X-Git-Url: https://gerrit.automotivelinux.org/gerrit/gitweb?a=blobdiff_plain;f=README.md;h=77758b835865fd28d1c877de832125aba5ff7bcb;hb=3fdb20368c293dce5c69911f7024183191f86da2;hp=8837b522aba639b794045bd3f7e562434ff703fd;hpb=d121ae6f20376dc6fa75ef1140d7767f4ae236af;p=apps%2Fagl-service-can-low-level.git diff --git a/README.md b/README.md index 8837b522..77758b83 100644 --- a/README.md +++ b/README.md @@ -1,30 +1,80 @@ # OpenXC Message Format Specification +Version: v0.6.0 + This specification is a part of the [OpenXC platform][OpenXC]. An OpenXC vehicle interface sends generic vehicle data over one or more output -interfaces (e.g. USB or Bluetooth) as JSON objects, separated by newlines. +interfaces (e.g. USB or Bluetooth) as JSON or Protocol Buffers (protobuf). + +## JSON + +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. + +The JSON format is best for most developers, as it is fairly efficient and very +flexible. + +## Binary (Protocol Buffers) + +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. + +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. -There are two valid message types - single valued and evented. +## Message Pack +MessagePack is an efficient binary serialization format. It lets you exchange data +among multiple languages like JSON, but it's faster and smaller. Small integers are +encoded into a single byte, and typical short strings require only one extra byte +in addition to the strings themselves -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. +For protocol specification visit: +https://github.com/msgpack/msgpack/blob/master/spec.md -## Single Valued +We are using the following lib: +https://github.com/camgunz/cmp -The expected format of a single valued message is: +MessagePack provides a binary alternative to ProtoBuf. There are pros & cons to each +so you can decide what works best for your project. - {"name": "steering_wheel_angle", "value": 45} +## Trace File Format -## Evented +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 expected format of an event message is: +The first line may be a metadata object, although this is optional: - {"name": "button_event", "value": "up", "event": "pressed"} +``` +{"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" +} +``` -This format is good for something like a button event, where there are two -discrete pieces of information in the measurement. +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 @@ -32,51 +82,95 @@ These signal names are a part of the OpenXC specification, although some manufacturers may support custom message names. * steering_wheel_angle - * numerical, degrees + * numerical, -600 to +600 degrees + * 10Hz * torque_at_transmission - * numerical, Nm + * numerical, -500 to 1500 Nm + * 10Hz * engine_speed - * numerical, RPM -* vehicle_speed, numerical, Kph + * 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, - reverse, neutral + 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 + 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, liters (goes to 0 every time the - vehicle interfaces power cycles) + * 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 + * numerical, -89.0 to 89.0 degrees with standard GPS accuracy + * 1Hz * longitude - * numerical + * 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) 2012-2013 Ford Motor Company +Copyright (c) 2012-2014 Ford Motor Company Licensed under the BSD license.