Add Waveform Chain command

README.md

@@ -69,6 +69,49 @@ Pigpiox.GPIO.set_mode(gpio, :output)
 Pigpiox.Waveform.repeat(wave_id)
 ```
 
+## Waveform chains
+
+You can compose more complex waveform by chaining them.
+For example, pulsing a GPIO on and off every 500 ms for 10 times and then 50 ms for 100 times and this forever. Chain can be nested.
+
+```elixir
+pulses_500 = [
+  %Pigpiox.Waveform.Pulse{gpio_on: gpio, delay: 500_000},
+  %Pigpiox.Waveform.Pulse{gpio_off: gpio, delay: 500_000}
+]
+
+Pigpiox.Waveform.add_generic(pulses_500)
+
+{:ok, wave_500} = Pigpiox.Waveform.create()
+
+pulses_50 = [
+  %Pigpiox.Waveform.Pulse{gpio_on: gpio, delay: 50_000},
+  %Pigpiox.Waveform.Pulse{gpio_off: gpio, delay: 50_000}
+]
+
+Pigpiox.Waveform.add_generic(pulses_50)
+
+{:ok, wave_50} = Pigpiox.Waveform.create()
+
+Pigpiox.GPIO.set_mode(gpio, :output)
+
+Pigpiox.Waveform.chain(%Pigpiox.Waveform.ChainElement{
+  content: [
+    %Pigpiox.Waveform.ChainElement{
+      content: [wave_500],
+      repeat: 10
+    },
+    %Pigpiox.Waveform.ChainElement{
+      content: [wave_50],
+      repeat: 100
+    }
+  ],
+  repeat: :forever
+})
+
+Pigpiox.Waveform.repeat(wave_id)
+```
+
 ## Clock
 
 The `Pigpiox.Clock` module provides functions that allow you to set a clock on reserved pin.

lib/pigpiox/socket.ex

@@ -32,22 +32,23 @@ defmodule Pigpiox.Socket do
   @doc """
   Runs a command via pigpiod.
   """
-  @spec command(type :: atom, param_one :: integer, param_two :: integer, extents :: list(integer)) :: command_result
-  def command(cmd, p1 \\ 0, p2 \\ 0, extents \\ [])
-  def command(cmd, p1, p2, extents) do
+  @spec command(type :: atom, param_one :: integer, param_two :: integer, extents :: list(integer), bits_size :: integer) :: command_result
+  def command(cmd, p1 \\ 0, p2 \\ 0, extents \\ [], bits_size \\ 32)
+  def command(cmd, p1, p2, extents, bits_size) do
     cmd_code = Pigpiox.Command.code(cmd)
-    GenServer.call(__MODULE__, {:do_command, cmd_code, p1, p2, extents})
+    GenServer.call(__MODULE__, {:do_command, cmd_code, p1, p2, extents, bits_size})
   end
 
-  @spec handle_call({:do_command, integer, integer, integer, list(integer)}, sender :: term, state) :: {:reply, command_result, state}
-  def handle_call({:do_command, command, p1, p2, extents}, _, socket) do
+  @spec handle_call({:do_command, integer, integer, integer, list(integer), integer}, sender :: term, state) :: {:reply, command_result, state}
+  def handle_call({:do_command, command, p1, p2, extents, bits_size}, _, socket) do
+    extents_length = length(extents) * round(bits_size / 8)
     base_msg  = <<command :: native-unsigned-integer-size(32),
                   p1 :: native-unsigned-integer-size(32),
                   p2 :: native-unsigned-integer-size(32),
-                  length(extents) * 4 :: native-unsigned-integer-size(32)>>
+                  extents_length :: native-unsigned-integer-size(32)>>
 
     msg = Enum.reduce(extents, base_msg, fn extent, accum ->
-      accum <> << extent :: native-unsigned-integer-size(32) >>
+      accum <> << extent :: native-unsigned-integer-size(bits_size) >>
     end)
     :ok = :gen_tcp.send(socket, msg)
     {

lib/pigpiox/waveform.ex

@@ -21,6 +21,11 @@ defmodule Pigpiox.Waveform do
     defstruct gpio_on: 0, gpio_off: 0, delay: 0
   end
 
+  defmodule ChainElement do
+    @moduledoc false
+    defstruct content: [], repeat: 1
+  end
+
   @typedoc """
   A pulse used in constructing a waveform. Specifies the GPIO that should be turned on, the GPIO that should be turned off,
   and the delay before the next pulse.
@@ -29,6 +34,8 @@ defmodule Pigpiox.Waveform do
   """
   @type pulse :: %Pulse{}
 
+  @type chain_element :: %ChainElement{}
+
   @doc """
   Adds a list of pulses to the current waveform
 
@@ -42,6 +49,29 @@ defmodule Pigpiox.Waveform do
     Pigpiox.Socket.command(:waveform_add_generic, 0, 0, extents)
   end
 
+  @doc """
+  Chain waveform
+
+  Returns ok or an error.
+  """
+  @spec chain(chain_element :: chain_element) :: {:ok, 0} | {:error, atom}
+  def chain(chain_element) do
+    extents = chain_elements_to_list(chain_element)
+    Pigpiox.Socket.command(:waveform_chain, 0, 0, extents, 8)
+  end
+
+  defp chain_elements_to_list(wave_id) when is_integer(wave_id), do: [wave_id]
+
+  defp chain_elements_to_list(%ChainElement{content: content, repeat: repeat}) do
+    content = Enum.flat_map(content, &chain_elements_to_list/1)
+    [255, 0] ++ content ++ chain_element_repeat_to_list(repeat)
+  end
+
+  defp chain_element_repeat_to_list(:forever), do: [255, 3]
+  defp chain_element_repeat_to_list(repeat) do
+    [255, 1] ++ :erlang.binary_to_list(<<repeat::little-unsigned-integer-size(16)>>)
+  end
+
   @doc """
   Creates a waveform based on previous calls to `add_...`
 

mix.lock

@@ -1,3 +1,5 @@
-%{"dialyxir": {:hex, :dialyxir, "0.5.1", "b331b091720fd93e878137add264bac4f644e1ddae07a70bf7062c7862c4b952", [], [], "hexpm"},
-  "earmark": {:hex, :earmark, "1.2.3", "206eb2e2ac1a794aa5256f3982de7a76bf4579ff91cb28d0e17ea2c9491e46a4", [], [], "hexpm"},
-  "ex_doc": {:hex, :ex_doc, "0.16.2", "3b3e210ebcd85a7c76b4e73f85c5640c011d2a0b2f06dcdf5acdb2ae904e5084", [], [{:earmark, "~> 1.1", [hex: :earmark, repo: "hexpm", optional: false]}], "hexpm"}}
+%{
+  "dialyxir": {:hex, :dialyxir, "0.5.1", "b331b091720fd93e878137add264bac4f644e1ddae07a70bf7062c7862c4b952", [:mix], [], "hexpm"},
+  "earmark": {:hex, :earmark, "1.2.3", "206eb2e2ac1a794aa5256f3982de7a76bf4579ff91cb28d0e17ea2c9491e46a4", [:mix], [], "hexpm"},
+  "ex_doc": {:hex, :ex_doc, "0.16.2", "3b3e210ebcd85a7c76b4e73f85c5640c011d2a0b2f06dcdf5acdb2ae904e5084", [:mix], [{:earmark, "~> 1.1", [hex: :earmark, repo: "hexpm", optional: false]}], "hexpm"},
+}