X-Git-Url: https://gerrit.automotivelinux.org/gerrit/gitweb?a=blobdiff_plain;f=README.md;h=dd5651edace5408612242f00644d833201d65312;hb=75ec5e7c6bf86b6af90168d8e39b3404f4ce6b1e;hp=81574a5cb765a404ce76b156fd99968307588e6a;hpb=9bce073224cd7fb47327743ddc786199887556dc;p=apps%2Fagl-service-can-low-level.git diff --git a/README.md b/README.md index 81574a5c..dd5651ed 100644 --- a/README.md +++ b/README.md @@ -1,23 +1,56 @@ # OpenXC Message Format Specification +Version: v0.4-dev + 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). + +## 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`. Those are published 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. + +## JSON + +This document describes the JSON format and includes a high level description of +each type and field. Each JSON message published by a VI is delimited with a +`\0 ` character. -There are two valid message types - single valued and evented. +The JSON format is best for most developers, as it is fairly efficient and very +flexible. + +### Extra Values + +Any of the following JSON objects may optionally include an `extras` +field. The value may be any valid JSON object or array. The client libraries +will do their best to parse this information into a generic format and pass it +to your application. For example: + + {"name": "steering_wheel_angle", + "value": 45, + "extras": { + "calibrated": false + } + } + +### Single Valued 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. -## Single Valued - The expected format of a single valued message is: {"name": "steering_wheel_angle", "value": 45} -## Evented +### Evented The expected format of an event message is: @@ -26,73 +59,352 @@ The expected format of an event message is: This format is good for something like a button event, where there are two discrete pieces of information in the measurement. +### Raw CAN Message format + +The format for a raw CAN message: + + {"bus": 1, "id": 1234, "data": "0x12345678"} + +**bus** - the numerical identifier of the CAN bus where this message originated, + most likely 1 or 2 (for a vehicle interface with 2 CAN controllers). + +**id** - the CAN message ID + +**data** - up to 8 bytes of data from the CAN message's payload, represented as + a hexidecimal number in a string. Many JSON parser cannot handle 64-bit + integers, which is why we are not using a numerical data type. Each byte in + the string *must* be represented with 2 characters, e.g. `0x1` is `0x01` - the + complete string must have an even number of characters. The `0x` prefix is + optional. + +### Diagnostic Messages + +#### Requests + +A diagnostic request is added or cancelled with a JSON object like this example: + + { "command": "diagnostic_request", + "action": "add", + "request": { + "bus": 1, + "id": 1234, + "mode": 1, + "pid": 5, + "payload": "0x1234", + "multiple_responses": false, + "frequency": 1, + "name": "my_pid" + } + } + } + +* The `command` must be `diagnostic_request.` +* The `action` must be included, and must be one of: + * `add` - create a new one-off or recurring diagnostic request. + * `cancel` - cancel an existing request. +* The details of the request must be included in the `request` field, using + the sub-fields defined below. + +A diagnostic request's `bus`, `id`, `mode` and `pid` (or lack of a `pid`) +combine to create a unique key to identify a request. These four fields will be +referred to as the key of the diagnostic request. For example, to create a +simple one-time diagnostic request: + + { "command": "diagnostic_request", + "action": "add", + "request": { + "bus": 1, + "id": 1234, + "mode": 1, + "pid": 5 + } + } + } + +Requests are completed after any responses are received (unless +`multiple_responses` is set), or the request has timed out after a certain +number of seconds. After a request is completed, you can re-`create` the same +key to make another request. + +Requests with a `frequency` are added as *recurring* requests, e.g. to add the +previous example as a recurring request at 1Hz: + + { "command": "diagnostic_request", + "action": "add", + "request": { + "bus": 1, + "id": 1234, + "mode": 1, + "pid": 5, + "frequency": 1 + } + } + } + +To cancel a recurring request, send a `cancel` action with the same key, e.g.: + + { "command": "diagnostic_request", + "action": "cancel", + "request": { + "bus": 1, + "id": 1234, + "mode": 1, + "pid": 5 + } + } + } + +Simultaneous recurring requests for the same key at different rates (e.g. 1Hz +*and* 2Hz) is not supported. However, non-recurring ("one-off") requests may +exist in parallel with a recurring request for the same key. + +**bus** - the numerical identifier of the CAN bus where this request should be + sent, most likely 1 or 2 (for a vehicle interface with 2 CAN controllers). + +**id** - the CAN arbitration ID for the request. + +**mode** - the OBD-II mode of the request - 0x1 through 0xff (1 through 9 are the + standardized modes and 0x22 is a common proprietary mode). + +**pid** - (optional) the PID for the request, if applicable. + +**payload** - (optional) up to 7 bytes of data for the request's payload + represented as a hexadecimal number in a string. Many JSON parser cannot + handle 64-bit integers, which is why we are not using a numerical data type. + Each byte in the string *must* be represented with 2 characters, e.g. `0x1` + is `0x01` - the complete string must have an even number of characters. The + `0x` prefix is optional. + +**name** - (optional, defaults to nothing) A human readable, string name for + this request. If provided, the response will have a `name` field (much like a + normal translated message) with this value in place of `bus`, `id`, `mode` and + `pid`. + +**multiple_responses** - (optional, false by default) if true, request will stay + active for a full 100ms, even after receiving a diagnostic response message. + This is useful for requests to the functional broadcast arbitration ID + (`0x7df`) when you need to get responses from multiple modules. It's possible + to set this to `true` for non-broadcast requests, but in practice you won't + see any additional responses after the first and it will just take up memory + in the VI for longer. + +**frequency** - (optional) Make this request a recurring request, at a this + frequency in Hz. To send a single non-recurring request, leave this field out. + +**decoded_type** - (optional, defaults to "obd2" if the request is a recognized +OBD-II mode 1 request, otherwise "none") If specified, the valid values are +`"none"` and `"obd2"`. If `obd2`, the payload will be decoded according to the +OBD-II specification and returned in the `value` field. Set this to `none` to +manually override the OBD-II decoding feature for a known PID. + +#### Responses + +The response to a successful request: + + {"bus": 1, + "id": 1234, + "mode": 1, + "pid": 5, + "success": true, + "payload": "0x1234", + "value": 4660} + +and to an unsuccessful request, with the `negative_response_code` and no `pid` +echo: + + {"bus": 1, + "id": 1234, + "mode": 1, + "success": false, + "negative_response_code": 17} + +**bus** - the numerical identifier of the CAN bus where this response was + received. + +**id** - the CAN arbitration ID for this response. + +**mode** - the OBD-II mode of the original diagnostic request. + +**pid** - (optional) the PID for the request, if applicable. + +**success** - true if the response received was a positive response. If this + field is false, the remote node returned an error and the + `negative_response_code` field should be populated. + +**negative_response_code** - (optional) If requested node returned an error, + `success` will be `false` and this field will contain the negative response + code (NRC). + +Finally, the `payload` and `value` fields are mutually exclusive: + +**payload** - (optional) up to 7 bytes of data returned in the response, + represented as a hexadecimal number in a string. Many JSON parser cannot + handle 64-bit integers, which is why we are not using a numerical data type. + +**value** - (optional) if the response had a payload, this may be the + payload interpreted as an integer. + +The response to a simple PID request would look like this: + + {"success": true, "bus": 1, "id": 1234, "mode": 1, "pid": 5, "payload": "0x2"} + +### Commands + +In addition to the `diagnostic_request` command described earlier, there are +other possible values for the `command` field. + +#### Version Query + +The `version` command triggers the VI to inject a firmware version identifier +response into the outgoing data stream. + +**Request** + + { "command": "version"} + +**Response** + + { "command_response": "version", "message": "v6.0-dev (default)"} + +#### Device ID Query + +The `device_id` command triggers the VI to inject a unique device ID (e.g. the +MAC address of an included Bluetooth module) into into the outgoing data stream. + +**Request** + + { "command": "device_id"} + +**Response** + + { "command_response": "device_id", "message": "0012345678"} + +### 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, 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 - -## Raw CAN Message format - -An OpenXC vehicle interface may also output raw CAN messages. Each CAN message -is sent as a JSON object, separated by newlines. The format of each object is: + * numerical, -179.0 to 179.0 degrees with standard GPS accuracy + * 1Hz - {"bus": 1, "id": 1234, "value": "0x12345678"} +### Signals from Diagnostics Messages -**bus** - the numerical identifier of the CAN bus where this message originated, - most likely 1 or 2 (for a vehicle interface with 2 CAN controllers). +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). -**id** - the CAN message ID - -**data** - up to 8 bytes of data from the CAN message's payload, represented as - a hexidecimal number in a string. Many JSON parser cannot handle 64-bit - integers, which is why we are not using a numerical data type. +* 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.