Port Adafruit DHT

This cleans up the C to unify a single driver for all targets.

Also adjusts the port to be request based. Polling will be handled via
Elixir

.gitignore

@@ -7,3 +7,4 @@ erl_crash.dump
 *.ez
 *.beam
 /config/*.secret.exs
+/tmp

Makefile

@@ -0,0 +1,92 @@
+# Makefile for building the DHT* port executable
+#
+# Makefile targets:
+#
+# all/install   build and install
+# clean         clean build products and intermediates
+#
+# Variables to override:
+#
+# MIX_APP_PATH  path to the build directory
+#
+# CC            C compiler. MUST be set if crosscompiling
+# CFLAGS        compiler flags for compiling all C files
+# ERL_CFLAGS	additional compiler flags for files using Erlang header files
+# ERL_EI_INCLUDE_DIR include path to ei.h (Required for crosscompile)
+# ERL_EI_LIBDIR path to libei.a (Required for crosscompile)
+# LDFLAGS       linker flags for linking all binaries
+# ERL_LDFLAGS	additional linker flags for projects referencing Erlang libraries
+
+TOP := $(dir $(realpath $(lastword $(MAKEFILE_LIST))))
+
+PREFIX = $(MIX_COMPILE_PATH)/../priv
+BUILD  = $(MIX_COMPILE_PATH)/../obj
+
+# Set Erlang-specific compile and linker flags
+ERL_CFLAGS ?= -I$(ERL_EI_INCLUDE_DIR)
+ERL_LDFLAGS ?= -L$(ERL_EI_LIBDIR) -lei_st
+
+LDFLAGS +=
+CFLAGS ?= -O2 -Wall -Wextra -Wno-unused-parameter -Werror
+CFLAGS += -std=gnu99 -Impl
+
+DHT_BIN = $(PREFIX)/dht
+
+RPI := rpi rpi0
+RPI2 := rpi2 rpi3 rpi3a rpi4
+BBB := bbb
+
+SRC = src/main.c src/erlcmd.c
+
+ifneq ($(filter $(MIX_TARGET),$(RPI)),)
+TARGET=1
+SRC += src/pi_dht_read.c src/pi_mmio.c src/common_dht_read.c
+else ifneq ($(filter $(MIX_TARGET),$(RPI2)),)
+TARGET=2
+SRC += src/pi_2_dht_read.c src/pi_2_mmio.c src/common_dht_read.c
+else ifneq ($(filter $(MIX_TARGET),$(BBB)),)
+TARGET=3
+SRC += $(wildcard src/bbb*.c) src/common_dht_read.c
+else ifeq ($(MIX_TARGET), host)
+TARGET=0
+CC = gcc
+endif
+
+CC ?= $(CROSSCOMPILER)-gcc
+
+OBJ = $(SRC:src/%.c=$(BUILD)/%.o)
+
+calling_from_make:
+	mix compile
+
+all: $(BUILD) $(PREFIX) $(DHT_BIN)
+
+$(OBJ): Makefile
+
+$(BUILD)/%.o: src/%.c
+	$(CC) -D TARGET=$(TARGET) -c $(ERL_CFLAGS) $(CFLAGS) -o $@ $<
+
+$(PREFIX) $(BUILD):
+	mkdir -p $@
+
+$(DHT_BIN): $(OBJ)
+	$(CC) $^ $(ERL_LDFLAGS) $(LDFLAGS) -o $@
+
+clean:
+	$(RM) $(DHT_BIN) $(OBJ)
+
+format:
+	astyle \
+	    --style=kr \
+	    --indent=spaces=4 \
+	    --align-pointer=name \
+	    --align-reference=name \
+	    --convert-tabs \
+	    --attach-namespaces \
+	    --max-code-length=100 \
+	    --max-instatement-indent=120 \
+	    --pad-header \
+	    --pad-oper \
+	    src/*.c
+
+.PHONY: all clean calling_from_make

lib/application.ex

@@ -0,0 +1,10 @@
+defmodule DHT.Application do
+  use Application
+
+  def start(_type, _args) do
+    opts = [strategy: :one_for_one, name: DHT.Supervisor]
+    children = [DHT.Port]
+
+    Supervisor.start_link(children, opts)
+  end
+end

lib/dht.ex

@@ -1,106 +1,2 @@
 defmodule DHT do
-  use GenServer
-
-  def start_link(pin_num \\ 17, source \\ :circuits_gpio) do
-    GenServer.start_link(__MODULE__, {pin_num, source}, name: __MODULE__)
-  end
-
-  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: []}}
-
-      :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 \\ <<>>)
-
-  def print([{time, _val} = val | rem], acc) do
-    IO.puts("#{inspect(val)}")
-    unless rem == [] do
-      [{next_time, _} | _rem] = rem
-      timing = (next_time - time) |> Kernel.div(1000) |> round()
-      bit = if (timing - 50) in 26..28, do: 0, else: 1
-      IO.puts("\t\t|-- #{timing} us")
-      IO.puts("\t\t|-- #{bit}")
-      print(rem, acc <> <<bit>>)
-    end
-    inspect(acc)
-  end
-
-  def print([], acc), do: inspect(acc)
-
-  def read(server \\ __MODULE__), do: GenServer.call(server, :read)
-
-  def restart(server \\ __MODULE__) do
-    GenServer.stop(server)
-    start_link()
-  end
-
-  def refresh(server \\ __MODULE__) do
-    GenServer.cast(server, :refresh)
-  end
-
-  def handle_call(:read, _from, state) do
-    # Sort them all by timestamp so they are in order
-    # data = Enum.sort_by(state.data, &elem(&1, 0))
-    data = Enum.reverse(state.data)
-
-    {: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)
-
-    # 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)
-
-    Circuits.GPIO.write(pin, 0)
-    # 1 ms trigger
-    :timer.sleep(trigger_time)
-    Circuits.GPIO.write(pin, 1)
-    Circuits.GPIO.set_direction(pin, :input)
-
-    # Circuits.GPIO.set_interrupts(pin, :both)
-    {:noreply, %{state | data: []}}
-  end
-
-  def handle_info({:circuits_gpio, _pin, time, val} = msg, %{data: data} = state) 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

lib/port.ex

@@ -0,0 +1,37 @@
+defmodule DHT.Port do
+  use GenServer
+
+  def start_link(opts) do
+    GenServer.start_link(__MODULE__, opts, name: __MODULE__)
+  end
+
+  def read(pin, sensor) do
+    GenServer.call(__MODULE__, {:read, pin, sensor})
+  end
+
+  @impl true
+  def init(_opts) do
+    exec =
+      Application.app_dir(:dht, "priv")
+      |> Path.join("dht")
+
+    port = Port.open({:spawn_executable, exec}, [{:packet, 2}, :binary, :use_stdio, :exit_status])
+
+    {:ok, %{port: port}}
+  end
+
+  @impl true
+  def handle_call({:read, pin, sensor}, from, state) do
+    message = {:read, from, {pin, sensor}}
+
+    send(state.port, {self(), {:command, :erlang.term_to_binary(message)}})
+    {:noreply, state}
+  end
+
+  @impl true
+  def handle_info({_, {:data, data}}, state) do
+    {condition, result, from} = :erlang.binary_to_term(data)
+    GenServer.reply(from, {condition, result})
+    {:noreply, state}
+  end
+end

mix.exs

@@ -1,28 +1,59 @@
 defmodule Dht.MixProject do
   use Mix.Project
 
+  @source_url "https://github.com/jjcarstens/dht"
+  @version "0.1.0"
+
   def project do
     [
       app: :dht,
-      version: "0.1.0",
+      version: @version,
       elixir: "~> 1.9",
       start_permanent: Mix.env() == :prod,
-      deps: deps()
+      build_embedded: Mix.env() == :prod,
+      compilers: [:elixir_make | Mix.compilers()],
+      make_targets: ["all"],
+      make_clean: ["clean"],
+      deps: deps(),
+      description: description(),
+      docs: docs(),
+      package: package()
     ]
   end
 
-  # Run "mix help compile.app" to learn about applications.
   def application do
     [
+      mod: {DHT.Application, []},
       extra_applications: [:logger]
     ]
   end
 
-  # Run "mix help deps" to learn about dependencies.
   defp deps do
     [
-      {:pigpiox, "~> 0.1"},
-      {:circuits_gpio, "~> 0.4"}
+      {:circuits_gpio, "~> 0.4"},
+      {:elixir_make, "~> 0.6"}
+    ]
+  end
+
+  defp description() do
+    "Drive of DHT 11 and DHT 22 (temperature and humidity sensor)"
+  end
+
+  defp docs do
+    [
+      extras: ["README.md"],
+      main: "readme",
+      source_ref: "v#{@version}",
+      source_url: @source_url
+    ]
+  end
+
+  defp package() do
+    [
+      name: "nerves_dht",
+      files: ["src", "lib", "mix.exs", "README.md", "LICENSE", "Makefile"],
+      licenses: ["GNU 3.0"],
+      links: %{"GitHub" => @source_url}
     ]
   end
 end

mix.lock

@@ -1,5 +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"},
+  "circuits_gpio": {:hex, :circuits_gpio, "0.4.2", "becda6b468271a2dea0c8a500b23b2b5d425501a7d7664c55f96e292af8aef30", [:make, :mix], [{:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "d30787fd140bd09c6bd7fad8f3e7da6a1fa475eb3a6aff5f0c267c6f98cfcd47"},
+  "elixir_make": {:hex, :elixir_make, "0.6.0", "38349f3e29aff4864352084fc736fa7fa0f2995a819a737554f7ebd28b85aaab", [:mix], [], "hexpm", "d522695b93b7f0b4c0fcb2dfe73a6b905b1c301226a5a55cb42e5b14d509e050"},
   "pigpiox": {:hex, :pigpiox, "0.1.2", "efbd55fb4b4507aaf44193cf6bf5fbdff288a351bdfed3f31bdc9377ee5623fd", [:mix], [], "hexpm"},
 }