eefest19demo

Demonstration on Erlang & Elixir Fest 2019

Agenda / Branches

1. Provisioning of hello_nerves project and Building it
2. Burning firm to microSD, Booting and Running IEx
3. Editing lib/hello_nerves.ex and Uploading firmware by ssh nerves.local
4. Burning firm over NervesHub
5. Running device controlling apps integrated with scenic

Instruction

NOTE: Files of Step 1.,2.,3. are only located on respective branches (e.g., "3").

1. Provisioning and Building

Create the project

$ mix nerves.new hello_nerves --init-gadget
$ cd hello_nerves

Setup ssh connection to nerves.local

$ ssh-keygen -t rsa -P "" -C  "eefest19" -f eefest19
Generating public/private rsa key pair.
Your identification has been saved in eefest19.
Your public key has been saved in eefest19.pub.
The key fingerprint is:
SHA256:dz+vWXjW7LqFFgNCybphcHPyi7SkQItkEGMZfMDEhvY eefest19
The key's randomart image is:
+---[RSA 2048]----+
|XB+      ...     |
|oOo.. . +.+      |
|oooo . o *. .    |
|  .Eo   * .. .   |
|     . =S=... o  |
|      . +... . *.|
|              * B|
|             . X |
|              =+o|
+----[SHA256]-----+

$ mv eefest* ~/.ssh/
$ vim ~/.ssh/config
# Add following block
Host nerves.local
  UserKnownHostsFile /dev/null
  StrictHostKeyChecking no
  IdentityFile ~/.ssh/eefest19

$ vim config/config.exs
# Edit as follow
$ git diff config/config.exs
diff --git a/hello_nerves/config/config.exs b/hello_nerves/config/config.exs
index da0c2ac..b5335a6 100644
--- a/hello_nerves/config/config.exs
+++ b/hello_nerves/config/config.exs
@@ -45,7 +45,10 @@ if keys == [],
     """)
 
 config :nerves_firmware_ssh,
-  authorized_keys: Enum.map(keys, &File.read!/1)
+  authorized_keys: [
+    "Paste contents of ~/.ssh/eefest19.pub here"
+  ]
 
 # Configure nerves_init_gadget.
 # See https://hexdocs.pm/nerves_init_gadget/readme.html for more information.

Build the project

$ export MIX_TARGET=rpi0
$ mix deps.get
$ mix firmware

2. Burn the firm to microSD, and Booting and Running IEx

Burn the firmware

Connect microSD to hostPC with SD writer, and then,,,

$ mix firmware.burn

Connect the Nerves by ssh on VirtualEther

$ ssh nerves.local 
Warning: Permanently added 'nerves.local,172.31.125.113' (RSA) to the list of known hosts.
Interactive Elixir (1.8.1) - press Ctrl+C to exit (type h() ENTER for help)
Toolshed imported. Run h(Toolshed) for more info
RingLogger is collecting log messages from Elixir and Linux. To see the
messages, either attach the current IEx session to the logger:

  RingLogger.attach

or print the next messages in the log:

  RingLogger.next

iex([email protected])1> uname 
Nerves nerves-2131 hello_nerves 0.1.0 (bee968a4-58e8-5d2e-6dd1-954970a1529c) arm
iex([email protected])2> HelloNerves.hello
:world

Enjoy the Nerves Hello World and IEx!!

Uploading firmware by local ssh

Edit lib/hello_nerves.ex

$ vim lib/hello_nerves.ex
# Edit as follow
$ git diff lib/hello_nerves.ex 
diff --git a/hello_nerves/lib/hello_nerves.ex b/hello_nerves/lib/hello_nerves.ex
index 0c2bebc..349954c 100644
--- a/hello_nerves/lib/hello_nerves.ex
+++ b/hello_nerves/lib/hello_nerves.ex
@@ -13,6 +13,6 @@ defmodule HelloNerves do
 
   """
   def hello do
-    :world
+    "Erlang & Elixir Fest 2019!"
   end
 end

Recompile the firmware

$ mix firmware

Generate upload.sh

$ mix firmware.gen.script
Writing upload.sh...

Upload firmware by local ssh

$ ./upload.sh 
Path: ./_build/rpi0_dev/nerves/images/hello_nerves.fw
Product: hello_nerves 0.1.0
UUID: 2cd4a00a-042f-5e41-5d8f-cf16de422f3e
Platform: rpi0

Uploading to nerves.local...
Warning: Permanently added '[nerves.local]:8989,[172.31.125.113]:8989' (RSA) to the list of known hosts.
Running fwup...
fwup: Upgrading partition B
|====================================| 100% (31.37 / 31.37) MB
Success!
Elapsed time: 18.933 s
Rebooting...
Received disconnect from 172.31.125.113 port 8989:11: Terminated (shutdown) by supervisor
Disconnected from 172.31.125.113 port 8989

Run IEx and Check the result

$ ssh nerves.local 
Warning: Permanently added 'nerves.local,172.31.125.113' (RSA) to the list of known hosts.
Interactive Elixir (1.8.1) - press Ctrl+C to exit (type h() ENTER for help)
Toolshed imported. Run h(Toolshed) for more info
RingLogger is collecting log messages from Elixir and Linux. To see the
messages, either attach the current IEx session to the logger:

  RingLogger.attach

or print the next messages in the log:

  RingLogger.next

iex([email protected])1> HelloNerves.hello
"Erlang & Elixir Fest 2019!"
iex([email protected])2> exit
Connection to nerves.local closed.

4. Burning firm over NervesHub

Build and Burn firmware

$ cd scenic_dev_ctrl
$ export MIX_TARGET=rpi0
$ mix deps.get
$ mix firmware
$ ./upload.sh

NervesHub and NervesKey setting

TBA (Please consider to attend Nerves Training!!)

5. Running device controlling apps integrated with scenic

Build and Run scenic UI

$ cd scenic_dev_ui
$ mix deps.get
$ mix scenic.run

Build firmware

$ cd scenic_dev_ctrl
$ export MIX_TARGET=rpi0
$ mix deps.get
$ mix firmware
# upload over NervesHub or upload.sh

Then,

Erlang & Elixir Fest 2019 will be appeared on OLED Bonnet. Also, white/black of display can be inverted by pushing #5.

References and Acknowledgement

• https://github.com/nerves-training/nerves_team
  • Special thanks to Nerves Project members and Nerves Friends!!
  • I used branch "8" of its repo as the basis of demonstration of Step 4.