ROS Raspberry Pi Demo

References

• Raspberry Pi 3 Ubuntu Mate Xenial 16.04 with ROS Kinetic image
• ROS motor controller node for Adafruit motor HAT IE 2348
• Adafruit motor HAT specs
• Adafruit motor HAT documentation
• Adafruit configuring I2C on Raspberry Pi
• ROS Tutorials

Motor Hat Node Installation

These steps have been completed for the catkin_ws dir. I'm starting from scratch for completeness and I don't want to mess up my working catkin_ws

Create the Workspace

 cd
 mkdir -p catkin_demo/src
 cd catkin_demo/
 ls
 catkin_make
 ls
 cd src

Download the motor hat SW

 git clone https://github.com/matpalm/ros-motorhat-node

Rename the directory

It is less confusing if the motor hat directory matches the project name. The project name is in CMakeLists.txt.

 ls
 more ros-motorhat-node/CMakeLists.txt
 mv ros-motorhat-node/ motor_hat

Build the motor hat node

 cd ..
 catkin_make
 ls devel/lib/motor_hat/

Setup the .bashrc file

Add the following to your ~/.bashrc

 source /home/ubuntu/catkin_demo/devel/setup.bash

Execution

Demo the ROS installation.

terminal 1

 roscore

terminal 2

 cd catkin_ws/
 source devel/setup.bash 
 rosrun motor_hat motor_hat_node 

terminal 3

 rosnode list
 rostopic list
 rostopic echo cmd

terminal 4

 cd catkin_ws/
 source devel/setup.bash
 rosrun motor_hat stop.py 
 rosrun motor_hat on.py 

TBD - QUESTION - Why isn't the message often not received by the motor_hat_node?

Code Inspection

The next line can be added to ~/.bashrc.

 source ~/catkin_ws/devel/setup.bash
 
 roscd hat_node
 pwd
 cd src
 ls

Look at the code

 emacs on.py&
 emacs motor_hat_node_cpp&

If emacs isn't installed use nano.

 nano on.py

References

• ROS on Raspberry Pi
• tf