NPPWeatherBot

Setup

Update to latest version of Nerves

mix archive.install https://github.com/nerves-project/archives/raw/master/nerves_bootstrap.ez

Make a new project

mix nerves.new npp_weather_bot --module NPPWeatherBot
cd npp_weather_bot

Set the target in your shell

export MIX_TARGET=rpi3

you'll need to do this every time you open a new shell

Wifi

See the nerves_interim_wifi module and the hello_wifi example project.

Note:

On ACU campus wifi you will need to use the "BasicACUwifi" network. Connecting to this network utilizes a captive portal which will require you to register your devices MAC address using your ACU credentials. The easiest way to do this is by:

1. Get your raspberry pi’s MAC address

• Boot into Raspbian or some other flavor of Linux
• Open the terminal (if in the GUI)
• run cat /sys/class/net/wlan0/address

2. Go here (while behind the ACU firewall)
3. Sign-in using ACU credentials
4. Enter a Device Name; Device Type: Other; MAC Address:

If your weather station will be running on a different network be sure to change the config setting for :ssid, :key_mgmt, and :psk

Temperature

We are using the DS18B20 temperature sensor

There are two models that were purchased The longer sensors wires are: red - 3.3v, yellow - GND, and green - Data The shorter sensors wires are: red - 3.3v, black - GND, and yellow - Data

You need a 4.7K Ohm pull-up resistor between V+ and Data. Here’s a nice article explaining pull-up (and pull-down) resistors: link

We will need to enable the OneWire protocol by following the Advanced Config instructions to get a custom version for fwup.conf from the rpi3 system in deps\nerves\_system\_rpi3 This will in turn allow use of a custom config.txt where we can uncomment this line: dtoverlay=w1-gpio-pullup,gpiopin=4

Twitter

We are using the Twitter client library ExTwitter (docs)

The :consumer_key, :consumer_secret, :access_token, and :access_token_secret have been shared in the NPP Outline Document or you can email me for them directly. You can hard-code them in config.exs or preferably export them to your environment.

Feel free to play around with pattern matching in pick_saying/1 and make your own sayings for your station. Also make sure you have your correct station number in config.exs

WeatherServer

WeatherServer is a GenServer that simply calls into the Tweet module, but this allows us to supervise it in our main application so it can be restarted if it ever crashes.

Scheduling

We are using the job scheduler library Quantum (docs)

Each station will be given a schedule. Go to crontab.guru to better understand the cron schedule expressions.