
    }
    exit_flag=1;
    return;
}
int main(int argc , char *argv[])
{

        int result;
        int baudrate_opt=-1,tty_port=-1;
        char file_name[20];

        while((result=getopt(argc,argv,"hn:b:"))!=-1)
        {
            switch(result)
            {
                case 'n':
                    tty_port=atoi(optarg);
                    if(tty_port>2)
                    {
                        printf("tty port argument error!\n");
                        return -1   ;
                    }
                    break;
                case 'b':
                    baudrate_opt=atoi(optarg);
                    if(baudrate_opt>2)
                    {
                        printf("baudrate argument error!\n");
                        return -1   ;
                    }

                    break;
                case 'h':
                    display_help();
                    return 0;   
                    break;          
                default:
                    display_help();
                    return 0;           
                    break;
            }   
        }
        memset(file_name,0,sizeof(file_name));
        sprintf(file_name,"%s%d","/dev/ttyS",tty_port);
        printf("Benis:file name is %s\n",file_name);
        open_uart(file_name);
        init_uart(baudrate_opt);

        write(fd,"Benis:uart0 send ......\n",25);

        pthread_create(&RX_pthread,NULL,rx_func,NULL);
        pthread_create(&TX_pthread,NULL,tx_func,NULL);

        pthread_join(RX_pthread,NULL);
        pthread_join(TX_pthread,NULL);
        close_uart();
        return 0;
}