First Dose of Embedded Elixir with Nerves

Greg Mefford (@ferggo)

Cincinnati Elixir Meetup

2016-02-02

Thanks to Gaslight

Why Embedded?

BeagleBone Black

• Open Hardware
• Lots of Great Peripherals (e.g. CAN)
• Industrial Temperature Option

Elixir     Embedded

<3

• Fault-Tolerance
• Fast Garbage Collection
• Concurrency
• Constrained Hardware
• Binary Protocols
• ...

Nerves

See also Garth's upcoming Nerves talk at ElixirDaze in March

Erlinit

fwup

Buildroot

Cell

Erlinit

fwup

Buildroot

Elixir

Native Code

Mix

Minimal Linux

Erlang Release

Make

Linux Source

Nerves Configuration

Cross-Compiled Binaries

Firmware Image

Erlinit

Bake (fwup)

Elixir

Native Code

Minimal Linux

Erlang Release

Bake

Cross-Compiled Binaries

Firmware Image

System

Toolchain

It's a small team, but community interest is growing. Get involved today!

You!

• Better getting-started documentation
• Better integration between Nerves and Bakeware, and between Nerves and Mix
• WiFi support
• Get Cell working with Nerves
• Update relsync to work with Elixir and Nerves (live-reload)
• Support for BakeWare on Windows

Coming Up:

Quick Demo/Walkthrough

Hack the Gibson!!!1

# Just run this script. It'll be fiiiiiiiine... ;)
ruby -e "$(curl -fsSL https://bakeware.herokuapp.com/bake/install)"

Install Bake

Mac OSX:

(www.bakeware.io)

# libconfuse 2.8 is required but not available in apt
curl -L https://github.com/martinh/libconfuse/releases/download/v2.8/confuse-2.8.tar.gz | tar -xz -C /tmp
pushd /tmp/confuse-2.8
./configure && make && sudo make install
popd
rm -rf /tmp/confuse-2.8

# Install libarchive and libsodium (deps for fwup)
sudo apt-get install libarchive-dev libsodium-dev

# Install fwup
git clone https://github.com/fhunleth/fwup.git
cd fwup
./autogen.sh
./configure && make && sudo make install

# Install bake
ruby -e "$(curl -fsSL https://bakeware.herokuapp.com/bake/install)"

Ubuntu 14.04:

mix new gibson

Setup a Project

defmodule Gibson.Mixfile do
  use Mix.Project

  def project do
    [...]
  end

  def application do
    [
      applications: [:nerves, :nerves_io_neopixel],
      mod: {Gibson, []}
    ]
  end

  defp deps do
    [
      {:nerves_io_neopixel, "~> 0.2.0"},
      {:nerves, github: "nerves-project/nerves"}
    ]
  end
end

use Bake.Config

platform :nerves
default_target :rpi

target :rpi,
  recipe: {"nerves/rpi", "~> 0.1"}

Create a Bakefile

Bake It!

bake system get
bake toolchain get
bake firmware

Burn the SD Card

$ sudo fwup -a -i _images/gibson-rpi.fw -t complete
Use 1.89 GiB memory card found at /dev/sdb? [y/N] y
100%

Erlang Distribution

Configure the VM

## Name of the node
-sname gibson

## Cookie for distributed erlang
-setcookie god

## Start the Elixir shell
-noshell
-user Elixir.IEx.CLI
-extra --no-halt

nerves_demo/rel/vm.args

Connect to the Node

$ iex --sname joey --cookie god

iex> pid = Node.spawn_link :"gibson@Nerves", fn ->
...>   receive do
...>     {:install, client} -> CookieMonster.install(client, self)
...>   end
...> end
#PID<9014.59.0>
iex> send pid, {:install, self}
{:ok, #PID<0.73.0>}
iex> flush
{:installed, #PID<9014.59.0>}
:ok