Linux下应用层串口功能的实现

转自：http://blog.csdn.net/sunrier/article/details/7661289


//serialport.h

/*************************************************************
    FileName : serialport.h
    FileFunc : 定义头文件
    Version  : V0.1
    Author   : Sunrier
    Date     : 2012-06-13
    Descp    : Linux下实现串口库
*************************************************************/
#ifndef   _SERIALPORT_H_
#define   _SERIALPORT_H_

#ifdef __cplusplus
extern "C" {
#endif

int open_port(int iPortNumber);
int set_port(int fd,int iBaudRate,int iDataSize,char cParity,int iStopBit);
int read_port(int fd,void *buf,int iByte);
int write_port(int fd,void *buf,int iByte);
int close_port(int fd);

#ifdef __cplusplus
}
#endif

#endif

 

 

//serialport.c

/*************************************************************
    FileName : serialport.c
    FileFunc : 定义实现文件
    Version  : V0.1
    Author   : Sunrier
    Date     : 2012-06-13
    Descp    : Linux下实现串口库
*************************************************************/
/*#include "serialport.h"*/
#include
#include
#include
#include
#include

int open_port(int iPortNumber)
{
    int fd = -1;
    char *pDev[]={"/dev/ttyS0","/dev/ttyS1","/dev/ttyS2","/dev/ttyS3",
                                "/dev/ttyS4","/dev/ttyS5","/dev/ttyS6","/dev/ttyS7",
                                "/dev/ttyS8","/dev/ttyS9","/dev/ttyS10","/dev/ttyS11"};

    switch( iPortNumber )
    {
        case    1:
        case    2:
        case    3:
        case    4:
        case    5:
        case  6:
        case  7:
        case  8:
        case  9:
        case  10:
        case  11:
        case  12:
                        fd = open(pDev[iPortNumber-1],O_RDWR|O_NOCTTY|O_NDELAY);
                        if( fd<0 )
                        {
                            perror("Can't Open Serial Port !");
                            return (-1);
                        }
                        else
                        {
                            printf("Open ttyS%d ......\n",iPortNumber-1);
                        }
                        break;
        default:
                        /*perror("Don't exist iPortNumber !");*/
                        printf("Don't exist iPortNumber%d under /dev/? !\n",iPortNumber);
                        return (-1);
    }

    if( fcntl(fd,F_SETFL,0)<0 )/*恢复串口的状态为阻塞状态，用于等待串口数据的读入*/
    {
        printf("fcntl failed !\n");
        return (-1);
    }
    else
    {
        printf("fcntl = %d !\n",fcntl(fd,F_SETFL,0));
    }

    /*测试打开的文件描述符是否应用一个终端设备，以进一步确认串口是否正确打开*/
    if( !isatty(STDIN_FILENO) )
    {
        printf("Standard input isn't a terminal device !\n");
        return (-1);
    }
    else
    {
        printf("It's a serial terminal device!\n");
    }

    printf("open_port file ID= %d !\n",fd);

    return fd;

}

int set_port(int fd,int iBaudRate,int iDataSize,char cParity,int iStopBit)
{
    int iResult = 0;
    struct termios oldtio,newtio;


    iResult = tcgetattr(fd,&oldtio);/*保存原先串口配置*/
    if( iResult )
    {
        perror("Can't get old terminal description !");
        return (-1);
    }


    bzero(&newtio,sizeof(newtio));
    newtio.c_cflag |= CLOCAL | CREAD;/*设置本地连接和接收使用*/

    /*设置输入输出波特率*/
    switch( iBaudRate )
    {
        case 2400:
                            cfsetispeed(&newtio,B2400);
                            cfsetospeed(&newtio,B2400);
                            break;
        case 4800:
                            cfsetispeed(&newtio,B4800);
                            cfsetospeed(&newtio,B4800);
                            break;
        case 9600:
                            cfsetispeed(&newtio,B9600);
                            cfsetospeed(&newtio,B9600);
                            break;
        case 19200:
                            cfsetispeed(&newtio,B19200);
                            cfsetospeed(&newtio,B19200);
                            break;
        case 38400:
                            cfsetispeed(&newtio,B38400);
                            cfsetospeed(&newtio,B38400);
                            break;
        case 57600:
                            cfsetispeed(&newtio,B57600);
                            cfsetospeed(&newtio,B57600);
                            break;
        case 115200:
                            cfsetispeed(&newtio,B115200);
                            cfsetospeed(&newtio,B115200);
                            break;
        case 460800:
                            cfsetispeed(&newtio,B460800);
                            cfsetospeed(&newtio,B460800);
                            break;
        default     :
                            /*perror("Don't exist iBaudRate !");*/
                            printf("Don't exist iBaudRate %d !\n",iBaudRate);
                            return (-1);
    }

    /*设置数据位*/
    newtio.c_cflag &= (~CSIZE);
    switch( iDataSize )
    {
        case    7:
                        newtio.c_cflag |= CS7;
                        break;
        case    8:
                        newtio.c_cflag |= CS8;
                        break;
        default:
                        /*perror("Don't exist iDataSize !");*/
                        printf("Don't exist iDataSize %d !\n",iDataSize);
                        return (-1);
    }

    /*设置校验位*/
    switch( cParity )
    {
        case    'N':                    /*无校验*/
                            newtio.c_cflag &= (~PARENB);
                            break;
        case    'O':                    /*奇校验*/
                            newtio.c_cflag |= PARENB;
                            newtio.c_cflag |= PARODD;
                            newtio.c_iflag |= (INPCK | ISTRIP);
                            break;
        case    'E':                    /*偶校验*/
                            newtio.c_cflag |= PARENB;
                            newtio.c_cflag &= (~PARODD);
                            newtio.c_iflag |= (INPCK | ISTRIP);
                            break;
        default:
                            /*perror("Don't exist cParity  !");*/
                            printf("Don't exist cParity %c !\n",cParity);
                            return (-1);
    }

    /*设置停止位*/
    switch( iStopBit )
    {
        case    1:
                        newtio.c_cflag &= (~CSTOPB);
                        break;
        case    2:
                        newtio.c_cflag |= CSTOPB;
                        break;
        default:
                        /*perror("Don't exist iStopBit !");*/
                        printf("Don't exist iStopBit %d !\n",iStopBit);
                        return (-1);
    }

    newtio.c_cc[VTIME] = 0; /*设置等待时间*/
    newtio.c_cc[VMIN] = 0;  /*设置最小字符*/
    tcflush(fd,TCIFLUSH);       /*刷新输入队列(TCIOFLUSH为刷新输入输出队列)*/
    iResult = tcsetattr(fd,TCSANOW,&newtio);    /*激活新的设置使之生效,参数TCSANOW表示更改立即发生*/

    if( iResult )
    {
        perror("Set new terminal description error !");
        return (-1);
    }

    printf("set_port success !\n");

    return 0;
}

int read_port(int fd,void *buf,int iByte)
{
    int iLen = 0;
    if( !iByte )
    {
        printf("Read byte number error !\n");
        return iLen;
    }

    iLen = read(fd,buf,iByte);

    return iLen;
}

int write_port(int fd,void *buf,int iByte)
{
    int iLen = 0;
    if( !iByte )
    {
        printf("Write byte number error !\n");
        return iLen;
    }

    iLen = write(fd,buf,iByte);

    return iLen;
}


int close_port(int fd)
{
    int iResult = -1;

    iResult = close(fd);

    return iResult;
}

 

 

//demo.c

/*************************************************************
    FileName : demo.c
    FileFunc : 测试串口应用
    Version  : V0.1
    Author   : Sunrier
    Date     : 2012-06-13
    Descp    : Linux下实现串口库
*************************************************************/
#include
#include
#include "serialport.h"

int main(int argc,char *argv[])
{
    int iResult = -1;
    int fd = -1,iCommPort,iBaudRate,iDataSize,iStopBit;
    char cParity;
    int iLen;
    char szBuffer[30];

    iCommPort = 1;
    fd = open_port(iCommPort);
    if( fd<0 )
    {
        perror("open_port error !");
        return 1;
    }

    iBaudRate = 115200;
    iDataSize = 8;
    cParity = 'N';
    iStopBit = 1;
    iResult = set_port(fd,iBaudRate,iDataSize,cParity,iStopBit);
    if( iResult<0 )
    {
        perror("set_port error !");
        return 1;
    }

    printf("fd = %d \n",fd);

    //memset(szBuffer,0,sizeof(szBuffer));
    //iLen = read_port(fd,szBuffer,5);
    iLen = write_port(fd,"Hello",5);
    memset(szBuffer,0,sizeof(szBuffer));
    iLen = read_port(fd,szBuffer,5);
    if( iLen>0 )
        //printf("Write byte success !\n");
    //szBuffer[iLen+1] = '\0';
    printf("iLen =  %d ,szBuffer = %s \n",iLen,szBuffer);

    return 0;
}