Connecting to the Raspberry Pi

Mon, 01 Jan 0001 00:00:00 +0000

By default, the cloud-init script sets up a static IP of 192.168.11.137, but you could choose to configure this to something different for each payload box.

Our usual way of connecting is by plugging an ethernet cable into the Pi and connecting it to a laptop. You can read about all the networking options here.

SSH agent forwarding

If you need to authenticate to GitHub to download code, the recommended way is using SSH agent forwarding.

Debugging: Real-Time Clocks (RTC)

Mon, 01 Jan 0001 00:00:00 +0000

A real-time clock (RTC) is a small device equipped with a crystal oscillator and a battery that is responsible for keeping track of the current time, even while your computer (or Raspberry Pi) is powered off.

The “Payload Enclosure Divider” includes a PCF8523 RTC and a holder for a CR1220 coin cell battery. The provided user-config file should automatically set this up. As long as you provide internet access to the Pi once, it will automatically synchronize the RTC with a network time server and everything will just work.

Customizing user-data

Mon, 01 Jan 0001 00:00:00 +0000

The default user-data we start from is as shown below. You will likely need to tweak many of these settings. Descriptions and tips for the most important sections are below.

Note that this is one of two key configuration files. You can read about network-config here.

Starting point user-data file

#cloud-config

# This is the user-data configuration file for cloud-init.
# The cloud-init documentation has more details:
#
# https://cloudinit.readthedocs.io/

system_info:
 default_user:
 name: ubuntu # Allow the default user to shutdown or reboot the system without entering a password (used by our automated scripts)
 sudo: "ALL=(ALL) NOPASSWD: /sbin/poweroff, /sbin/reboot, /sbin/shutdown"

# On first boot, set the (default) ubuntu user's password to "cryosphere"
chpasswd:
 expire: false
 users:
 - name: ubuntu
 password: $6$rounds=4096$aQ7tu0.beL3WAL32$fKxKYvZpY7EMCoxAU1heRomA3v8WvgbqBhhz08QwOtQdlP/DJOP2BThqZFoRW8d2a9PaIKK9BC9NHs1qNnkya1
 type: hash

# Enable password authentication with the SSH daemon
ssh_pwauth: true

# Set a default timezone
timezone: Etc/UTC

## Update apt database and upgrade packages on first boot
package_update: true
package_upgrade: true

## Install additional packages on first boot
packages:
- net-tools
- git
- cmake
- g++
- mosh
- exfat-fuse
- i2c-tools
- rpi.gpio-common
- util-linux-extra

## Write arbitrary files to the file-system
write_files:
- path: /home/ubuntu/initial_setup.sh
 content: |
 #!/bin/bash
 exec > >(tee -a "initial_setup_output.log") 2>&1
 # Miniconda Setup
 wget --progress=bar:force:noscroll "https://github.com/conda-forge/miniforge/releases/latest/download/Miniforge3-Linux-aarch64.sh" -O $HOME/miniconda.sh
 bash $HOME/miniconda.sh -b -p $HOME/miniconda
 cd $HOME
 source .profile
 source miniconda/etc/profile.d/conda.sh
 conda init bash
 # Setup logger environment
 git clone git@github.com:thomasteisberg/uav_radar_logger.git
 # Clone uhd_radar repo
 git clone git@github.com:radioglaciology/uhd_radar.git
 cd uhd_radar
 #git checkout thomas/dask # Uncomment if you want to check out a specific branch other than main
 conda env create -n uhd -f environment-rpi.yaml
 conda activate uhd
 python /home/ubuntu/miniconda/envs/uhd/lib/uhd/utils/uhd_images_downloader.py
 systemctl --user enable radar.service
 systemctl --user enable logger.service
 ifconfig
 sudo reboot
 append: true
- path: /home/ubuntu/.profile
 content: |
 PATH=/home/ubuntu/miniconda/bin:$PATH
 source /home/ubuntu/.bashrc
 append: true
- path: /home/ubuntu/.ssh/known_hosts
 content: |
 github.com ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOMqqnkVzrm0SdG6UOoqKLsabgH5C9okWi0dh2l9GKJl
 github.com ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBEmKSENjQEezOmxkZMy7opKgwFB9nkt5YRrYMjNuG5N87uRgg6CLrbo5wAdT/y6v0mKV0U2w0WZ2YB/++Tpockg=
 github.com ssh-rsa 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
- path: /etc/security/limits.conf # Recommended by Ettus https://kb.ettus.com/USRP_Host_Performance_Tuning_Tips_and_Tricks
 content: |
 ubuntu - rtprio 99
 append: true
- path: /etc/systemd/user/radar.service
 content: |
 [Unit]
 Description=Service to run the radar code on startup

 [Service]
 Type=simple
 WorkingDirectory=/home/ubuntu/uhd_radar/
 ExecStart=/home/ubuntu/uhd_radar/manager/radar_service.sh

 Restart=always
 RestartSec=10

 KillSignal=SIGINT

 [Install]
 WantedBy=default.target
- path: /etc/systemd/user/logger.service
 content: |
 [Unit]
 Description=Service to log data from I2C sensors and automatically shutdown below a voltage threshold

 [Service]
 Type=simple
 WorkingDirectory=/home/ubuntu/uav_radar_logger/
 ExecStart=/home/ubuntu/uav_radar_logger/logger_service.sh

 Restart=always
 RestartSec=60

 KillSignal=SIGINT

 [Install]
 WantedBy=default.target

# Run arbitrary commands at rc.local like time
# These commands are run with root permissions
# If you want commands run as a normal user, put them in initial_setup.sh (see above)
# which is run as the "ubuntu" user (see below)
runcmd:
- chown -R ubuntu:ubuntu /home/ubuntu
- chmod +x /home/ubuntu/initial_setup.sh
- wget -O /etc/udev/rules.d/uhd-usrp.rules https://raw.githubusercontent.com/EttusResearch/uhd/master/host/utils/uhd-usrp.rules
- usermod -a -G i2c ubuntu
- usermod -a -G dialout ubuntu
- usermod -a -G tty ubuntu
- apt remove -y modemmanager
- systemctl stop serial-getty@ttyS0.service && systemctl disable serial-getty@ttyS0.service
- i2cdetect -y 1
- echo "dtoverlay=i2c-rtc,pcf8523" >> /boot/firmware/config.txt
- loginctl enable-linger ubuntu
- mkdir /media/ssd
- chown ubuntu /media/ssd
- chgrp ubuntu /media/ssd
- echo "/dev/sda2 /media/ssd exfat defaults,nofail,uid=1000,gid=1000 0 2" | tee -a /etc/fstab

Password-less shutdown

system_info:
 default_user:
 name: ubuntu # Allow the default user to shutdown or reboot the system without entering a password (used by our automated scripts)
 sudo: "ALL=(ALL) NOPASSWD: /sbin/poweroff, /sbin/reboot, /sbin/shutdown"

One of the features supported by the uav_radar_logger utility is to automatically cleanly shutdown the system if the measured battery voltage drops below a threshold. To facilitate this, the default user must be able to shutdown the system without needing additional authentication. This gives permission for the ubuntu user to call sudo shutdown or sudo reboot without entering a password.

Raspberry Pi Setup on Open Radar Code Architecture

Connecting to the Raspberry Pi

SSH agent forwarding

Debugging: Real-Time Clocks (RTC)

Customizing user-data

Starting point user-data file

Password-less shutdown