rosserial for VEX Cortex

This package contains everything needed to run rosserial on the VEX Cortex, on the PROS Kernel.

Requirements

• Software:
  1. Linux (Only tested on Ubuntu 18.04LTS) (possible on windows with a Linux virtual machine, provided there is USB support)
  2. ROS installed on Linux (Only tested on ROS Melodic) - installation guide.
  3. PROS installed on Linux - installation guide
• Hardware:
  1. VEX essentials:
     • VEX Cortex
     • VEX Joystick
     • VEXnet keys
     • VEX Competition battery
     • VEX Programming Cable
  2. (optional, for debugging) a USB-serial adapter
  3. (optional, for debugging) Three Male-Male jumper wires for USB-serial adapter

Table Of Contents

• Setup
• Examples
  • Hello World Example
  • Keyboard or Android Phone Driving Example
  • Alternative Joystick Example
• Physical Serial Connections
• Generating Custom Messages
• Limitations
• Speed
• Troubleshooting

Setup

This setup requires knowledge of entering commands into a Linux terminal.

Note: it is possible to follow along with this guide without understanding basic ROS constructs (such as workspaces, projects, rosrun, roslaunch, and catkin_make). However, in order to work with ROS beyond the examples in this project, you will need to learn about the ROS framework itself. See the ROS documentation, getting-started, and tutorials pages for more information.

ROS Workspace

This workspace is used to generate a PROS project, and then help the Cortex interact with ROS using that generated project.

Notice the first source command below. This includes ROS commands into the terminal (such as catkin_make), so it will come first in most of the terminal commands in this setup process. Make sure you replace melodic with your corresponding ROS version name, if it is not melodic (e.g. kinetic).

Open up a terminal, and enter:

source /opt/ros/melodic/setup.bash
mkdir -p ~/ros-vex-workspace/src; cd ~/ros-vex-workspace/src
git clone https://github.com/ros-drivers/rosserial.git
cd ..; catkin_make; catkin_make install

Next, generate a PROS project, which has the code that runs on the Cortex. The project can exist anywhere (it does NOT need to be inside the ROS workspace).

source ~/ros-vex-workspace/install/setup.bash
rosrun rosserial_vex_cortex genscript.sh ~/path/to/prosproject

Examples

These examples are made to run out-of-the-box, and they made to be proof-of-concepts of what ROS can provide. ROS allows standardized messages to be sent to and from the Cortex and an outside computer, which allows for all kinds of ideas and projects to be organized with messages!

To understand what is going on with the example code, look at the tutorials for the sister project, Rosserial Arduino. There are some differences between the two projects (namely, in the PROS c++ code, global scope is not allowed).

Set up the physical download connection by plugging in the VEX Programming cable to the computer and the joystick, and then pluging the VEXnet keys into the Cortex and the joystick. This connection serves as BOTH the downloading channel AND the serial connection, so leave the programming cable plugged in! (to alter the connection to use something else, see physical serial connections). Between downloads, power-cycle the Joystick and Cortex for optimal usage.

Hello World Example

source ~/your-workspace-name/install/setup.bash
cd ~/path/to/prosproject
pros make upload; roslaunch rosserial_vex_cortex hello_world.launch

If everything is working properly, you should see “hello world” messages in the terminal!

Keyboard or Android Driving Example

This example showcases an integrated demo with a VEX EDR Robot, such as the clawbot, and an alternative method of control: a keyboard! Open up “src/twistdrive.cpp” and modify the motor control code, to specify how you want to control your robot’s drive . Modify src/opcontrol.cpp in your generated PROS project to include the twistdrive.cpp file instead of the helloworld.cpp file. Then, open a terminal and run the following:

source ~/your-workspace-name/install/setup.bash
cd /path/to/prosproject
pros make clean; pros make upload; roslaunch rosserial_vex_cortex minimal_robot.launch

Android phones can now control this robot.

File truncated at 100 lines see the full file

\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^ Changelog for package rosserial_vex_cortex \^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^\^ 0.8.0 (2018-10-11) ------------------* VEX Cortex Usage improvements and VEX V5 Support (#385) * Re-attempting rosserial for VEX Cortex (#380) * Contributors: CanyonTurtle

0.7.7

• README fixes
• started tagging versions
• initial was wrong version number, fixed.