Fix example path to x_plane_data include directory.

[erlang-x-plane-data.git] / README.md

diff --git a/README.md b/README.md
index 027e94c..91089e6 100644 (file)
--- a/README.md
+++ b/README.md
@@ -3,40 +3,102 @@
 X-Plane UDP data parser
 =======================
 
-Example
--------
+Examples
+--------
+
+### Receive data packet
 
 ```erlang
-main(Port) ->
-    {ok, Socket} = gen_udp:open(Port, [binary, {active, false}]),
-    {ok, {_, _, <<XPlaneDataPacket/binary>>}} = gen_udp:recv(Socket, 0),
-    {ok, {Index, Groups}} = x_plane_data_raw:of_bin(XPlaneDataPacket),
-
-    % Speeds are in group 3
-    {3, Speeds} = lists:keyfind(3, 1, Groups),
-    { VindKias
-    , VindKeas
-    , VtrueKtas
-    , VtrueKtgs
-    , _
-    , VindMph
-    , VtrueMphas
-    , VtrueMphgs
-    } = Speeds,
-
-    % Pitch roll and headings values are in group 17
-    {17, PitchRollHeadings} = lists:keyfind(17, 1, Groups),
-    { PitchDeg
-    , RollDeg
-    , HdingTrue
-    , HdingMag
-    , _
-    , _
-    , _
-    , _
-    } = PitchRollHeadings,
-
-    ...
+{ok, Socket} = gen_udp:open(Port, [binary, {active, false}]),
+{ok, {_, _, <<XPlaneDataPacket/binary>>}} = gen_udp:recv(Socket, 0),
+```
+
+### Parse data packet
+
+```erlang
+{ok, {64=Index, GroupsRaw}=DataRaw} = x_plane_data_raw:of_bin(XPlaneDataPacket),
+```
+
+### Access parsed data
+
+#### Raw
+
+At this stage, only the structure of the packet was parsed. No attempt at
+interpreting the values have been made:
+
+```erlang
+% Speeds are in group 3
+{3, Speeds} = lists:keyfind(3, 1, GroupsRaw),
+{ VindKias
+, VindKeas
+, VtrueKtas
+, VtrueKtgs
+, _
+, VindMph
+, VtrueMphas
+, VtrueMphgs
+} = Speeds,
+
+% Pitch roll and headings values are in group 17
+{17, PitchRollHeadings} = lists:keyfind(17, 1, GroupsRaw),
+{ PitchDeg
+, RollDeg
+, HdingTrue
+, HdingMag
+, _
+, _
+, _
+, _
+} = PitchRollHeadings,
+```
+
+#### Named
+
+Here we identify what each of the numbered groups mean in a given X-Plane
+version. Right now only X-Plane 10 (packet index 64) is supported and I only
+identified 3 groups so far:
+
+| packet index | group index | group name           |
+|--------------|-------------|----------------------|
+| 64           | 3           | `speeds`             |
+| 64           | 17          | `pitch_roll_heading` |
+| 64           | 20          | `lat_lon_alt`        |
+
+Unidentified groups (with index other than what is listed above) will be
+absent from the list of named groups (think of `x_plane_data_named:of_raw/1` as
+a filter), so you'll have to access their raw version, if needed.
+
+##### Identify
+```erlang
+{ok, {x_plane_data_v10, GroupsNamed}} = x_plane_data_named:of_raw(DataRaw),
+```
+
+##### Access
+```erlang
+-include_lib("x_plane_data/include/x_plane_data_group_lat_lon_alt.hrl").
+-include_lib("x_plane_data/include/x_plane_data_group_pitch_roll_heading.hrl").
+-include_lib("x_plane_data/include/x_plane_data_group_speeds.hrl").
+
+...
+
+{speeds, #x_plane_data_group_speeds
+    { vind_kias   = VindKias
+    , vind_keas   = VindKeas
+    , vtrue_ktas  = VtrueKtas
+    , vtrue_ktgs  = VtrueKtgs
+    , vind_mph    = VindMph
+    , vtrue_mphas = VtrueMphas
+    , vtrue_mphgs = VtrueMphgs
+    }
+} = lists:keyfind(speeds, 1, GroupsNamed),
+
+{pitch_roll_heading, #x_plane_data_group_pitch_roll_heading
+    { pitch_deg  = PitchDeg
+    , roll_deg   = RollDeg
+    , hding_true = HdingTrue
+    , hding_mag  = HdingMag
+    }
+} = lists:keyfind(pitch_roll_heading, 1, GroupsNamed),
 ```
 
 Data format references