Difference between revisions of "Writing a Simple Publisher and Subscriber (C++)"
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3) Run: | 3) Run: | ||
− | <nowiki>catkin_create_pkg beginner_tutorials std_msgs rospy roscpp</nowiki> | + | <nowiki> |
+ | cd ~/catkin_ws | ||
+ | catkin_create_pkg beginner_tutorials std_msgs rospy roscpp</nowiki> | ||
If errors such as "File already exist" show up, delete those files from ~/catkin_ws/src/beginner_tutorials | If errors such as "File already exist" show up, delete those files from ~/catkin_ws/src/beginner_tutorials | ||
Latest revision as of 10:35, 22 October 2014
Writing a Simple Publisher and Subscriber (C++)
1) In a terminal, move to your beginner_tutorials folder:
cd ~/catkin_ws/src/beginner_tutorials
Note: If you have a ~/catkin_ws/beginner_tutorials folder:
All changes that are done to the ~/catkin_ws/src/beginner_tutorials MUST be completed for ~/catkin_ws/beginner_tutorials as well.
2) In ~/catkin_ws/beginner_tutorials, remove all folders and files. This can be done manually using Home Folder.
3) Run:
cd ~/catkin_ws catkin_create_pkg beginner_tutorials std_msgs rospy roscpp
If errors such as "File already exist" show up, delete those files from ~/catkin_ws/src/beginner_tutorials
Writing the Publisher Node
1) Create the file talker.cpp:
gedit src/talker.cpp
2) In the gedit editor, paste all from this link. Save the file and close the editor. For information on what is inside this file, see this link. In a nutshell, it initializes the ROS system, advertise what we are doing, and finally loop what we are doing.
Writing the Subscriber Node
1) In a terminal, move to your beginner_tutorials folder:
cd ~/catkin_ws/src/beginner_tutorials
2) Create the file listener.cpp:
gedit src/listener.cpp
3) In the gedit editor, paste all from this link. Save the file and close the editor. For information on what is inside this file, see this link. In a nutshell, it initializes the ROS system, subscribes to the topic 'chatter', spin (wait for messages), when message arrives call the chatterCallback() function.
Building Nodes 1) Run:
catkin_create_pkg beginner_tutorials std_msgs rospy roscpp
This creates a CMakeLists.txt file and a Package.xml file. If there are errors such as "File does not exist", likely the cpp files created above need to be in the both of the beginner_tutorials folder.
2) Edit the CMakeList.txt file (this step should be just the one folder):
gedit beginner_tutorials/CMakeLists.txt
Add the following to the end of the file:
include_directories(include ${catkin_INCLUDE_DIRS}) add_executable(talker src/talker.cpp) target_link_libraries(talker ${catkin_LIBRARIES}) add_dependencies(talker beginner_tutorials_generate_messages_cpp) add_executable(listener src/listener.cpp) target_link_libraries(listener ${catkin_LIBRARIES}) add_dependencies(listener beginner_tutorials_generate_messages_cpp)
For a completely clean file, you can view the entire CMakeLists.txt file here
Save the file and close the editor. This should create a talker and listener files in your devel folder.
3) Navigate to your catkin workspace:
cd ~/catkin_ws
4) And make the catkin:
catkin_make