X-Git-Url: https://git.xandkar.net/?p=erlang-x-plane-data.git;a=blobdiff_plain;f=README.md;h=382c4b58d3bc85fc417e95b2213a4483770ebb31;hp=2de6895be7b3fee96d464b31c29d67016305e928;hb=HEAD;hpb=25c95554d442f93258a20e5d3e27c2733a20fd6d

diff --git a/README.md b/README.md
index 2de6895..382c4b5 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,10 @@
-[![Build Status](https://travis-ci.org/ibnfirnas/erlang-x_plane_data.svg?branch=master)](https://travis-ci.org/ibnfirnas/erlang-x_plane_data)
+[![Build Status](https://travis-ci.org/xandkar/erlang-x-plane-data.svg?branch=master)](https://travis-ci.org/xandkar/erlang-x-plane-data)
 
 X-Plane UDP data parser
 =======================
 
+![Data output in the cockpit](screenshot.png)
+
 Examples
 --------
 
@@ -16,14 +18,19 @@ Examples
 ### Parse data packet
 
 ```erlang
-{ok, {Index, Groups}} = x_plane_data_raw:of_bin(XPlaneDataPacket),
+{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 attempts at
+interpreting the values have been made:
+
 ```erlang
 % Speeds are in group 3
-{3, Speeds} = lists:keyfind(3, 1, Groups),
+{3, Speeds} = lists:keyfind(3, 1, GroupsRaw),
 { VindKias
 , VindKeas
 , VtrueKtas
@@ -35,7 +42,7 @@ Examples
 } = Speeds,
 
 % Pitch roll and headings values are in group 17
-{17, PitchRollHeadings} = lists:keyfind(17, 1, Groups),
+{17, PitchRollHeadings} = lists:keyfind(17, 1, GroupsRaw),
 { PitchDeg
 , RollDeg
 , HdingTrue
@@ -47,8 +54,106 @@ Examples
 } = PitchRollHeadings,
 ```
 
-Data format references
-----------------------
+#### 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_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),
+
+...
+
+-include_lib("x_plane_data/include/x_plane_data_group_pitch_roll_heading.hrl").
+{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),
+
+...
+
+-include_lib("x_plane_data/include/x_plane_data_group_lat_lon_alt.hrl").
+{lat_lon_alt, #x_plane_data_group_lat_lon_alt
+    { lat_deg   = LatDeg
+    , lon_deg   = LonDeg
+    , alt_ftmsl = AltFtmsl
+    , alt_ftagl = AltFtagl
+    , on_runwy  = OnRunwy
+    , alt_ind   = AltInd
+    , lat_south = LatSouth
+    , lon_west  = LonWest
+    }
+} = lists:keyfind(lat_lon_alt, 1, GroupsNamed),
+```
+
+Packet structure
+----------------
+
+```erlang
+<<"DATA", PacketIndex:8/integer, Groups/binary>>,
+<< GroupIndex:32/little-integer
+ , GroupValue1:32/little-float
+ , GroupValue2:32/little-float
+ , GroupValue3:32/little-float
+ , GroupValue4:32/little-float
+ , GroupValue5:32/little-float
+ , GroupValue6:32/little-float
+ , GroupValue7:32/little-float
+ , GroupValue8:32/little-float
+ , GroupsRest/binary
+>> = Groups,
+```
+
+Where `PacketIndex` indicates something like a schema version, i.e. what each
+of the numbered groups means. For example, in X-Plane 10, packet index is 64
+(character `"@"`) and group 3 contains speed data, in which the 8 group values
+are:
+
+| Location | Label         | Description |
+|----------|---------------|-------------|
+|    1     | `vind_kias`   | Velocity indicated, in knots indicated airspeed. |
+|    2     | `vind_keas`   | Velocity indicated, in knots equivalent airspeed (the calibrated airspeed corrected for adiabatic compressible flow at the craft's current altitude). |
+|    3     | `vtrue_ktas`  | Velocity true (the speed of the craft relative to undisturbed air), in knots true airspeed. |
+|    4     | `vtrue_ktgs`  | Velocity true, in knots true ground speed. |
+|    5     |               | Unused. Contains a dummy value. |
+|    6     | `vind_mph`    | Velocity indicated, in miles per hour. |
+|    7     | `vtrue_mphas` | Velocity true, in miles per hour airspeed. |
+|    8     | `vtrue_mphgs` | Velocity true, in miles per hour ground speed. |
+
+
+References
+----------
 
+- `X-Plane_10_manual.pdf` (distributed with X-Plane 10)
 - http://b58.svglobe.com/data.html
 - http://www.nuclearprojects.com/xplane/xplaneref.html