关于串口的知识这里就不累赘了，看着多又烦，搞这个的都懂串口，不多废话了！！
进入正题！！
某宝很多这种模块，有各种型号的(例如ch340)，这里要说说了 选哪种合适
打开ubutnu的命令行
$lsmod | grep usbserial
usbserial 45056 2 cp210x,ch341
查看自己电脑有那些驱动比如我电脑就可以买上面型号的模块ch340的也可以
$ dmesg
输出相关信息，部分信息如下：
[ 429.184170] usb 6-1: new full-speed USB device number 3 using uhci_hcd
[ 429.345937] usb 6-1: New USB device found, idVendor=1a86, idProduct=7523
[ 429.345944] usb 6-1: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[ 429.345948] usb 6-1: Product: USB2.0-Ser!
[ 429.368123] usbcore: registered new interface driver usbserial
[ 429.368396] usbcore: registered new interface driver usbserial_generic
[ 429.368875] usbserial: USB Serial support registered for generic
[ 429.374125] usbcore: registered new interface driver ch341
[ 429.374143] usbserial: USB Serial support registered for ch341-uart
[ 429.374165] ch341 6-1:1.0: ch341-uart converter detected
[ 429.386851] usb 6-1: ch341-uart converter now attached to ttyUSB0
ID信息与lsusb检测到的一致，ch341-uart converter now attached to ttyUSB0 成功驱动，端口为ttyUSB0！！（很重要，后面的程序中需要，还有minicom也需要设置）
$ sudo apt-get install minicom
等待安装成功，然后用sudo minicom -s 设置minicom的端口对应到ttyUSB0（对应使用dmesg命令看到的信息）。
出现配置菜单：
选择“Serial port setup”，出现串口配置菜单：
输入A，修改serial device 由/Dev/tty0修改为/dev/ttyusb0，波特率等修改为115200 8N1。
enter 后 save setup as dfl
Welcome to minicom 2.7
OPTIONS: I18n
Compiled on Feb 7 2016, 13:37:27.
Port /dev/ttyUSB0, 14:06:56
Press CTRL-A Z for help on special keys
上面就是命令模式了
输入你想发送的数据就可以了，当然也可以在上面收到串口发来数据！
但是！！！可能你看不到你发送的数据，（ctrl A 后按下E选择回显）这样你就可以看到你发送的数据了！！！
ctrl A 后按下Q是退出minicom，打开minicom就在命令行下输入minicom就可以打开了
/
//Author: CSDN Maizidian
//Serial communication under ubutnu, data sending and receiving
/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#define BAUDRATE B115200 ///Baud rate : 115200
#define DEVICE "/dev/ttyUSB0"//Set your port number
int nFd = 0;
struct termios stNew;
struct termios stOld;
//Open Port & Set Port
int SerialInit()
{
nFd = open(DEVICE, O_RDWR|O_NOCTTY|O_NDELAY);
if(-1 == nFd)
{
perror("Open Serial Port Error!\n");
return -1;
}
if( (fcntl(nFd, F_SETFL, 0)) < 0 )
{
perror("Fcntl F_SETFL Error!\n");
return -1;
}
if(tcgetattr(nFd, &stOld) != 0)
{
perror("tcgetattr error!\n");
return -1;
}
stNew = stOld;
cfmakeraw(&stNew);//Set the terminal to raw mode, in which all input data is processed in bytes
//set speed
cfsetispeed(&stNew, BAUDRATE);//115200
cfsetospeed(&stNew, BAUDRATE);
//set databits
stNew.c_cflag |= (CLOCAL|CREAD);
stNew.c_cflag &= ~CSIZE;
stNew.c_cflag |= CS8;
//set parity
stNew.c_cflag &= ~PARENB;
stNew.c_iflag &= ~INNPCK;
//set stopbits
stNew.c_cflag &= ~CSTOPB;
stNew.c_cc[VTIME]=0; //Specify the minimum number of characters to be read
stNew.c_cc[VMIN]=1; //Specify the waiting time for reading the first character, the unit of time is n*100ms
//Assuming VTIME=0 is set, the read() operation is blocked indefinitely when no character is input
tcflush(nFd,TCIFLUSH); //Clear the terminal's unfinished input/output requests and data.
if( tcsetattr(nFd,TCSANOW,&stNew) != 0 )
{
perror("tcsetattr Error!\n");
return -1;
}
return nFd;
}
int main(int argc, char **argv)
{ int i;
int nRet = 0;
char *sendmsg="Wheat";
char buf[5];
if( SerialInit() == -1 )
{
perror("SerialInit Error!\n");
return -1;
}
bzero(buf, SIZE);
while(1)
{ sleep(1);
write(nFd,sendmsg,sizeof(sendmsg));//Send data to serial port
printf("%s\n",sendmsg);
/serial port receiving part
nRet = read(nFd, buf, SIZE);
if(-1 == nRet)
{
perror("Read Data Error!\n");
break;
}
if(0 < nRet)
{
buf[nRet] = 0;
printf("Recv Data: %s\n", buf);
}
/
}
close(nFd);
return 0;
}