# PilotPi with Ubuntu Server

WARNING

Ubuntu Server on RPi 4B consumes a lot of current and generates a lot of heat. Design for better heat dissipation and high power consumption when using this hardware.

# Developer Quick Start

# OS Image

Both armhf and arm64 arch are supported.

# armhf

# arm64

# Latest OS

Please refer to official cdimage (opens new window) page for any new updates.

# First boot

When setting up RaPi's WiFi for the first time we recommended using a wired Ethernet connection between your home router and RPi, and a monitor and keyboard.

# Before booting

Mount the SD card onto your computer and modify the network settings. Please follow the official instruction here (opens new window).

Now plug the SD card onto your Pi and boot for the first time. Make sure you have shell access to the RPi - either SSH connection over wired Ethernet, or direct accessing with keyboard and monitor.

# WiFi region

First install required package:

sudo apt-get install crda

Edit the file /etc/default/crda to change the correct WiFi region. Reference List (opens new window)

sudo nano /etc/default/crda

Then your Pi will able to join your WiFi network after reboot.

# Hostname and mDNS

Let's set up hostname at first.

sudo nano /etc/hostname

Change the hostname to whatever you like. Then install the package required by mDNS:

sudo apt-get update
sudo apt-get install avahi-daemon

Perform a reboot.

sudo reboot

Regain the accessibility through WiFi connection after the above operation.

ssh ubuntu@pi_hostname.local

# Password-less Auth (Optional)

You may want to setup passwordless auth (opens new window) as well.

# Setting up OS

# config.txt

The corresponding file in Ubuntu is /boot/firmware/usercfg.txt.

sudo nano /boot/firmware/usercfg.txt

Replace the file with:

# enable sc16is752 overlay
dtoverlay=sc16is752-spi1
# enable I2C-1 and set the frequency to 400KHz
dtparam=i2c_arm=on,i2c_arm_baudrate=400000
# enable spidev0.0
dtparam=spi=on
# enable RC input
enable_uart=1
# enable I2C-0
dtparam=i2c_vc=on
# switch Bluetooth to miniuart
dtoverlay=miniuart-bt

# cmdline.txt

On Ubuntu Server 20.04:

sudo nano /boot/firmware/cmdline.txt

On Ubuntu Server 18.04 or earlier, nobtcmd.txt and btcmd.txt should both be modified.

sudo nano /boot/firmware/nobtcmd.txt

Find console=/dev/ttyAMA0,115200 and remove that part to disable the login shell on serial interface.

Append isolcpus=2 after the last word. The whole file will then look like:

net.ifnames=0 dwc_otg.lpm_enable=0 console=tty1 root=LABEL=writable rootfstype=ext4 elevator=deadline rootwait fixrtc isolcpus=2

The above line tells the Linux kernel do not schedule any process on CPU core 2. We will manually run PX4 onto that core later.

Reboot and SSH onto your Pi.

Check UART interface:

ls /dev/tty*

There should be /dev/ttyAMA0, /dev/ttySC0 and /dev/ttySC1.

Check I2C interface:

ls /dev/i2c*

There should be /dev/i2c-0 and /dev/i2c-1

Check SPI interface:

ls /dev/spidev*

There should be /dev/spidev0.0.

# rc.local

In this section we will configure the auto-start script in rc.local. Note that we need to create this file, as it is not present on a fresh Ubuntu OS.

sudo nano /etc/rc.local

Append the content below to the file:

#!/bin/sh
echo "25" > /sys/class/gpio/export
echo "in" > /sys/class/gpio/gpio25/direction
if [ $(cat /sys/class/gpio/gpio25/value) -eq 1 ] ; then
        echo "Launching PX4"
        cd /home/ubuntu/px4 ; nohup taskset -c 2 ./bin/px4 -d -s pilotpi_mc.config 2 &> 1 > /home/ubuntu/px4/px4.log &
fi
echo "25" > /sys/class/gpio/unexport
exit 0

Save and exit. Then set the correct permissions:

sudo chmod +x /etc/rc.local

Note

Don't forget to turn off the switch when it is not needed!

# CSI camera

WARNING

Enable CSI camera will stop anything works on I2C-0.

sudo nano /boot/firmware/usercfg.txt

Append the following line at the end of file:

start_x=1

# Building the code

To get the very latest version onto your computer, enter the following command into a terminal:

git clone https://github.com/PX4/PX4-Autopilot.git --recursive

Note

This is all you need to do just to build the latest code.

# Set RPi upload target

Set the IP (or hostname) of your RPi using:

export AUTOPILOT_HOST=192.168.X.X

export AUTOPILOT_HOST=pi_hostname.local

Additionally, we need to set the username:

export AUTOPILOT_USER=ubuntu

# Build for armhf target

Build the executable file:

cd Firmware
make scumaker_pilotpi_default

Then upload it with:

make scumaker_pilotpi_default upload

# Alternative build method for armhf (using docker)

If you are compiling for the first time with docker, please refer to the offical docs.

Execute the command in firmware folder:

./Tools/docker_run.sh "export AUTOPILOT_HOST=192.168.X.X; export AUTOPILOT_USER=ubuntu; export NO_NINJA_BUILD=1; make scumaker_pilotpi_default upload"

Note

mDNS is not supported within docker. You must specify the correct IP address every time when uploading.

Note

If your IDE doesn't support ninja build, NO_NINJA_BUILD=1 option will help. You can compile without uploading too. Just remove upload target.

It is also possible to just compile the code with command:

./Tools/docker_run.sh "make scumaker_pilotpi_default"

# Build for arm64 target

Note

This step requires aarch64-linux-gnu tool-chain to be installed.

Build the executable file:

cd PX4-Autopilot
make scumaker_pilotpi_arm64

Then upload it with:

make scumaker_pilotpi_arm64 upload

# Alternative build method for arm64 (using docker)

If you are compiling for the first time with docker, please refer to the offical docs.

Execute the command in PX4-Autopilot folder:

./Tools/docker_run.sh "export AUTOPILOT_HOST=192.168.X.X; export AUTOPILOT_USER=ubuntu; export NO_NINJA_BUILD=1; make scumaker_pilotpi_arm64 upload"

Note

mDNS is not supported within docker. You must specify the correct IP address everytime when uploading.

Note

If your IDE doesn't support ninja build, NO_NINJA_BUILD=1 option will help. You can compile without uploading too - just remove the upload target.

It is also possible to just compile the code with command:

./Tools/docker_run.sh "make scumaker_pilotpi_arm64"

# Manually run PX4

Connect over SSH and run it with:

cd px4
sudo taskset -c 2 ./bin/px4 -s pilotpi_mc.config

Now PX4 is started with multi-rotor configuration.

If you encountered the similar problem executing bin/px4 on your Pi as following:

bin/px4: /lib/xxxx/xxxx: version `GLIBC_2.29' not found (required by bin/px4)

Then you should compile with docker instead.

Before proceeding to next step, clear the existing building at first:

rm -rf build/scumaker_pilotpi_*

Then go back to the corresponding chapter above.

# Post-configuration

Please refer to the instructions here

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