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Creating a Simple Hardware DriverDescription: This tutorial shows how to create a simple hardware driver that connects via serial to a Parallax RFID Card Reader.
Tutorial Level: INTERMEDIATE
This tutorial is under construction
This tutorial will show how to create a simple hardware driver for the Parallax RFID card reader that broadcasts RFID transponder tag IDs on a topic when they are detected. This information can then be used in a variety of ways by other nodes to identify people, objects or locations.
If you haven't done so already, create a directory for your repository and add it to your ROS_PACKAGE_PATH. To make the change permanent you can add the export statement to your .bashrc after it sources the setup.bash file.
$ cd ~/ros $ mkdir mylab-ros-pkg $ export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:~/ros/mylab-ros-pkg
Next create a separate stack to contain RFID related packaged.
$ cd ~/ros/mylab-ros-pkg $ roscreate-stack mylab_rfid
Next edit ~/ros/mylab-ros-pkg/mylab_rfid/stack.xml file to have the appropriate information.
<stack> <description brief="mylab_rfid">RFID Driver and Tools</description> <author>Maintained by My Robotics Lab</author> <license>BSD</license> <review status="unreviewed" notes=""/> <url>http://ros.org/wiki/mylab_rfid</url> <depend stack="ros" /> </stack>
Since we want to use libserial to talk to the serial port we need to add that as a dependency. First we can check if it defined anywhere else.
$ rosdep where_defined libserial
Since dependencies are handled at the stack level we need to edit ~/ros/mylab-ros-pkg/mylab_rfid/rosdep.yaml so that it looks like this.
libserial: ubuntu: libserial-dev debian: libserial-dev
Next we create the package for the driver. Since we will be writing it in C++, we specify roscpp as a dependency.
$ roscreate-pkg parallax_rfid roscpp
Switch to the package directory and we can begin setting up the package.
$ cd ~/ros/mylab-ros-pkg/mylab_rfid/parallax_rfid
The manifest.xml file in ~/ros/mylab-ros-pkg/mylab_rfid/parallax_rfid should look something like this.
<package> <description brief="Parallax RFID Card Reader"> Driver for Parallax 125kHz RFID Card Reader </description> <author>Me Myself</author> <license>BSD</license> <review status="unreviewed" notes=""/> <url>http://ros.org/wiki/parallax_rfid</url> <depend package="roscpp"/> <rosdep name="libserial"/> </package>
Next, wait for the rest of the tutorial to be written