--- /dev/null
+# 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 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.
+
+## 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
+
+For protocol specification visit:
+https://github.com/msgpack/msgpack/blob/master/spec.md
+
+We are using the following lib:
+https://github.com/camgunz/cmp
+
+MessagePack provides a binary alternative to ProtoBuf. There are pros & cons to each
+so you can decide what works best for your project.
+
+## 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
Code Review / apps / low-level-can-service.git / blobdiff