Implement basic features

.github/workflows/ci.yml

@@ -0,0 +1,138 @@
+name: CI
+on: [push, pull_request]
+jobs:
+  deps:
+    name: Dependencies
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        include:
+          - elixir: 1.11
+            otp: 23
+          - elixir: 1.12
+            otp: 24
+    steps:
+      - name: Cancel Previous Runs
+        uses: styfle/cancel-workflow-action@0.6.0
+        with:
+          access_token: ${{ github.token }}
+
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: Setup
+        uses: erlef/setup-elixir@v1
+        with:
+          elixir-version: ${{ matrix.elixir }}
+          otp-version: ${{ matrix.otp }}
+
+      - name: Retrieve Cached Dependencies
+        uses: actions/cache@v2
+        id: mix-cache
+        with:
+          path: |
+            deps
+            _build
+            priv/plts
+          key: ${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-${{ hashFiles('mix.lock') }}
+
+      - name: Install Dependencies
+        if: steps.mix-cache.outputs.cache-hit != 'true'
+        run: |
+          mkdir -p priv/plts
+          mix local.rebar --force
+          mix local.hex --force
+          mix deps.get
+          mix deps.compile
+          mix dialyzer --plt
+
+  static_code_analysis:
+    name: Static Code Analysis
+    needs: deps
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        include:
+          - elixir: 1.11
+            otp: 23
+          - elixir: 1.12
+            otp: 24
+    steps:
+      - name: Cancel Previous Runs
+        uses: styfle/cancel-workflow-action@0.6.0
+        with:
+          access_token: ${{ github.token }}
+
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: Setup
+        uses: erlef/setup-elixir@v1
+        with:
+          elixir-version: ${{ matrix.elixir }}
+          otp-version: ${{ matrix.otp }}
+
+      - name: Retrieve Cached Dependencies
+        uses: actions/cache@v2
+        id: mix-cache
+        with:
+          path: |
+            deps
+            _build
+            priv/plts
+          key: ${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-${{ hashFiles('mix.lock') }}
+
+      - name: Check Code Format
+        run: mix format --check-formatted
+
+      - name: Run Credo
+        run: mix credo
+
+      - name: Run Dialyzer
+        run: mix dialyzer --no-check --ignore-exit-status
+
+  unit_tests:
+    name: Unit Tests
+    needs: deps
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - elixir: 1.11
+            otp: 23
+          - elixir: 1.12
+            otp: 24
+    steps:
+      - name: Cancel Previous Runs
+        uses: styfle/cancel-workflow-action@0.6.0
+        with:
+          access_token: ${{ github.token }}
+
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: Setup
+        uses: erlef/setup-elixir@v1
+        with:
+          elixir-version: ${{ matrix.elixir }}
+          otp-version: ${{ matrix.otp }}
+
+      - name: Retrieve Cached Dependencies
+        uses: actions/cache@v2
+        id: mix-cache
+        with:
+          path: |
+            deps
+            _build
+            priv/plts
+          key: ${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-${{ hashFiles('mix.lock') }}
+
+      - name: Run test
+        run: mix test --trace --slowest 10

.github/workflows/hex.yml

@@ -0,0 +1,23 @@
+name: Hex
+on:
+  push:
+    tags: ['v*']
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - uses: erlef/setup-elixir@v1
+      with:
+        otp-version: '24'
+        elixir-version: '1.12'
+    - uses: actions/cache@v2
+      with:
+        path: deps
+        key: ${{ runner.os }}-mix-${{ hashFiles('**/mix.lock') }}
+        restore-keys: |
+          ${{ runner.os }}-mix-
+    - run: mix deps.get
+    - run: mix hex.publish --yes
+      env:
+        HEX_API_KEY: ${{ secrets.HEX_API_KEY }}

LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2021 Masatoshi Nishiguchi
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -1,20 +1,49 @@
 # SCD4X
 
-**TODO: Add description**
+[![Hex version](https://img.shields.io/hexpm/v/scd4x.svg 'Hex version')](https://hex.pm/packages/scd4x)
+[![API docs](https://img.shields.io/hexpm/v/scd4x.svg?label=docs 'API docs')](https://hexdocs.pm/scd4x)
+[![CI](https://github.com/mnishiguchi/scd4x/actions/workflows/ci.yml/badge.svg)](https://github.com/mnishiguchi/scd4x/actions/workflows/ci.yml)
+[![Hex](https://github.com/mnishiguchi/scd4x/actions/workflows/hex.yml/badge.svg)](https://github.com/mnishiguchi/scd4x/actions/workflows/hex.yml)
 
-## Installation
+Use [Sensirion SCD4X](https://www.sensirion.com/en/environmental-sensors/carbon-dioxide-sensors/carbon-dioxide-sensor-scd4x) [CO2](https://en.wikipedia.org/wiki/Carbon_dioxide) sensor in Elixir.
 
-If [available in Hex](https://hex.pm/docs/publish), the package can be installed
-by adding `scd4x` to your list of dependencies in `mix.exs`:
+## Usage
+
+### Start the sensor server
+
+```elixir
+iex> {:ok, scd} = SCD4X.start_link(bus_name: "i2c-1")
+{:ok, #PID<0.1407.0>}
+```
+
+### Single shot measurement
 
 ```elixir
-def deps do
-  [
-    {:scd4x, "~> 0.1.0"}
-  ]
-end
+iex> SCD4X.measure_single_shot(scd)
+{:ok,
+ %SCD4X.Measurement{
+   co2_ppm: 638,
+   humidity_rh: 70.49713134765625,
+   temperature_c: 26.63848876953125,
+   timestamp_ms: 400768
+ }}
 ```
 
-Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)
-and published on [HexDocs](https://hexdocs.pm). Once published, the docs can
-be found at [https://hexdocs.pm/scd4x](https://hexdocs.pm/scd4x).
+### Periodical measurement
+
+```elixir
+iex> SCD4X.start_periodic_measurement(scd)
+:ok
+
+iex> SCD4X.measure(scd)
+{:ok,
+ %SCD4X.Measurement{
+   co2_ppm: 612,
+   humidity_rh: 59.07440185546875,
+   temperature_c: 30.331497192382812,
+   timestamp_ms: 620482
+ }}
+
+SCD4X.stop_periodic_measurement(scd)
+:ok
+```

lib/scd4x.ex

@@ -1,18 +1,97 @@
 defmodule SCD4X do
   @moduledoc """
-  Documentation for `SCD4X`.
+  Use Sensirion SCD4X CO2 sensor in Elixir
   """
 
-  @doc """
-  Hello world.
+  use GenServer
 
-  ## Examples
+  require Logger
 
-      iex> SCD4X.hello()
-      :world
+  @type options() :: [GenServer.option() | {:bus_name, bus_name}]
 
+  @typedoc """
+  Which I2C bus to use (defaults to `"i2c-1"`)
   """
-  def hello do
-    :world
+  @type bus_name :: binary
+
+  @default_bus_name "i2c-1"
+  @bus_address 0x62
+
+  @spec start_link(options()) :: GenServer.on_start()
+  def start_link(init_arg \\ []) do
+    gen_server_opts =
+      Keyword.take(init_arg, [:name, :debug, :timeout, :spawn_opt, :hibernate_after])
+
+    GenServer.start_link(__MODULE__, init_arg, gen_server_opts)
+  end
+
+  @spec start_periodic_measurement(GenServer.server()) :: :ok | {:error, any}
+  def start_periodic_measurement(server) do
+    GenServer.call(server, :start_periodic_measurement)
+  end
+
+  @spec stop_periodic_measurement(GenServer.server()) :: :ok | {:error, any}
+  def stop_periodic_measurement(server) do
+    GenServer.call(server, :stop_periodic_measurement)
+  end
+
+  @spec measure(GenServer.server()) :: {:ok, SCD4X.Measurement.t()} | {:error, any}
+  def measure(server) do
+    GenServer.call(server, :measure, 10_000)
+  end
+
+  @spec measure_single_shot(GenServer.server()) :: {:ok, SCD4X.Measurement.t()} | {:error, any}
+  def measure_single_shot(server) do
+    GenServer.call(server, :measure_single_shot, 10_000)
+  end
+
+  @impl GenServer
+  def init(init_arg) do
+    bus_name = init_arg[:bus_name] || @default_bus_name
+    bus_address = @bus_address
+
+    Logger.info(
+      "[SCD4X] Starting on bus #{bus_name} at address #{inspect(bus_address, base: :hex)}"
+    )
+
+    with {:ok, transport} <-
+           SCD4X.Transport.I2C.start_link(bus_name: bus_name, bus_address: bus_address),
+         {:ok, serial_number} <- SCD4X.Comm.serial_number(transport) do
+      Logger.info("[SCD4X] Initializing sensor #{serial_number}")
+
+      state = %{
+        serial_number: serial_number,
+        transport: transport
+      }
+
+      {:ok, state}
+    else
+      _error ->
+        {:stop, "Error connecting to the sensor"}
+    end
+  end
+
+  @impl GenServer
+  def handle_call(:start_periodic_measurement, _from, state) do
+    response = SCD4X.Comm.start_periodic_measurement(state.transport)
+    {:reply, response, state}
+  end
+
+  @impl GenServer
+  def handle_call(:stop_periodic_measurement, _from, state) do
+    response = SCD4X.Comm.stop_periodic_measurement(state.transport)
+    {:reply, response, state}
+  end
+
+  @impl GenServer
+  def handle_call(:measure, _from, state) do
+    response = SCD4X.Comm.read_measurement(state.transport)
+    {:reply, response, state}
+  end
+
+  @impl GenServer
+  def handle_call(:measure_single_shot, _from, state) do
+    response = SCD4X.Comm.read_measurement_single_shot(state.transport)
+    {:reply, response, state}
   end
 end