library for veml6075

veml6075/.formatter.exs

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+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

veml6075/.gitignore

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+# 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
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+veml6075-*.tar
+
+
+# Temporary files for e.g. tests
+/tmp

veml6075/README.md

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+# Veml6075
+
+**TODO: Add description**
+
+## Installation
+
+If [available in Hex](https://hex.pm/docs/publish), the package can be installed
+by adding `veml6075` to your list of dependencies in `mix.exs`:
+
+```elixir
+def deps do
+  [
+    {:veml6075, "~> 0.1.0"}
+  ]
+end
+```
+
+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/veml6075>.
+

veml6075/lib/veml6075.ex

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+defmodule VEML6075 do
+  use GenServer
+
+  require Logger
+
+  alias VEML6075.{Comm, Config}
+
+  def start_link(options \\ %{}) do
+    GenServer.start_link(__MODULE__, options, name: __MODULE__)
+  end
+
+  def get_measurement do
+    GenServer.call(__MODULE__, :get_measurement)
+  end
+
+  @impl true
+  def init(%{address: address, i2c_bus_name: bus_name} = args) do
+    i2c = Comm.open(bus_name)
+
+    config =
+      args
+      |> Map.take([:gain, :int_time, :shutdown, :interrupt])
+      |> Config.new()
+
+    Comm.write_config(config, i2c, address)
+    :timer.send_interval(1_000, :measure)
+
+    state = %{
+      i2c: i2c,
+      address: address,
+      config: config,
+      last_reading: :no_reading
+    }
+
+    {:ok, state}
+  end
+
+  def init(args) do
+    {bus_name, address} = Comm.discover()
+    transport = "bus: #{bus_name}, address: #{address}"
+
+    Logger.info("Starting VEML6075. Please specify an address and a bus.")
+    Logger.info("Starting on " <> transport)
+
+    defaults =
+      args
+      |> Map.put(:address, address)
+      |> Map.put(:i2c_bus_name, bus_name)
+
+    init(defaults)
+  end
+
+  @impl true
+  def handle_info(
+        :measure,
+        %{i2c: i2c, address: address, config: config} = state
+      ) do
+    last_reading_uva = Comm.readuva(i2c, address, config)
+    last_reading_uvb = Comm.readuvb(i2c, address, config)
+
+    updated_with_reading = %{
+      state
+      | last_reading_uva: last_reading_uva,
+        last_reading_uvb: last_reading_uvb
+    }
+
+    {:noreply, updated_with_reading}
+  end
+
+  @impl true
+  def handle_call(:get_measurement, _from, state) do
+    {:reply, state.last_reading, state}
+  end
+end

veml6075/lib/veml6075/comm.ex

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+defmodule VEML6075.Comm do
+  alias Circuits.I2C
+  alias VEML6075.Config
+
+  @light_register_uva <<7>>
+  @light_register_uvb <<9>>
+  @visible_compensation <<a>>
+  @ir_compensation <<b>>
+
+  def discover(possible_addresses \\ [0x10, 0x48]) do
+    I2C.discover_one!(possible_addresses)
+  end
+
+  def open(bus_name) do
+    {:ok, i2c} = I2C.open(bus_name)
+    i2c
+  end
+
+  def write_config(configuration, i2c, sensor) do
+    command = Config.to_integer(configuration)
+    I2C.write(i2c, sensor, <<0, command::little-16>>)
+  end
+
+  def read(i2c, sensor, configuration) do
+    <<uva_raw::little-16>> = I2C.write_read!(i2c, sensor, @uva_register, 2)
+    <<uvb_raw::little-16>> = I2C.write_read!(i2c, sensor, @uvb_register, 2)
+    <<visible_compensation::little-16>> = I2C.write_read!(i2c, sensor, @uvb_register, 2)
+    <<ir_compensation::little-16>> = I2C.write_read!(i2c, sensor, @uvb_register, 2)
+
+    Config.convert(configuration, uva_raw, uvb_raw, visible_compensation, ir_compensation)
+  end
+end

veml6075/lib/veml6075/config.ex

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+defmodule VEML6075.Config do
+  defstruct uv_it: :it_100_ms,
+            dynamic: false,
+            uv_trig: false,
+            uv_av: false,
+            shutdown: false
+
+  def new, do: struct(__MODULE__)
+  def new(opts), do: struct(__MODULE__, opts)
+
+  def to_integer(config) do
+    reserved = 0
+
+    <<integer::16>> = <<
+      reserved::9,
+      uv_it(config.uv_it):3,
+      high_dynamic(config.dynamic):1,
+      uv_trig(config,uv_trig):1,
+      uv_av(config.uv_av):1,
+      shutdown(config.shutdown)::1
+    >>
+
+    integer
+  end
+
+  defp uv_it(:it_50_ms), do: 0b000
+  defp uv_it(:it_100_ms), do: 0b001
+  defp uv_it(:it_200_ms), do: 0b010
+  defp uv_it(:it_400_ms), do: 0b011
+  defp uv_it(:it_800_ms), do: 0b100
+
+  # Low dynamic: false, High dynamic: true
+  defp high_dynamic(true), do: 1
+  defp high_dynamic(_), do: 0
+
+  # No active force mode trigger: false, Trigger one measurement: true
+  # With true, the sensor conducts one measurement every time, the host writes uv_trig = true, returns to 0 automatically
+  defp uv_trig(true), do: 1
+  defp uv_trig(_), do: 0
+
+  # Activive force mode disable (normal): false, active force mode enable: true
+  defp uv_av(true), do: 1
+  defp uv_av(_), do: 0
+
+  defp shutdown(true), do: 1
+  defp shutdown(_), do: 0
+
+  calibration_alpha_vis = 1.0;
+  calibration_beta_vis  = 1.0;
+  calibration_gamma_ir  = 1.0;
+  calibration_delta_ir  = 1.0;
+
+  uva_vis_coef_a = 2.22
+  uva_ir_coef_b  = 1.33
+  uvb_vis_coef_c = 2.95
+  uvb_ir_coef_d = 1.75
+  uva_responsibility = 0.00110
+  uvb_responsibility = 0.00125
+
+  def convert(uva_raw, uvb_raw, visible_comp, ir_comp) do
+    # Calculate the simple UVIA and UVIB. These are used to calculate the UVI signal.
+    uvia = uva_raw - ((uva_vis_coef_a * calibration_alpha_vis * visible_comp) / calibration_gamma_ir)
+                   - ((uva_ir_coef_b  * calibration_alpha_vis * ir_comp) /  calibration_delta_ir)
+    uvib = uvb_raw - ((uvb_vis_coef_c * calibration_beta_vis * visible_comp) / calibration_gamma_ir)
+                   - ((uvb_ir_coef_d  * calibration_beta_vis * ir_comp) /  calibration_delta_ir)
+
+    # Convert raw UVIA and UVIB to values scaled by the sensor responsivity
+    uvia_scaled = uvia * (1.0 / calibration_alpha_vis) * uva_responsibility
+    uvib_scaled = uvib * (1.0 / calibration_beta_vis) * uvb_responsibility
+
+    # Use UVIA and UVIB to calculate the average UVI:
+    uvi = (uvia_scaled + uvib_scaled) / 2.0;
+
+    {uvia, uvib, uvi}
+  end
+end

veml6075/mix.exs

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+defmodule Veml6075.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :veml6075,
+      version: "0.1.0",
+      elixir: "~> 1.13",
+      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
+    [
+      {:circuits_i2c, "~> 1.0.1"}
+    ]
+  end
+end

veml6075/mix.lock

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+%{
+  "circuits_i2c": {:hex, :circuits_i2c, "1.0.1", "3a820dfa04bc5a92d0ec3c572cacb1a665802b2913fbc25784ed5a2020f12626", [:make, :mix], [{:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "e11393b3f462154ebec5d100859bd5d616e958d9f701e4d62af5764ee84f5213"},
+  "elixir_make": {:hex, :elixir_make, "0.6.3", "bc07d53221216838d79e03a8019d0839786703129599e9619f4ab74c8c096eac", [:mix], [], "hexpm", "f5cbd651c5678bcaabdbb7857658ee106b12509cd976c2c2fca99688e1daf716"},
+}

veml6075/test/test_helper.exs

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+ExUnit.start()

veml6075/test/veml6075_test.exs

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+defmodule Veml6075Test do
+  use ExUnit.Case
+  doctest Veml6075
+
+  test "greets the world" do
+    assert Veml6075.hello() == :world
+  end
+end