Currant

Quadcopter flight control software

Hardware

• Raspberry Pi 3 B+, running Raspian Stretch Lite, housed in a Pibow 3 Coupé
• MPU-9250 Accelerometer/Gyroscope/Compass
• HC-SR04 Ultrasonic Sensor
• Turnigy 2200mAh 3S 20C Battery
• OCDAY 3A Power Distribution Board
• LDPower D-250 ESC/Motor set
• A quadcopter-shaped cutout of polycarbonate with standoffs and velcro.
• USB Wireless Adapter for connecting to the Pi over its own wifi network
• 8BitDo SN30 Pro

To do

• MPL3115A2 Altitude/Pressure Sensor

Initial setup

The vehicle

From a fresh install of Raspian Stretch Lite:

Connect it to the local network with a cable (the wireless card will be used to manage it's own network)

• note the IP
• set a root password
• run the following
  • raspi-config
    • Under Localisation Options, set the proper keyboard layout.
    • Under Advanced, expand the filesystem if it didn't automatically do this at first boot.
    • Under Interfacing Options, enable SSH and I2C.
  • sed -i -E "s/^#?(PermitRootLogin)/\1 yes/" /etc/ssh/sshd_config to change 'PermitRootLogin' for a moment. Ansible will later change that yes to prohibit-password.
  • systemctl restart ssh

The development machine

For /etc/hosts:

192.168.1.XXX currant

Create and sync an SSH key (the keys I generated from macOS with OpenSSH didn't play with paramiko nicely, I had to generate the keys on the Pi and move them locally):

ssh-keygen -t ecdsa -f ~/.ssh/currant_ecdsa -b 521 -N ''
ssh-copy-id -i ~/.ssh/currant_ecdsa root@currant

For ~/.ssh/config:

Host currant
    User root
    IdentityFile ~/.ssh/currant_ecdsa

The vehicle again

Assuming git, pipenv, and ansible are installed locally; clone this repo.

The ansible playbooks will configure the rest of the vehicle; cd into ./ansible/ and run them

• ansible-playbook python3.yml installs the python version set in that file (takes like half an hour)
• ansible-playbook setup.yml configures the wireless network, interfaces, house-cleaning, etc

(these are the instructions I used to originally configure the wireless setup)

The USB wireless card can now be used to connect to the vehicle's wireless network. By default, the network is currant, as is the username. Password is currantpw.

Once connected via wifi, change the line in your /etc/hosts/ to:

172.24.1.1 currant

Development

I open three terminal instances with itermocil --here:

• One for git/local work (pictured left)
• One for running ssh currant, and once inside the vehicle, running preflight and then ./fly.py. (top right)
• One for running pipenv shell ./tower.py, which will watch and sync ./currant/* to /opt/currant on the vehicle. (bottom right)

preflight is ./ansible/files/preflight

Use ./fly.py --setup-bt to set up a bluetooth controller.