linux 使用usb转串口模块并读串口数据

时间：2021-12-21 07:49:05

买了一个无线通信模块，在windows下还要装驱动才能读。在windows下测试无线模块没问题后，在ubantu14.2中测试怎么读串口。步骤如下：

1.查看看系统信息

dmesg | tail -f

输出如下：

[12812.940613] usb 1-9: New USB device found, idVendor=10c4, idProduct=ea60
[12812.940621] usb 1-9: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[12812.940627] usb 1-9: Product: CP2102 USB to UART Bridge Controller
[12812.940631] usb 1-9: Manufacturer: Silicon Labs
[12812.940634] usb 1-9: SerialNumber: 0001
[12812.941748] cp210x 1-9:1.0: cp210x converter detected
[12813.106603] usb 1-9: reset full-speed USB device number 5 using xhci_hcd
[12813.123424] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff88023eec6fc0
[12813.123433] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff88023eec6f80
[12813.124130] usb 1-9: cp210x converter now attached to ttyUSB0

该模块为CP2102，最后一句表示设备连接到了ttyUSB0

2.查看模块装载的情况

dmesg | grep ttyUSB0

输出
[12796.093492] usb 1-9: cp210x converter now attached to ttyUSB0
[12810.605949] cp210x ttyUSB0: cp210x converter now disconnected from ttyUSB0
[12813.124130] usb 1-9: cp210x converter now attached to ttyUSB0
表示已经装载了模块。

3.安装minicom

sudo apt-get install minicom

4.配置minicom

配置minicom

sudo minicom -s

参考博客
http://www.cnblogs.com/shishiteng/p/5801826.html
选择serial port setup
只要配置三项就行了
按E键 设置 Bps/Par/Bit 为9600（根据个人的波特率设置）
按A键，设置Serial Device为： /dev/ttyUSB0
按F键，设置Hardware Flow Control 为No

5.保存收到的数据到log文件和查看串口数据

sudo minicom
这里提示按”Ctrl+A”,再按”Z”键进入主配置目录
（1）保存收到的数据到log文件
按Ｌ进入
输入输出文件的保存路径
参考
http://www.2cto.com/os/201111/110568.html
（2）查看串口数据
启动发送就有数据显示了，并能在文件中查看数据

6.使用程序打开串口

参考
http://blog.csdn.net/specialshoot/article/details/50707965
使用minicom能够读到数据后，新建以下工程，内容如下

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include<sys/ioctl.h>
int set_opt(int,int,int,char,int);
int open_port(char* uartname)
{
int fd = open(uartname, O_RDWR|O_NOCTTY|O_NONBLOCK);
if (-1 == fd)
    {
        perror("Can't Open Serial Port");
return(-1);
    }
/*恢复串口为阻塞状态*/
if(fcntl(fd, F_SETFL, 0)<0)
     {
printf("fcntl failed!\n");
     }else{
printf("fcntl=%d\n",fcntl(fd, F_SETFL,0));
     }
/*测试是否为终端设备*/
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(int argc, char* argv[])
{
printf("hello,run ok\n");
int fd=1, read_num = 0;
char buffer[1024];
memset(buffer, 0, 1024);
char* uartname="/dev/ttyUSB0";
// if(argc < 2)
// {
// printf("usage: ./uarttest /dev/ttyUSB0 \n");
// return 0;
// }
if((fd=open_port(uartname))<0)
    {
printf("open %s is failed\n",uartname);
return 0;
    }
else{
            set_opt(fd, 115200, 8, 'N', 1);
printf("set_opt fd=%d\n",fd);

while(1){
char c=getchar();
printf("%c",c);
if('q'==c)
                    {
return 0;
                    }
                    sleep(1);
memset(buffer, 0, 1024);
                    read_num = read(fd, buffer, 1024);
printf("read_num=%d\n",read_num);
if(read_num>0){
printf("rev char=%s\n",buffer);
int num=atoi(buffer);
printf("rev int=%d\n",num);
                    }else{
printf("read error\n");
                    }
            }
          fd=close(fd);
    }
return 0;
}


int set_opt(int fd,int nSpeed, int nBits, char nEvent, int nStop)
{
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;
case 460800:
        cfsetispeed(&newtio, B460800);
        cfsetospeed(&newtio, B460800);
break;
case 921600:
printf("B921600\n");
        cfsetispeed(&newtio, B921600);
                cfsetospeed(&newtio, B921600);
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\r");
return 0;
}

编译运行提示
Can’t Open Serial Port: Permission denied
解决方法：
改变usb设备的执行权限# sudo chmod 777 /dev/ttyUSB0

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