experiment with pigpio

.formatter.exs

@@ -0,0 +1,4 @@
+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

README.md

@@ -18,3 +18,17 @@ To attempt to trigger and read, run:
 DHT.refresh # this triggers sensor to start sending data
 DHT.read # shows the data captured from the last trigger attempt
 ```
+
+This experiment is testing with `circuits_gpio` and `pigpiox`. You can switch between the two:
+```elixir
+# circuits_gpio by default. But you can also specify
+DHT.start_link(17, :circuits_gpio)
+
+# For pigpio
+DHT.start_link(17, :pigpiox)
+```
+
+You can use the included `weather_man` nerves app to quickly build firmware
+```elixir
+$ cd weather_man && mix firmware
+```

dht.ex → lib/dht.ex

@@ -1,15 +1,25 @@
 defmodule DHT do
   use GenServer
 
-  def start_link(pin_num \\ 17) do
-    GenServer.start_link(__MODULE__, pin_num, name: __MODULE__)
+  def start_link(pin_num \\ 17, source \\ :circuits_gpio) do
+    GenServer.start_link(__MODULE__, {pin_num, source}, name: __MODULE__)
   end
 
-  def init(pin_num) do
-    {:ok, pin} = Circuits.GPIO.open(pin_num, :input)
-    Circuits.GPIO.set_interrupts(pin, :both)
+  def init({pin_num, source}) do
+    case source do
+      :circuits_gpio ->
+        {:ok, pin} = Circuits.GPIO.open(pin_num, :input)
+        Circuits.GPIO.set_interrupts(pin, :both)
+        {:ok, %{pin: pin, data: []}}
 
-    {:ok, %{pin: pin, data: []}}
+      :pigpiox ->
+        Pigpiox.GPIO.set_mode(pin_num, :input)
+        {:ok, watch_pid} = Pigpiox.GPIO.watch(pin_num)
+        {:ok, %{pin: pin_num, watch_pid: watch_pid, data: []}}
+
+      unknown ->
+        {:stop, "Don't know how to use source #{inspect(unknown)}"}
+    end
   end
 
   def print(list, acc \\ <<>>)
@@ -48,6 +58,25 @@ defmodule DHT do
     {:reply, %{state | data: data}, state}
   end
 
+  def handle_cast(:refresh, %{pin: pin} = state) when is_number(pin) do
+    Pigpiox.GPIO.set_mode(pin, :output)
+
+    # Datasheet says minimum of 1ms, but can allow up to 10ms
+    # for the trigger. This is here to alter more easily
+    trigger_time = Application.get_env(:dht, :trigger_time, 1)
+
+    Pigpiox.GPIO.write(pin, 0)
+    # 1 ms trigger
+    :timer.sleep(trigger_time)
+    Pigpiox.GPIO.write(pin, 1)
+    Pigpiox.GPIO.set_mode(pin, :input)
+
+    Pigpiox.GPIO.watch(pin)
+
+    # Circuits.GPIO.set_interrupts(pin, :both)
+    {:noreply, %{state | data: []}}
+  end
+
   def handle_cast(:refresh, %{pin: pin} = state) do
     Circuits.GPIO.set_direction(pin, :output)
 
@@ -69,4 +98,9 @@ defmodule DHT do
     IO.inspect(msg)
     {:noreply, %{state | data: [{time, val} | data]}}
   end
+
+  def handle_info({:gpio_leveL_change, _gpio, val} = msg, %{data: data} = state) do
+    IO.inspect(msg)
+    {:noreply, %{state | data: [{System.monotonic_time(:nanosecond), val} | data]}}
+  end
 end

mix.exs

@@ -0,0 +1,28 @@
+defmodule Dht.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :dht,
+      version: "0.1.0",
+      elixir: "~> 1.9",
+      start_permanent: Mix.env() == :prod,
+      deps: deps()
+    ]
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      extra_applications: [:logger]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      {:pigpiox, "~> 0.1"},
+      {:circuits_gpio, "~> 0.4"}
+    ]
+  end
+end

mix.lock

@@ -0,0 +1,5 @@
+%{
+  "circuits_gpio": {:hex, :circuits_gpio, "0.4.2", "becda6b468271a2dea0c8a500b23b2b5d425501a7d7664c55f96e292af8aef30", [:make, :mix], [{:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm"},
+  "elixir_make": {:hex, :elixir_make, "0.6.0", "38349f3e29aff4864352084fc736fa7fa0f2995a819a737554f7ebd28b85aaab", [:mix], [], "hexpm"},
+  "pigpiox": {:hex, :pigpiox, "0.1.2", "efbd55fb4b4507aaf44193cf6bf5fbdff288a351bdfed3f31bdc9377ee5623fd", [:mix], [], "hexpm"},
+}

test/test_helper.exs

@@ -0,0 +1 @@
+ExUnit.start()

weather_man/.formatter.exs

@@ -0,0 +1,4 @@
+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

weather_man/.gitignore

@@ -0,0 +1,17 @@
+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where third-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump

weather_man/README.md

@@ -0,0 +1,32 @@
+# WeatherMan
+
+**TODO: Add description**
+
+## Targets
+
+Nerves applications produce images for hardware targets based on the
+`MIX_TARGET` environment variable. If `MIX_TARGET` is unset, `mix` builds an
+image that runs on the host (e.g., your laptop). This is useful for executing
+logic tests, running utilities, and debugging. Other targets are represented by
+a short name like `rpi3` that maps to a Nerves system image for that platform.
+All of this logic is in the generated `mix.exs` and may be customized. For more
+information about targets see:
+
+https://hexdocs.pm/nerves/targets.html#content
+
+## Getting Started
+
+To start your Nerves app:
+  * `export MIX_TARGET=my_target` or prefix every command with
+    `MIX_TARGET=my_target`. For example, `MIX_TARGET=rpi3`
+  * Install dependencies with `mix deps.get`
+  * Create firmware with `mix firmware`
+  * Burn to an SD card with `mix firmware.burn`
+
+## Learn more
+
+  * Official docs: https://hexdocs.pm/nerves/getting-started.html
+  * Official website: https://nerves-project.org/
+  * Forum: https://elixirforum.com/c/nerves-forum
+  * Discussion Slack elixir-lang #nerves ([Invite](https://elixir-slackin.herokuapp.com/))
+  * Source: https://github.com/nerves-project/nerves

weather_man/config/config.exs

@@ -0,0 +1,31 @@
+# This file is responsible for configuring your application
+# and its dependencies with the aid of the Mix.Config module.
+#
+# This configuration file is loaded before any dependency and
+# is restricted to this project.
+use Mix.Config
+
+config :weather_man, target: Mix.target()
+
+# Customize non-Elixir parts of the firmware. See
+# https://hexdocs.pm/nerves/advanced-configuration.html for details.
+
+config :nerves, :firmware, rootfs_overlay: "rootfs_overlay"
+
+# Use shoehorn to start the main application. See the shoehorn
+# docs for separating out critical OTP applications such as those
+# involved with firmware updates.
+
+config :shoehorn,
+  init: [:nerves_runtime, :nerves_init_gadget],
+  app: Mix.Project.config()[:app]
+
+# Use Ringlogger as the logger backend and remove :console.
+# See https://hexdocs.pm/ring_logger/readme.html for more information on
+# configuring ring_logger.
+
+config :logger, backends: [RingLogger]
+
+if Mix.target() != :host do
+  import_config "target.exs"
+end

weather_man/config/target.exs

@@ -0,0 +1,44 @@
+use Mix.Config
+
+# Authorize the device to receive firmware using your public key.
+# See https://hexdocs.pm/nerves_firmware_ssh/readme.html for more information
+# on configuring nerves_firmware_ssh.
+
+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"])
+  ]
+  |> Enum.filter(&File.exists?/1)
+
+if keys == [],
+  do:
+    Mix.raise("""
+    No SSH public keys found in ~/.ssh. An ssh authorized key is needed to
+    log into the Nerves device and update firmware on it using ssh.
+    See your project's config.exs for this error message.
+    """)
+
+config :nerves_firmware_ssh,
+  authorized_keys: Enum.map(keys, &File.read!/1)
+
+# Configure nerves_init_gadget.
+# See https://hexdocs.pm/nerves_init_gadget/readme.html for more information.
+
+# Setting the node_name will enable Erlang Distribution.
+# Only enable this for prod if you understand the risks.
+node_name = if Mix.env() != :prod, do: "weather_man"
+
+config :nerves_init_gadget,
+  ifname: "usb0",
+  address_method: :dhcpd,
+  mdns_domain: "nerves.local",
+  node_name: node_name,
+  node_host: :mdns_domain
+
+# Import target specific config. This must remain at the bottom
+# of this file so it overrides the configuration defined above.
+# Uncomment to use target specific configurations
+
+# import_config "#{Mix.target()}.exs"

weather_man/lib/weather_man.ex

@@ -0,0 +1,18 @@
+defmodule WeatherMan do
+  @moduledoc """
+  Documentation for WeatherMan.
+  """
+
+  @doc """
+  Hello world.
+
+  ## Examples
+
+      iex> WeatherMan.hello
+      :world
+
+  """
+  def hello do
+    :world
+  end
+end

weather_man/lib/weather_man/application.ex

@@ -0,0 +1,42 @@
+defmodule WeatherMan.Application do
+  # See https://hexdocs.pm/elixir/Application.html
+  # for more information on OTP Applications
+  @moduledoc false
+
+  use Application
+
+  def start(_type, _args) do
+    # See https://hexdocs.pm/elixir/Supervisor.html
+    # for other strategies and supported options
+    opts = [strategy: :one_for_one, name: WeatherMan.Supervisor]
+    children =
+      [
+        # Children for all targets
+        # Starts a worker by calling: WeatherMan.Worker.start_link(arg)
+        # {WeatherMan.Worker, arg},
+      ] ++ children(target())
+
+    Supervisor.start_link(children, opts)
+  end
+
+  # List all child processes to be supervised
+  def children(:host) do
+    [
+      # Children that only run on the host
+      # Starts a worker by calling: WeatherMan.Worker.start_link(arg)
+      # {WeatherMan.Worker, arg},
+    ]
+  end
+
+  def children(_target) do
+    [
+      # Children for all targets except host
+      # Starts a worker by calling: WeatherMan.Worker.start_link(arg)
+      # {WeatherMan.Worker, arg},
+    ]
+  end
+
+  def target() do
+    Application.get_env(:weather_man, :target)
+  end
+end

weather_man/mix.exs

@@ -0,0 +1,73 @@
+defmodule WeatherMan.MixProject do
+  use Mix.Project
+
+  @app :weather_man
+  @version "0.1.0"
+  @all_targets [:rpi, :rpi0, :rpi2, :rpi3, :rpi3a, :rpi4, :bbb, :x86_64]
+
+  def project do
+    [
+      app: @app,
+      version: @version,
+      elixir: "~> 1.9",
+      archives: [nerves_bootstrap: "~> 1.6"],
+      start_permanent: Mix.env() == :prod,
+      build_embedded: true,
+      aliases: [loadconfig: [&bootstrap/1]],
+      deps: deps(),
+      releases: [{@app, release()}],
+      preferred_cli_target: [run: :host, test: :host]
+    ]
+  end
+
+  # Starting nerves_bootstrap adds the required aliases to Mix.Project.config()
+  # Aliases are only added if MIX_TARGET is set.
+  def bootstrap(args) do
+    Application.start(:nerves_bootstrap)
+    Mix.Task.run("loadconfig", args)
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      mod: {WeatherMan.Application, []},
+      extra_applications: [:logger, :runtime_tools]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      # Dependencies for all targets
+      {:nerves, "~> 1.5.0", runtime: false},
+      {:shoehorn, "~> 0.6"},
+      {:ring_logger, "~> 0.6"},
+      {:toolshed, "~> 0.2"},
+      {:dht, path: "../"},
+
+      # Dependencies for all targets except :host
+      {:nerves_runtime, "~> 0.6", targets: @all_targets},
+      {:nerves_init_gadget, "~> 0.4", targets: @all_targets},
+
+      # Dependencies for specific targets
+      {:nerves_system_rpi, "~> 1.8", runtime: false, targets: :rpi},
+      {:nerves_system_rpi0, "~> 1.8", runtime: false, targets: :rpi0},
+      {:nerves_system_rpi2, "~> 1.8", runtime: false, targets: :rpi2},
+      {:nerves_system_rpi3, "~> 1.8", runtime: false, targets: :rpi3},
+      {:nerves_system_rpi3a, "~> 1.8", runtime: false, targets: :rpi3a},
+      {:nerves_system_rpi4, "~> 1.8", runtime: false, targets: :rpi4},
+      {:nerves_system_bbb, "~> 2.3", runtime: false, targets: :bbb},
+      {:nerves_system_x86_64, "~> 1.8", runtime: false, targets: :x86_64},
+    ]
+  end
+
+  def release do
+    [
+      overwrite: true,
+      cookie: "#{@app}_cookie",
+      include_erts: &Nerves.Release.erts/0,
+      steps: [&Nerves.Release.init/1, :assemble],
+      strip_beams: Mix.env() == :prod
+    ]
+  end
+end