Linux读，写Arduino串行

Question

我正在尝试从c ++程序写入Arduino串行。如何在C++程序中设置波特率？当arduino设置为9600时，通信似乎有效，但是当我更改它时失败，正如预期的那样。(所以 9600 是默认值？使用命令查看输出： 屏幕/dev/ttyUSBx 115200 使用示例程序在Arduino上回显所有内容：

* serial_echo.pde
* ----------------- 
* Echoes what is sent back through the serial port.
*
* http://spacetinkerer.blogspot.com
*/
int incomingByte = 0;    // for incoming serial data
void setup() {
Serial.begin(115200);    // opens serial port, sets data rate to 9600 bps
}
void loop() {
// send data only when you receive data:
if (Serial.available() > 0) ;
// read the incoming byte:
incomingByte = Serial.read();
// say what you got:
Serial.print((char)incomingByte);
}

C++代码为：

#include <iostream>
#include <stdio.h>
#include <string>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
using namespace std;
string comArduino(string outmsg = " hello"){
#define comports_size 3
static int fd_ard;
static bool init = false;
//char buffer[256];
if(!init){
string comports[] = { "/dev/ttyUSB0","/dev/ttyUSB1","/dev/ttyUSB2" };
for(int i = 0; i < comports_size; i++){
fd_ard = open(comports[i].c_str(), O_RDWR | O_NOCTTY | O_NDELAY);
if (fd_ard != -1) {
cout<<"connected to "<<comports[i]<<endl;
init = true;
break;
}
else{
perror ("open");
}
if(i == (comports_size - 1)){
cout<<"can't connect to arduino [ ER ]n"<<endl;
return "";
}
}
}
int Er = write(fd_ard,outmsg.c_str(),strlen(outmsg.c_str()));
if(Er < strlen(outmsg.c_str())){
perror ("write ");
init = false;
}
else
cout<<"write ok"<<endl;
return "";
}
int main(){
while(1){
comArduino();
sleep(1);
}
}

编辑：需要在open()后添加以下行以正确配置串行：

struct termios PortConf;
// write port configuration, as ' stty -F /dev/ttyUSB0 -a ' returned after opening the port with the arduino IDE.
tcgetattr(fd_ard, &PortConf);                           // Get the current attributes of the Serial port
PortConf.c_cflag = 0;                                 //set cflag
PortConf.c_cflag |= (CS8 | HUPCL | CREAD | CLOCAL);
PortConf.c_iflag = 0;                                 //set iflag
//PortConf.c_iflag &= ~(ISIG | ICANON | IEXTEN);
PortConf.c_oflag = 0;                                 //set oflag
PortConf.c_oflag |= (ONLCR | CR0 | TAB0 | BS0 | VT0 | FF0); //NR0 is supposed to be set, but won't compile
//PortConf.c_oflag &= ~(OPOST);
PortConf.c_lflag = 0;                                 //set lflag
//PortConf.c_lflag &= ~(ECHO | ECHOE);
PortConf.c_cc[VMIN]  = 0;
PortConf.c_cc[VTIME] = 0;
cfsetispeed(&PortConf,B115200);                       // Set Read  Speed as 115200                       
cfsetospeed(&PortConf,B115200);                       // Set Write Speed as 115200 
if((tcsetattr(fd_ard,TCSANOW,&PortConf)) != 0){       // Set the attributes to the termios structure
printf("Error while setting attributes n");
return "";
}

Answer 1

您需要使用 termios 结构设置正在使用的任何端口的波特率。

使用"man termios"获取有关termios结构的更多信息

所以对于开始需要添加

#include <termios.h> 

到代码的顶部。

稍后当您打开端口时：

fd_ard = open(comports[i].c_str(), O_RDWR | O_NOCTTY | O_NDELAY);

您需要访问术语结构并对其进行修改以满足您的需求

struct termios SerialPortSettings;  // Create the structure                          
tcgetattr(fd_ard, &SerialPortSettings); // Get the current attributes of the Serial port

然后，设置波特率

cfsetispeed(&SerialPortSettings,B115200); // Set Read  Speed as 115200                       
cfsetospeed(&SerialPortSettings,B115200); // Set Write Speed as 115200                       

然后提交更改

if((tcsetattr(fd_ard,TCSANOW,&SerialPortSettings)) != 0) // Set the attributes to the termios structure
printf("Error while setting attributes n");

还有许多其他东西可以为流量控制、规范模式等设置，这可能会影响数据的发送和接收方式。请参阅手册页，或参阅 此说明 通用终端界面