Birdhouse

Hardware needed

We are using the following hardware for our birdhouse:

• Raspberry Pi 3
• Raspberry Pi Camera V2
• A simple LED connected to GPIO Pin 18 and GND
• A simple Servo motor connected to GPIO Pin 23, 5V and GND
• A DHT22 Temperature/Humidity sensor connected to GPIO Pin 4, 3.3V and GND

	GND	3.3V	5V	GPIO
DHT22	x	x		4
Servo	x		x	23
LED	x			18

Setup Elixir

To setup your development environment on either Mac, Linux or Windows head over to the official nerves documentation.

Installation

Setup node.js

We do also need node.js for our UI.

asdf-nodejs

Setup Project

1. Prepare your Phoenix project to build JavaScript and CSS assets:

These steps only need to be done once.

cd bird_app_ui
mix deps.get
npm install --prefix assets

2. Build your assets and prepare them for deployment to the firmware:

# Still in ui directory from the prior step.
# These steps need to be repeated when you change JS or CSS files.
npm install --prefix assets --production
npm run deploy --prefix assets
mix phx.digest

3. Change to the firmware app directory

cd ../bird_app_firmware

4. Specify your target and other environment variables as needed:

export MIX_TARGET=rpi3
export MIX_ENV=dev

# For the telegram bot functions
# export TELEGRAM_BOT_TOKEN=bot_token
# export TELEGRAM_CHAT_ID=chat_id
# export TELEGRAM_CHAT_URL=chat_url
#
# If you're using WiFi:
# export NERVES_NETWORK_SSID=your_wifi_name
# export NERVES_NETWORK_PSK=your_wifi_password

5. Set up the config

Configure the hardware pins and the ssh keys you want to use

# bird_app/bird_app_firmware/config/target.exs

# ...
config :bird_app_hardware,
  led_pin: 18,
  dht_pin: 4,
  servo_pin: 23
# ...

# ...
keys =
  [
    Path.join([System.user_home!(), ".ssh", "id_rsa.pub"]),
    Path.join([System.user_home!(), ".ssh", "id_ecdsa.pub"]),
    Path.join([System.user_home!(), ".ssh", "id_ed25519.pub"])
  ]
# ...

6. Get dependencies, build firmware, and burn it to a SD card:

mix deps.get
mix firmware
mix firmware.burn

7. Insert the SD card into your target board and connect the USB cable or otherwise power it on

8. Wait for it to finish booting (5-10 seconds)

9. Open a browser window on your host computer to http://nerves.local/ or ssh to the raspberry with ssh nerves.local

10. Now whenever you update the code you can also deploy the update via ssh

#create new firmware
cd bird_app_firmware
mix deps.get
mix firmware
mix upload

Ready for production?

If you are ready to deploy to a production environment set your MIX_ENV environment variable to prod

export MIX_ENV=prod

And configure the domain and SSL configuration accordingly like in the following example:

# bird_app/bird_app_firmware/config/target.exs

# ...
config :bird_app_ui, BirdAppUiWeb.Endpoint,
  # Nerves root filesystem is read-only, so disable the code reloader
  code_reloader: false,
  http: [port: 80, protocol_options: [idle_timeout: :infinity]],
  # Use compile-time Mix config instead of runtime environment variables
  load_from_system_env: false,
  # Start the server since we're running in a release instead of through `mix`
  server: true,
  url: [host: "birdhouse.cam", port: 443]
# ...

# bird_app/bird_app_ui/config/prod.exs

# ...
config :bird_app_ui, BirdAppUiWeb.Endpoint,
  cache_static_manifest: "priv/static/cache_manifest.json",
  check_origin: ["//*.birdhouse.cam"],
  live_reload: [
    patterns: [
      ~r"priv/static/.*(js|css|png|jpeg|jpg|gif|svg)$",
      ~r"priv/gettext/.*(po)$",
      ~r"lib/bird_app_ui_web/(live|views)/.*(ex)$",
      ~r"lib/bird_app_ui_web/templates/.*(eex)$"
    ]
  ],
  https: [
    port: 443,
    cipher_suite: :strong,
    otp_app: :bird_app_ui,
    keyfile: "priv/crt.key",
    certfile: "priv/crt.crt",
    cacertfile: "priv/crt.ca-bundle",
    transport_options: [socket_opts: [:inet6]]
  ]

config :bird_app_ui, BirdAppUiWeb.Endpoint,
  force_ssl: [hsts: true]
# ...