dev: Add ROS 2 deployment to Pi tutorial

Signed-off-by: Ryan Friedman <25047695+Ryanf55@users.noreply.github.com>

dev/source/docs/ros.rst

@@ -68,6 +68,7 @@ ROS 2
         ROS 2 over Ethernet <ros2-over-ethernet>
         ROS 2 waypoint goal interface <ros2-waypoint-goal-interface>
         Cartographer SLAM with ROS 2 in SITL <ros2-cartographer-slam>
+        ROS 2 on Raspberry Pi <ros2-pi>
 
 
 Conclusion

dev/source/docs/ros2_pi.rst

@@ -0,0 +1,81 @@
+.. _ros2-pi:
+
+=====================
+ROS 2 on Raspberry Pi
+=====================
+
+Purpose
+=============
+
+Learn how to install the ROS onto a companion computer and run a sample ROS 2 application that communicated with ArduPilot over Micro XRCE DDS.
+For this demonstation, a Raspberry Pi Zero 2W will be used, however other Linux computers are also capable.
+
+Required Hardware
+=================
+
+* `Raspberry Pi Zero 2W <https://www.raspberrypi.com/products/raspberry-pi-zero-2-w/>`__
+* A Linux computer to flash an SD card and configure the Pi
+
+Initial Configuration
+=====================
+
+For the first section, we will follow `Ubuntu's tutorial <https://ubuntu.com/tutorials/how-to-install-ubuntu-on-your-raspberry-pi#1-overview>`__ , with specifics noted below.
+
+Use ``rpi-imager``.
+
+When selecting the operating system, we will install Ubuntu 22 Server.
+Find it in "Other general-purpose OS -> Ubuntu -> Ubuntu Server 22.04.5 LTS (64-bit) which is supported
+by `ROS 2 humble <https://www.ros.org/reps/rep-2000.html#humble-hawksbill-may-2022-may-2027>`__.
+When prompted to do "OS Customisation", select that.
+* In "General", Configure wireless LAN
+* In "Services", enable SSH
+* Save and flash the image onto the device
+
+Install the SD card, let it boot for 2 minutes, then either through a HDMI display and keyboard, or by plugging the Pi's SD card back into your computer, edit the file:
+``/etc/avahi/avahi-daemon.conf`` and change the line that has ``publish-workstation`` to ``publish-workstation=yes``.
+
+Now, put the SD card back into the Pi, boot it up with the USB, and you can now connect.
+
+
+.. code-block:: bash
+
+    # Find the address of the PI
+    avahi-resolve -n ubuntu.local
+    # SSH into it (the first time)
+    ssh ubuntu@ubuntu.local
+
+Once you SSH, create your username and password, and test you can still login, it's time to set up ROS 2.
+We'll install all the packages before it's wired into the drone.
+
+ROS 2 Install
+=============
+
+When using Ubuntu 22.04, it's easiest to install ROS 2 through binaries.
+https://docs.ros.org/en/humble/Installation/Ubuntu-Install-Debs.html
+
+First off, if you can't use ``apt update`` due to "Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 912 (unattended-upgr)",
+try removing unattended upgrades
+
+.. code-block:: bash
+
+    sudo systemctl stop unattended-upgrades
+    sudo apt-get purge unattended-upgrades
+
+When installing ROS 2, install ``ros-humble-ros-base`` and ``ros-dev-tools``.
+
+Serial Connection
+=================
+
+Now, wire a serial connection to your flight controller. Ensure your power supply is capable of powering the Pi Zero 2W.
+The simplest solution is to wire an open telemetry port.
+
+.. warning::
+
+   Do not abuse the power supply for the flight controller.
+   For robust applications, it is recommended to power non-flight-critical devices,
+   such as a Raspberry Pi, with a separate 5V power supply.
+   Although many flight controller power supplies may support the power draw of 
+   a Raspberry Pi Zero 2W, a problem on the PI can bring down the entire vehicle.
+
+.. figure:: ../images/PiZero2WTelem.png
+   :target: ../_images/PiZero2WTelem.png