X-Git-Url: https://gerrit.automotivelinux.org/gerrit/gitweb?a=blobdiff_plain;f=README.md;h=b0647dae12c385e40696888f586a065bf93c7394;hb=e40ef7b8d0db0198ed6a77a446c7aa350271fa66;hp=30720db54e04d9f044143ea44671027659d03d88;hpb=2e14ec89c5fb2e3c0d4ed4bcde5e7b04443f0413;p=apps%2Flow-level-can-service.git diff --git a/README.md b/README.md index 30720db..b0647da 100644 --- a/README.md +++ b/README.md @@ -1,18 +1,26 @@ # OpenXC Message Format Specification +Version: v0.3 + 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). + +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. + +The Protocol Buffer format is specified in the file `openxc.proto`. Those are +published using the standard length-delimited method (any protobuf library +should support this). -There are two valid message types - single valued and evented. +## 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} @@ -26,6 +34,216 @@ 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. + +## Diagnostic Messages + +### Requests + +A request to add or update a diagnostic request is sent to a vehicle interface +with this command format: + + { "command": "diagnostic_request", + "request": { + "bus": 1, + "id": 1234, + "mode": 1, + "pid": 5, + "payload": "0x1234", + "multiple_responses": false, + "frequency": 1, + "name": "my_pid" + } + } + } + +**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 - 1 through 15 (1 through 9 are the + standardized modes). + +**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 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. + +**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, defaults to 0) The frequency in Hz to send this + request. To send a single non-recurring request, set this to 0 or leave it + 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. + +A diagnostic request's `bus`, `id`, `mode` and `pid` (or lack of a `pid`) +combine to create a unique key to identify a recurring request. This means that +you cannot simultaneosly have recurring requests at 2Hz and 5Hz for the same PID +from the same ID. + +If you send a new `diagnostic_request` command with a `bus + id + mode + pid` +key matching an existing recurring request, it will update it with whatever +other parameters you've provided (e.g. it will change the frequency if you +specify one). + +To cancel a recurring request, send a `diagnostic_request` command with the +matching request information (i.e. the `bus`, `id`, `mode` and `pid`) but a +frequency of 0. + +Non-recurring requests may have the same `bus+id+mode(+pid)` key as a recurring +request, and they will co-exist without issue. As soon as a non-recurring +request is either completed or times out, it is removed from the active list. + +If you're just requesting a PID, you can use this minimal field set for the +`request` object: + + {"bus": 1, "id": 1234, "mode": 1, "pid": 5} + +### 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 + +### 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 @@ -56,11 +274,11 @@ manufacturers may support custom message names. * 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 @@ -96,26 +314,31 @@ manufacturers may support custom message names. * numerical, -179.0 to 179.0 degrees with standard GPS accuracy * 1Hz -## Raw CAN Message format +### Signals from Diagnostics Messages -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: +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). - {"bus": 1, "id": 1234, "value": "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. +* 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.