X-Git-Url: https://gerrit.automotivelinux.org/gerrit/gitweb?a=blobdiff_plain;f=README.md;h=8700cdfe6bcdc16999dd9e1b6eed0a690f5c9d6c;hb=efdc0eb905b57a691badc6e87d9785ee83ce311e;hp=3ae3775bbae005da22ad7a742bf6c3b589b0882b;hpb=b4bdf4e1ecdf99d8ecb0f13a99605aa10154169a;p=apps%2Flow-level-can-service.git diff --git a/README.md b/README.md index 3ae3775..8700cdf 100644 --- a/README.md +++ b/README.md @@ -1,26 +1,162 @@ # OpenXC Message Format Specification -There are two valid message types - single valued and evented. +Version: v0.5.0-dev -There may not be a 1:1 relationship between input and output signals - i.e. raw -engine timing CAN signals may be summarized in an "engine performance" metric on -the abstract side of the interface. +This specification is a part of the [OpenXC platform][OpenXC]. -## Single Valued +An OpenXC vehicle interface sends generic vehicle data over one or more output +interfaces (e.g. USB or Bluetooth) as JSON or Protocol Buffers (protobuf). -The expected format of a single valued message is: +## JSON -{% highlight javascript %} -{"name": "steering_wheel_angle", "value": 45} -{% endhighlight %} +The JSON format is the most flexible and easiest to use. The format is fully +specified in the [JSON.mkd](JSON.mkd) file in this repository. +a more flexible option than binary, but is less compact and +therefore takes more bandwidth and processing power. -## Evented +The JSON format is best for most developers, as it is fairly efficient and very +flexible. -The expected format of an event message is: +## Binary (Protocol Buffers) -{% highlight javascript %} -{"name": "button_event", "value": "up", "event": "pressed"} -{% endhighlight %} +The binary format is encoded using [Google Protocol +Buffers](https://code.google.com/p/protobuf/). The format is specified in the +file [openxc.proto](openxc.proto). The descriptions of the messages can be foud +in the JSON specs - the binary format mirrors this. -This format is good for something like a button event, where there are two -discrete pieces of information in the measurement. +The binary messages are published by the VI using the standard length-delimited +method (any protobuf library should support this). + +The binary format is best if you need to maximize the amount of data that can be +sent from the VI, trading off flexibility for efficiency. + +## Trace File Format + +An OpenXC vehicle trace file is a plaintext file that contains JSON objects, +separated by newlines (which may be either `\r\n` or `\n`, depending on the +platform the trace file was recorded). + +The first line may be a metadata object, although this is optional: + +``` +{"metadata": { + "version": "v3.0", + "vehicle_interface_id": "7ABF", + "vehicle": { + "make": "Ford", + "model": "Mustang", + "trim": "V6 Premium", + "year": 2013 + }, + "description": "highway drive to work", + "driver_name": "TJ Giuli", + "vehicle_id": "17N1039247929" +} +``` + +The following lines are OpenXC messages with a `timestamp` field added, e.g.: + + {"timestamp": 1385133351.285525, "name": "steering_wheel_angle", "value": 45} + +The timestamp is in [UNIX time](http://en.wikipedia.org/wiki/Unix_time) +(i.e. seconds since the UNIX epoch, 00:00:00 UTC, 1/1/1970). + +## Official Signals + +These signal names are a part of the OpenXC specification, although some +manufacturers may support custom message names. + +* steering_wheel_angle + * numerical, -600 to +600 degrees + * 10Hz +* torque_at_transmission + * numerical, -500 to 1500 Nm + * 10Hz +* engine_speed + * numerical, 0 to 16382 RPM + * 10Hz +* vehicle_speed + * numerical, 0 to 655 km/h (this will be positive even if going in reverse + as it's not a velocity, although you can use the gear status to figure out + direction) + * 10Hz +* accelerator_pedal_position + * percentage + * 10Hz +* parking_brake_status + * boolean, (true == brake engaged) + * 1Hz, but sent immediately on change +* brake_pedal_status + * boolean (True == pedal pressed) + * 1Hz, but sent immediately on change +* transmission_gear_position + * states: first, second, third, fourth, fifth, sixth, seventh, eighth, + ninth, tenth, reverse, neutral + * 1Hz, but sent immediately on change +* gear_lever_position + * states: neutral, park, reverse, drive, sport, low, first, second, third, + fourth, fifth, sixth, seventh, eighth, ninth, tenth + * 1Hz, but sent immediately on change +* odometer + * Numerical, km + 0 to 16777214.000 km, with about .2m resolution + * 10Hz +* ignition_status + * states: off, accessory, run, start + * 1Hz, but sent immediately on change +* fuel_level + * percentage + * 2Hz +* fuel_consumed_since_restart + * numerical, 0 - 4294967295.0 L (this goes to 0 every time the vehicle + restarts, like a trip meter) + * 10Hz +* door_status + * Value is State: driver, passenger, rear_left, rear_right. + * Event is boolean: true == ajar + * 1Hz, but sent immediately on change +* headlamp_status + * boolean, true is on + * 1Hz, but sent immediately on change +* high_beam_status + * boolean, true is on + * 1Hz, but sent immediately on change +* windshield_wiper_status + * boolean, true is on + * 1Hz, but sent immediately on change +* latitude + * numerical, -89.0 to 89.0 degrees with standard GPS accuracy + * 1Hz +* longitude + * numerical, -179.0 to 179.0 degrees with standard GPS accuracy + * 1Hz + +## Signals from Diagnostic Messages + +This set of signals is often retreived from OBD-II requests. The units can be +found in the [OBD-II standard](http://en.wikipedia.org/wiki/OBD-II_PIDs#Mode_01). + +* engine_load +* engine_coolant_temperature +* barometric_pressure +* commanded_throttle_position +* throttle_position +* fuel_level +* intake_air_temperature +* intake_manifold_pressure +* running_time +* fuel_pressure +* mass_airflow +* accelerator_pedal_position +* ethanol_fuel_percentage +* engine_oil_temperature +* engine_torque + +License +======= + +Copyright (c) 2012-2014 Ford Motor Company + +Licensed under the BSD license. + +[OpenXC]: http://openxcplatform.com