Setting Up Raspberry Pi

Navio+ Autopilot Expansion

Kevin Angstadt

angstadt@umich.edu

University of Michigan

***THIS PAGE IS STILL A WORK IN PROGRESS***

Introduction

This tutorial describes the process of configuring the Raspberry Pi as a quadcopter autopilot using the Navi+ daughter card. The initial configuration (flashing of the MicroSD card) was tested using Mac OS X 10.11.1. Commands may vary from system to system.

Required Hardware

Raspberry Pi 2 Model B and MicroSD card (for example, this bundle)
Navio+, GPS antenna, and Wire pack (available here)
Micro USB cable and power source

Note: Additional parts are needed for the quadcopter frame; however, this tutorial focuses on the installation of software on the Raspberry Pi.

Set Up Raspberry Pi

Download the real-time Raspbian image from EMLID here.

Determine the mount point of the MicroSD card. For example, use df -h. For me, this was /dev/disk2.

df -h
Filesystem      Size   Used  Avail Capacity  iused   ifree %iused  Mounted on
/dev/disk1     233Gi  211Gi   22Gi    91% 55321127 5657687   91%   /
devfs          330Ki  330Ki    0Bi   100%     1142       0  100%   /dev
map -hosts       0Bi    0Bi    0Bi   100%        0       0  100%   /net
map auto_home    0Bi    0Bi    0Bi   100%        0       0  100%   /home
/dev/disk2s1    30Gi  2.4Mi   30Gi     1%        0       0  100%   /Volumes/NO NAME

Ensure that the MicroSD card is unmounted, but not ejected.
```
diskutil unmount "NO NAME"
```

Write the image to the MicroSD card. I use pv to monitor the copy, but this is not necessary.

dd if=~/Downloads/emlid-raspberrypi2-raspbian-rt-20150401.img | pv | sudo dd of=/dev/rdisk2 bs=1m

Boot the Raspberry Pi using the MicroSD card. The username is pi and the password is raspberry.

***From this point forward, all commands are executed on the Raspberry Pi***

Update the installed packages.

sudo apt-get update && sudo apt-get dist-upgrade

Reboot the Raspberry Pi. Verify that the real-time kernel is in use.

uname -a 
Linux navio-rpi 3.18.9-rt5-v7+ #1 SMP PREEMPT RT Thu Mar 26 10:31:34 UTC 2015 armv7l GNU/Linux

Install GCC 4.8

Edit the sources list.
```
sudo nano /etc/apt/sources.list
```

Make sure the file contains all of the following listings.

deb http://mirrordirector.raspbian.org/raspbian/ wheezy main contrib non-free rpi
deb http://archive.raspbian.org/raspbian wheezy main contrib non-free rpi
# Source repository to add
deb-src http://archive.raspbian.org/raspbian wheezy main contrib non-free rpi
deb http://mirrordirector.raspbian.org/raspbian/ jessie main contrib non-free rpi
deb http://archive.raspbian.org/raspbian jessie main contrib non-free rpi
# Source repository to add
deb-src http://archive.raspbian.org/raspbian jessie main contrib non-free rpi

Open the preferences file.
```
sudo nano /etc/apt/preferences
```

Insert the following lines.

Package: *
Pin: release n=wheezy
Pin-Priority: 900
Package: *
Pin: release n=jessie
Pin-Priority: 300
Package: *
Pin: release o=Raspbian
Pin-Priority: 200

Update the package list.
```
sudo apt-get update
```
Install gcc/g++ 4.8 from the jessie repositories.
```
sudo apt-get install -t jessie gcc-4.8 g++-4.8
```

Set the default compiler to be gcc 4.8.

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.6 20
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 50
sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.6 20
sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.8 50
sudo update-alternatives --install /usr/bin/arm-linux-gnueabihf-gcc arm-linux-gnueabihf-gcc /usr/bin/gcc-4.6 20
sudo update-alternatives --install /usr/bin/arm-linux-gnueabihf-gcc arm-linux-gnueabihf-gcc /usr/bin/gcc-4.8 50
sudo update-alternatives --install /usr/bin/arm-linux-gnueabihf-g++ arm-linux-gnueabihf-g++ /usr/bin/g++-4.6 20
sudo update-alternatives --install /usr/bin/arm-linux-gnueabihf-g++ arm-linux-gnueabihf-g++ /usr/bin/g++-4.8 50

Clone and Build ArduCopter

Clone the source.

cd
  git clone git://github.com/diydrones/ardupilot.git

Check out the Copter-3.3 branch

cd ardupilot/ArduCopter
  git checkout Copter-3.3

Build the source.
```
make -j4 navio
```

Move the executable out of the source code.

sudo mkdir -p /opt/apm/bin
  sudo cp ArduCopter.elf /opt/apm/bin/ArduCopter-quad

Make a symbolic link in the executable path.

sudo ln -s /opt/apm/bin/ArduCopter-quad /usr/local/bin/ArduCopter-quad

References

Building for NAVIO+ on RPi2. Accessed 2015-12-21. http://dev.ardupilot.com/wiki/building-for-navio-on-rpi2

GCC 4.8 On Raspberry Pi Wheezy. Accessed 2015-12-21. https://somewideopenspace.wordpress.com/2014/02/28/gcc-4-8-on-raspberry-pi-wheezy

Real-time Linux for RPi2. Accessed 2015-12-21. http://docs.emlid.com/navio/Downloads/Real-time-Linux-RPi2

Last modified: 2015-12-21