RIOT-ROS2

This project enables ROS2 to run on microcontrollers using the RIOT Operating System.

Architecture

ROS2 is composed of several layers. Some have been modified to be able to run on microcontroller. Here is a summary of the main difference between the ROS2 stack and the RIOT-ROS2 stack :

Layers	ROS2	RIOT-ROS2
RCLC (ROS Client Library for C)	API only	implemented, following the API
RCL (ROS Client Library)	implemented	timer.c modified
RMW (ROS MiddleWare)	Based on DDS	2 implementations : ndn-riot and emcute
rosidl	DDS, introspection	custom, serialisation based on cbor

Examples

All examples should be able to handle any RMW implementation (see Usage).

std_msgs::String

• talker_c
• listener_c

std_msgs::Int32

• pub_int32_c
• sub_int32_c

Usage

Requirements

Only Linux (preferred) and OSX (missing features) are supported.

Ubuntu

sudo apt install cmake git python3-pip python3-empy g++-multilib
pip3 install vcstool

If your arm-none-eabi-gcc is too old (< gcc 5) :

sudo add-apt-repository ppa:team-gcc-arm-embedded/ppa
sudo apt-get update
sudo apt install gcc-arm-embedded

Others

Please, follow the requirements for ros2 official installation instructions.

Get the sources

mkdir -p ~/ros2_riot_ws/src
cd ~/ros2_riot_ws
wget https://raw.githubusercontent.com/astralien3000/riot-ros2/master/riot-ros2.repos
vcs import src < riot-ros2.repos
(cd src/ros2/riot/ && git submodule update --init)

First build phase

ROS2 and RIOT have 2 very different build systems. To be able to use them together, you need to build applications in 2 steps : using Ament, as a ROS2 user would normally do, and then compiling each application for it's target microcontroller with RIOT's Makefiles.

First phase :

./src/ament/ament_tools/scripts/ament.py build --symlink-install

Second build phase

Linux example : NDN

First, setup the tap interface :

./install/RIOT/dist/tools/tapsetup/tapsetup

On a first terminal :

(cd install/talker_c && make PORT=tap0 all term)

On a second terminal :

(cd install/listener_c && make PORT=tap1 all term)

Linux example : MQTT

Usage of MQTT in RIOT

Setup the tap interface :

./install/RIOT/dist/tools/tapsetup/tapsetup
sudo ip a a fec0:affe::1/64 dev tapbr0

Download, compile and run the broker :

git clone https://github.com/eclipse/mosquitto.rsmb.git
(cd mosquitto.rsmb/rsmb/src/ && make)
./mosquitto.rsmb/rsmb/src/broker_mqtts ~/ros2_riot_ws/src/ros2/riot/broker.conf

On a second terminal :

(cd install/talker_c && make RMW=rmw_mqtt PORT=tap0 MYADDR=fec0:affe::2 all term)

On a third terminal :

(cd install/listener_c && make RMW=rmw_mqtt PORT=tap1 MYADDR=fec0:affe::3 all term)

Troubleshooting

If this command fails :

> ./RIOT/dist/tools/tapsetup/tapsetup
creating tapbr0
RTNETLINK answers: File exists

Maybe it's because you already called it. It is not supposed to be called twice.

Try :

./RIOT/dist/tools/tapsetup/tapsetup -d