LINUX下串口通訊開發

 摘要：

1.開啟串口函數open_port()中要實現的函數：
(1)open("/dev/ttys0",O_RDWR | O_NOCTTY | O_NDELAY);/*開啟串口0*/
(2)fcntl(fd,F_SETFL,0)/*恢複串口為阻塞狀態*/
(3)isatty(STDIN_FILENO) /*測試是否為中斷裝置 非0即是中斷裝置*/

2.配置串口參數函數set_opt()中要實現的函數:
(1)儲存原先有串口配置
tcgetattr(fd,&oldtio);

(2)先將新串口配置清0
bzore(&newtio,sizeof(newito));

(3)啟用選項CLOCAL和CREAD 並設定資料位元大小
newtio.c_cflag |=CLOCAL | CREAD;
newtio.c_cflag &= ~CSIZE;
newtio.c_cflag |=CS8;

(4)設定同位
奇數同位:
newtio.c_cflag |= PARENB;
newtio.c_cflag |= PARODD;
newtio.c_iflag |= (INPCK | ISTRIP);
偶校正:
newtio.c_iflag |= (INPCK | ISTRIP);
newtio.c_cflag |= PAREND;
newtio.c_cflag &= ~PARODD;
無同位：
newtio.c_cflag &= ~PARENB;

(5) 設定停止位
newtio.c_cflag &= ~CSTOPB; /*停止位為1*/
newtio.c_cflag |= CSTOPB;/*停止位為0*/

(6)設定傳輸速率:
cfsetispeed(&newtio,B115200);
cfsetospeed(&newtio,B115200);

(7)設定等待時間和最小接受字元:
newtio.c_cc[VTIME] = 0;
newtio.c_cc[VMIN] = 0;

(8)處理為接收字元:
tcflush(fd,TCIFLUSH);

(9)啟用新配置:
tcsetattr(fd,TCSANOW,&newtio);
3.讀寫串口
write(fd,buff,8);
read(fd,buff,8);

常式：

#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>
int set_opt(int fd,int nSpeed, int nBits, char nEvent, int nStop)
{
/* 五個參量 fd開啟檔案 speed設定傳輸速率 bit資料位元設定   neent同位位元 stop停止位 */
    struct termios newtio,oldtio;
    if ( tcgetattr( fd,&oldtio) != 0) {
        perror("SetupSerial 1");
        return -1;
    }
    bzero( &newtio, sizeof( newtio ) );
    newtio.c_cflag |= CLOCAL | CREAD;
    newtio.c_cflag &= ~CSIZE;
    switch( nBits )
    {
    case 7:
        newtio.c_cflag |= CS7;
    break;
    case 8:
        newtio.c_cflag |= CS8;
    break;
    }
    switch( nEvent )
    {
    case 'O':
        newtio.c_cflag |= PARENB;
        newtio.c_cflag |= PARODD;
        newtio.c_iflag |= (INPCK | ISTRIP);
        break;
    case 'E':
        newtio.c_iflag |= (INPCK | ISTRIP);
        newtio.c_cflag |= PARENB;
        newtio.c_cflag &= ~PARODD;
        break;
    case 'N':
        newtio.c_cflag &= ~PARENB;
        break;
    }
switch( nSpeed )
    {
    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 115200:
        cfsetispeed(&newtio, B115200);
        cfsetospeed(&newtio, B115200);
        break;
    default:
        cfsetispeed(&newtio, B9600);
        cfsetospeed(&newtio, B9600);
        break;
    }
    if( nStop == 1 )
        newtio.c_cflag &= ~CSTOPB;
    else if ( nStop == 2 )
    newtio.c_cflag |= CSTOPB;
    newtio.c_cc[VTIME] = 0;
    newtio.c_cc[VMIN] = 0;
    tcflush(fd,TCIFLUSH);
    if((tcsetattr(fd,TCSANOW,&newtio))!=0)
    {
        perror("com set error");
        return -1;
    }
    printf("set done!\n");
    return 0;
}
int open_port(int fd,int comport)
{
/* fd 開啟串口 comport表示第幾個串口 */
    char *dev[]={"/dev/ttyS0","/dev/ttyS1","/dev/ttyS2"};
    long vdisable;
    if (comport==1)
    {    fd = open( "/dev/ttyS0", O_RDWR|O_NOCTTY|O_NDELAY);
        if (-1 == fd){
            perror("Can't Open Serial Port");
            return(-1);
        }
        else
            printf("open ttyS0 .....\n");
    }
    else if(comport==2)
    {    fd = open( "/dev/ttyS1", O_RDWR|O_NOCTTY|O_NDELAY);

    if (-1 == fd){
        perror("Can't Open Serial Port");
            return(-1);
        }
        else
            printf("open ttyS1 .....\n");
    }
    else if (comport==3)
    {
        fd = open( "/dev/ttyS2", O_RDWR|O_NOCTTY|O_NDELAY);
        if (-1 == fd){
            perror("Can't Open Serial Port");
            return(-1);
        }
        else
            printf("open ttyS2 .....\n");
    }
    if(fcntl(fd, F_SETFL, 0)<0)
        printf("fcntl failed!\n");
    else
        printf("fcntl=%d\n",fcntl(fd, F_SETFL,0));
    if(isatty(STDIN_FILENO)==0)
        printf("standard input is not a terminal device\n");
    else
        printf("isatty success!\n");
    printf("fd-open=%d\n",fd);
    return fd;
}
int main(void)
{
    int fd;
    int nread,i;
    char buff[]="Hello\n";
    if((fd=open_port(fd,1))<0){
        perror("open_port error");
        return;
    }
    if((i=set_opt(fd,115200,8,'N',1))<0){
    perror("set_opt error");
        return;
    }
    printf("fd=%d\n",fd);
//    fd=3;
    nread=read(fd,buff,8);
    printf("nread=%d,%s\n",nread,buff);
    close(fd);
    return;

}

我自己的程式：

/////////////////////////////////////////////////////////////////////////////////////////

#ifndef _COM_H
#define _COM_H

#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>

int set_opt(int fd,int nSpeed, int nBits, char nEvent, int nStop);
int open_port(int fd,int comport);
unsigned char uart_cmd(unsigned char *buffer,int tx, int rx);

#endif

/////////////////////////////////////////////////////////////////////////////////////////////////////////

#include "com.h"

//使用開發板的con2(con0,con1,con2)

 

int set_opt(int fd,int nSpeed, int nBits, char nEvent, int nStop)
{
/* 五個參量 fd開啟檔案 speed設定傳輸速率 bit資料位元設定   neent同位位元 stop停止位 */
    struct termios newtio,oldtio;
    if ( tcgetattr( fd,&oldtio) != 0) {
        perror("SetupSerial 1");
        return -1;
    }
    bzero( &newtio, sizeof( newtio ) );
    newtio.c_cflag |= CLOCAL | CREAD;
    newtio.c_cflag &= ~CSIZE;
newtio.c_oflag &= ~(ONLCR | OCRNL); //
newtio.c_iflag &= ~(IXON | IXOFF | IXANY);    //
    switch( nBits )
    {
    case 7:
        newtio.c_cflag |= CS7;
    break;
    case 8:
        newtio.c_cflag |= CS8;
    break;
    }
    switch( nEvent )
    {
    case 'O':
        newtio.c_cflag |= PARENB;
        newtio.c_cflag |= PARODD;
        newtio.c_iflag |= (INPCK | ISTRIP);
        break;
    case 'E':
        newtio.c_iflag |= (INPCK | ISTRIP);
        newtio.c_cflag |= PARENB;
        newtio.c_cflag &= ~PARODD;
        break;
    case 'N':
        newtio.c_cflag &= ~PARENB;
        break;
    }
switch( nSpeed )
    {
    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 115200:
        cfsetispeed(&newtio, B115200);
        cfsetospeed(&newtio, B115200);
        break;
    default:
        cfsetispeed(&newtio, B9600);
        cfsetospeed(&newtio, B9600);
        break;
    }
    if( nStop == 1 )
        newtio.c_cflag &= ~CSTOPB;
    else if ( nStop == 2 )
    newtio.c_cflag |= CSTOPB;
    newtio.c_cc[VTIME] =5; //測試時該大一點
    newtio.c_cc[VMIN] = 0;//set min read byte!
    tcflush(fd,TCIFLUSH);
    if((tcsetattr(fd,TCSANOW,&newtio))!=0)
    {
        perror("com set error");
        return -1;
    }
    printf("set done!\n");
    return 0;
}
int open_port(int fd,int comport)
{
/* fd 開啟串口 comport表示第幾個串口 */
    char *dev[]={"/dev/ttySAC0","/dev/ttySAC1","/dev/ttySAC2"};
    long vdisable;
    if (comport==1)
    {    fd = open( "/dev/ttySAC0", O_RDWR|O_NOCTTY|O_NDELAY);
        if (-1 == fd){
            perror("Can't Open Serial Port");
            return(-1);
        }
        else
            printf("open ttySAC0 .....\n");
    }
    else if(comport==2)
    {    fd = open( "/dev/ttySAC1", O_RDWR|O_NOCTTY|O_NDELAY);

    if (-1 == fd){
        perror("Can't Open Serial Port");
            return(-1);
        }
        else
            printf("open ttySAC1 .....\n");
    }
    else if (comport==3)
    {
        fd = open( "/dev/ttySAC2", O_RDWR|O_NOCTTY|O_NDELAY);
        if (-1 == fd){
            perror("Can't Open Serial Port");
            return(-1);
        }
        else
            printf("open ttySAC2 .....\n");
    }
    if(fcntl(fd, F_SETFL, 0)<0)
        printf("fcntl failed!\n");
    else
        printf("fcntl=%d\n",fcntl(fd, F_SETFL,0));
    if(isatty(STDIN_FILENO)==0)
        printf("standard input is not a terminal device\n");
    else
        printf("isatty success!\n");
    printf("fd-open=%d\n",fd);
    return fd;
}

//我的應用程式函數
unsigned char uart_cmd(unsigned char *buffer,int tx, int rx)
{
int fd;
int i;
int nread=0;
int nwrite=0;
unsigned char mybuffer[520],buffer1[520];
if(( fd=open_port(fd,3)) < 0)//使用開發板的con2
{
   perror("open_port error");
   return -1;
}

if(( i=set_opt(fd,115200,8,'N',1) ) < 0)
{
   perror("set_opt error");
   return -1;
}

if(( nwrite=write(fd,buffer,tx)) != tx)
{
   perror("write error");
   return -1;
}
printf("nwrite=%d\n",nwrite);

for(i=0;i<rx;i++)//read only one byte once,loop for rx times!
{
   if((nread=read(fd,mybuffer+i,1)) != 1)
   {
    perror("read error");
    return -1;
   }
}
mybuffer[rx]='\0';

strncpy(buffer,mybuffer,rx+1);

close(fd);
return 0;
}