ROS下樹莓派USB串口通信

    做工程時需要在樹莓派進行串口通信。具體爲接收到某個ROS的topic數據後，向串口下發數據。代碼編寫有兩種方法。

    方法一：藉助serial庫

          1、運行環境爲ubuntu，首先安裝serial庫：

sudo apt-get install serial

          2、配置編寫的package中的CMakeLists.txt

                在find_package中添加serial；

          3、給設備的USB端口權限；

          4、代碼範例：

               manipulator_ros_serial.cpp

#include <ros/ros.h>
#include <string>
#include <serial/serial.h>
#include <std_msgs/Int64.h>

#define sBUFFERSIZE 7
unsigned char s_buffer[sBUFFERSIZE]; 

using namespace std;

serial::Serial ser;

//trans different serial cmds according to different action_cmd(joystick button)
void write_action_cmd(const std_msgs::Int64& action_cmd){
	memset(s_buffer,0,sizeof(s_buffer));
	if( 1 == action_cmd.data ){
		s_buffer[0] = 0x55;
		s_buffer[1] = 0x55;
		s_buffer[2] = 0x05;
		s_buffer[3] = 0x06;
		s_buffer[4] = 0x01;
		s_buffer[5] = 0x01;
		s_buffer[6] = 0x00;
		//std::cout<<"cmd has been received and published!!!"<<&std::endl;
		}
	ser.write(s_buffer,sBUFFERSIZE);
	}

int main(int argc, char** argv){
	ros::init(argc, argv, "manipulator_ros_serial_node");
	ros::NodeHandle nh;
	ros::NodeHandle nh_private("~");
	
	std::string serial_port_;
	int baudrate_;
	nh_private.param<std::string>("serial_port", serial_port_, "/dev/ttyUSB0");
	nh_private.param<int>("baudrate", baudrate_, 9600);
	
	std::cout<<"The serial port is  "<<serial_port_<<"   ..."<<&std::endl;
	std::cout<<"The baudrate is  "<<baudrate_<<"  ..."<<&std::endl;
	ros::Subscriber write_sub = nh.subscribe("joystick/manipulator", 1000, write_action_cmd);
	try
	{
		ser.setPort(serial_port_);
		ser.setBaudrate(baudrate_);
		serial::Timeout to = serial::Timeout::simpleTimeout(1000);
		ser.setTimeout(to);
		ser.open();
		}
	catch(serial::IOException& e){
		ROS_ERROR_STREAM("Unable to open port!!!");
		return -1;
		}
		
	if(ser.isOpen()){
		ROS_INFO_STREAM("Serial Port initialized...");
		}
	else{
		return -1;
		}
		

    ros::Rate loop_rate(50); 
    while(ros::ok()) { 
       ros::spinOnce(); 
       loop_rate.sleep(); 
     } 

}

      5、USB端口號和波特率都能通過launch文件配置。 

       manipulator_ros_serial.launch

<launch>
    <node pkg="manipulator_ros_serial" name="manipulator_ros_serial" type="manipulator_ros_serial" output="screen">
      <param name="serial_port" type="string" value="/dev/ttyUSB0" />
      <param name="baudrate" type="int" value="9600" />
    </node>
</launch>

  

方法二：藉助boost

      1、運行環境爲raspbian，raspbian沒有serial庫；

      2、代碼範例

           manipulator_ros.h

#ifndef MANIPULATOR_SERIAL_H_
#define MANIPULATOR_SERIAL_H_
#include <ros/ros.h>
#include <boost/asio.hpp>
#include <boost/bind.hpp> 
#include <std_msgs/Int64.h>
#include <string>

boost::asio::io_service io;
boost::asio::serial_port sp(io);

namespace manipulator_serial_namespace{
class ManipulatorSerial{
	public:
	      ManipulatorSerial();
	      ~ManipulatorSerial();
	      
	      ros::Subscriber write_sub;
	      
	      //boost::asio::io_service io;
	      
	      void write_action_cmd(const std_msgs::Int64& action_cmd);
	  };
	}

#endif

       manipulator_serial.cpp

#include <manipulator_serial/manipulator_serial.h>

#define sBUFFERSIZE 7
unsigned char s_buffer[sBUFFERSIZE];

using namespace std;
using namespace  boost::asio;

namespace manipulator_serial_namespace{
	ManipulatorSerial::ManipulatorSerial(){
		ros::NodeHandle nh;
	    ros::NodeHandle nh_private("~");
	
	    std::string serial_port_;
	    int baudrate_;
	    nh_private.param<std::string>("serial_port", serial_port_, "/dev/ttyUSB0");
	    nh_private.param<int>("baudrate", baudrate_, 9600);
	
	    std::cout<<"The serial port is  "<<serial_port_<<"   ..."<<&std::endl;
	    std::cout<<"The baudrate is  "<<baudrate_<<"  ..."<<&std::endl;
	    
	    sp.open(serial_port_);
	   
	   write_sub = nh.subscribe("joystick/manipulator", 1000, &ManipulatorSerial::write_action_cmd, this);
	   ros::spin();
	}
	
	ManipulatorSerial::~ManipulatorSerial(){}
	
	void ManipulatorSerial::write_action_cmd(const std_msgs::Int64& action_cmd){
		memset(s_buffer,0,sizeof(s_buffer));
	    if( 1 == action_cmd.data ){
		    s_buffer[0] = 0x55;
		    s_buffer[1] = 0x55;
		    s_buffer[2] = 0x05;
		    s_buffer[3] = 0x06;
		    s_buffer[4] = 0x01;
		    s_buffer[5] = 0x01;
		    s_buffer[6] = 0x00;
		//std::cout<<"cmd has been received and published!!!"<<&std::endl;
		}

	       boost::asio::write(sp, boost::asio::buffer(s_buffer));  
	}
} 

int main(int argc, char** argv) {
	::ros::init(argc, argv, "manipulator_serial_node");
	::ros::start();
	manipulator_serial_namespace::ManipulatorSerial a;
	::ros::shutdown();
}

      5、USB端口號和波特率都能通過launch文件進行配置。

    manipulator_serial.launch

<launch>
    <node pkg="manipulator_serial" name="manipulator_serial" type="manipulator_serial" output="screen">
      <param name="serial_port" type="string" value="/dev/ttyUSB0" />
      <param name="baudrate" type="int" value="9600" />
    </node>
</launch>