Most development will be done in “host” environment. This means that rather than making a change on your computer, then pushing it to the device, we can rapidly develop things from the luxury of our own machine. See this Nerves getting started guide for more information about this. But as a side effect, we will need to be able to configure (at least) two different environment/target combos where:

environment is one of:

environment Description
prod - The production environment * No developer features enabled (such as logs, local fw updates etc).
* No remote shell
* No remote firmware updates.
* Must be digitally signed.
dev - The development environment * Logs most things to the console.
* Remote shell
* Remote firmware updates.
test - The test environment * Only exists for running tests on the host target currently.

And target (where the environment will run) is one of:

target Use
host For development
rpi3 For running on a Raspberry Pi 3
rpi For running on a Raspberry Pi Zero


You will need to configure your Farmbot API, Frontend, and MQTT services for the below commands to work. You can however use the default servers. see config/host/auth_secret_template.exs for more information.

Running unit tests

Tests should be ran while developing features. You should have a local Farmbot stack up and running and configured for this to work. config/host/auth_secret_template.exs will have more full instructions.

MIX_ENV=test mix deps.get # Fetch test env specific deps.
mix test

Feature development

If you plan on developing features, you will probably want to develop them with the dev and host combo. These are both the default values, so you can simply do:

mix deps.get # You should only need to do this once.
iex -S mix # This will start an interactive shell.

Development on device

Sometimes features will need to be developed and tested on the device itself. This is accomplished with the dev and rpi3 combo. It is highly recommended that you have an FTDI cable for this such as this one

MIX_TARGET=rpi3 mix deps.get # Get deps for the rpi3 target. You should only need to do this once.
MIX_TARGET=rpi3 mix firmware # Produce a firmware image.
# Make sure you SDCard is plugged in before the following command.
MIX_TARGET=rpi3 mix firmware.burn # Burn the sdcard. You may be asked for a password here.

Local firmware updates

If you’re bot is connected to your local network, you should be able to push updates over the network to your device.

# make some changes to the code...
MIX_TARGET=rpi3 mix firmware # Build a new fw.
MIX_TARGET=rpi3 mix firmware.push <your device ip address> # Push the new fw to the device.

Your device should now reboot into that new code. As long as you don’t cause a factory reset somehow, (bad init code, typo, etc) you should be able continuously push updates to your device.