Auto API L12

The Auto API specification is an open source vehicle data model built for the purpose of providing a consistent data protocol for communication between cars and external 3rd party services. The full introduction to the protocol and the source code can be found on GitHub.

message types

The message types are unified into 3 types.

  • Get commands use 0x00
  • Set commands use 0x01
  • Availability commands use 0x02

Get commands allow a state to be queried (requested) from a connected device.

Set commands allow setting of values, but also are used to transfer the state to the other device.
It should be thought of as one device setting the data in the other one. What the receiving device then does with this data is up to the client / vehicle to decide.

Availability commands allow retrieval of availability information for properties: rate limit and update rate.
The response is sent over 0x01 just like “regular” data, but with the properties availability component populated.

The .yml spec files define the following values and syntax for each capability.


If not defined in a capability – there are no getters for that capability.
If defined, is a dictionary (hash) and requires 2 getters to be automatically synthesized following the pattern:

get_[]_state()                  --> [id.msb, id.lsb, 0x00]
get_[]_properties(property_IDs) --> [id.msb, id.lsb, 0x00] + property_IDs

The _state getter takes no input and requests all state properties in the capability.
The _properties getter takes in property IDs as arguments and requests only those specified properties.

There are additional optional keys available for getters:

  • name: string used to override the full name of the getters (_properties still gets appended)
  • skip_properties_getter: bool used to skip the _properties getter generation
    • If false (default), the _properties getter is only generated when there are more than 1 property in the capability’s state


getters: {}

    name: get_vehicle_location
    skip_properties_getter: true
    name: get_parking_ticket

Binary format:

> gets (requests) ALL the state-properties in a capability
[cap.msb, cap.lsb, 0x00]

> gets (requests) SPECIFIC state-properties in a capability
[cap.msb, cap.lsb, 0x00] + property_IDs

> examples
[0x00, 0x23, 0x00]                > get all Charging state-properties
[0x00, 0x23, 0x00] + [0x03, 0x0c] > get battery_level and charge_mode in Charging


If not defined in a capability – there are no setters for that capability.
Otherwise, it’s an array of dictionaries (hashes) as elements, with the dictionary having the following keys.

The keys are divided into 2 categories: required and optional ones.

Required keys:

  • name: string as the name of the setter
  • description: string description of what the setter does

Optional keys (at least 1 has to be included; can be combined):

  • mandatory: [property_IDs] defines what properties are required as input (and what are actually sent in the setter)
  • optional: [property_IDs] list of optional properties allowed as input. If only optional is defined (no mandatory or constants) - at least 1 input is required
  • constants is an array of constant values defined by the following keys:
    • property_id: property_ID defines the constant property
    • value: [bytes] lists the constant value of the property


  - name: start_stop_ionising
    mandatory: [0x08]
  - name: set_temperature_settings
    optional: [0x03, 0x04, 0x0c]
  - name: control_command
    optional: [0x02, 0x03]
  - name: start_control
      - property_id: 0x01
        value: [0x02]
  - name: stop_control
      - property_id: 0x01
        value: [0x05]

Binary format:

> set properties in a capability
[cap.msb, cap.lsb, 0x01] + properties_bytes

> examples
[0x00, 0x23, 0x01] + [0x0c, 0x00, 0x04, 0x01, 0x00, 0x01, 0x00] > set_charge_mode in Charging


If a capability defines getters, it also enables the usage of availability getters (exept for Fundamental capabilities, i.e. Vehicle Information).
Availability getters are generated using the same “logic” as regular getters, including the properties-specific getter.


// Generate both getters (for ALL properties and specific ones)
getters: {}

// Generate only ALL-propertie getter with a name "getVehicleLocationAvailability"
    name: get_vehicle_location
    skip_properties_getter: true

// Generate both getters named "getParkingTicketAvailability" and "getParkingTicketPropertiesAvailability"
    name: get_parking_ticket

Binary format:

> gets (requests) ALL the state-properties' availability in a capability
[cap.msb, cap.lsb, 0x02]

> gets (requests) SPECIFIC state-properties' availability in a capability
[cap.msb, cap.lsb, 0x02] + property_IDs

> examples
[0x00, 0x23, 0x02]                > get all Charging state-properties' availability
[0x00, 0x23, 0x02] + [0x03, 0x0c] > get battery_level's and charge_mode's availability in Charging


If not defined in a capability – there is no state for that capability.
Defines what properties are exposed to the developer (client). This message is sent over the set message type.

> receive properties (same binary as setters)
[id.msb, id.lsb, 0x01] + state_properties

> examples
[0x00, 0x23, 0x01] + [0x0c, 0x00, 0x04, 0x01, 0x00, 0x01, 0x00] > received charge_mode in Charging

Defines an array of property IDs (or keys).

  • all noting that all properties in a state are exposed / included
  • [property_IDs] defines what properties are exposed


state: all
state: [0x01, 0x02]


Required for every capability.
Properties are used to transmit pieces of information.

Each property can be a base type, a unit type or a custom type.
Base types are defined in the types section below.
Unit types are referenced from unit_types.yml in capability and custom_types files with the syntax: type: unit.[name_of_measurement].
Custom types are referenced from custom_types.yml in capability files with the syntax: type: types.[name_of_custom_type].

Keys available for all properties:

  • id: integer property identifier in hex
  • name: string name of the property in snake_case
  • name_cased: string name of the property in camelCase
  • name_pretty: string human-readable name in a capitalised and whitespaced way, i.e. Charging Power kW
  • type: string type of the property

Other conditional keys:

  • size: integer size of the property’s data component
    • only present for simple properties (base-type) and
    • only present when the size is known in advance, i.e. not for a string or bytes
  • multiple: bool if the property can occure multiple times in a command-state
    • defaults to false.
    • If multiple is present, there is also the name_singular value that represents the name’s singular form
  • description: string an explanation of the property (what it does, means or represents)
  • enum_values: [] a property can also be an enum – enums are explained in the types section

All single-string & uinteger-bytes properties derive their bytes count from the size of the property’s data component size.


  - id: 0x03
    name: model_name
    name_cased: modelName
    name_pretty: Model name
    type: string
    description: The car model name bytes formatted in UTF-8
  - id: 0x0b
    name: charge_port_state
    name_cased: chargePortState
    name_pretty: Charge port state
    type: types.position
  - id: 0x1a
    name: charger_voltage
    name_cased: chargerVoltage
    name_pretty: Charger voltage
    type: unit.electric_potential_difference
    size: 10
    description: Charger voltage
  - id: 0x11
    name: departure_times
    name_cased: departureTimes
    name_pretty: Departure times
    type: types.departure_time
    multiple: true
    name_singular: departure_time

Binary format:

> each property has 1-to-many property components
[, prop.size.msb, prop.size.lsb,, prop.component.size.msb, prop.component.size.lsb, prop.component.value_bytes, 
  ...additional components]

> currently available PROPERTY COMPONENTS are
    0x01 - data component
    0x02 - timestamp component
    0x03 - failure component
    0x05 - availability component

> example
    0x0c        - property ID (Charging's charge_mode)
    0x00, 0x04  - property size
    0x01        - data component ID
    0x00, 0x01  - data component size
    0x00        - value (.immediate)


Types follow the same pattern as properties - they all have the same 4 keys as every property (except the id).

Base types are simple types like integer, uinteger, enum, float, double, string, bytes and timestamp.

Types string and bytes can be considered dynamic by (usually) appearing without size: x.

The timestamp type can be considered like an alias to uinteger of size 8.
Its purpose is to allow developers to use the built-in DateTime data type where it exists.

Among these simple types, the enum is different to others.
All enum types are actually a 1-byte size uinteger values that can be used inside single-type properties too.

Additional keys for enum types:

  • enum_values: [] every enum type has an array of cases with the following keys:
    • id: integer case value in hex
    • name: string case name in snake_case
    • can additionally have the following keys:
      • name_pretty: string case name capitalised and with whitespaces, i.e. Plug-in Hybrid EV
      • verb: string case name when used in an action (not that imporant), i.e. to lock a vehicle or deactivate smth
      • disabled_in_setter: bool defines what values are disallowed to use in a setter (the lib should check the input when combining the bytes for a command)


  - name: active_state
    name_cased: activeState
    name_pretty: Active state
    type: enum
    size: 1
      - id: 0x00
        name: inactive
        verb: deactivate
      - id: 0x01
        name: active
        verb: activate

  - name: network_security
    name_cased: networkSecurity
    name_pretty: Network security
    type: enum
    size: 1
      - id: 0x00
        name: none
      - id: 0x01
        name: wep
        name_pretty: WEP
      - id: 0x02
        name: wpa
        name_pretty: WPA/WPA2 Personal
      - id: 0x03
        name: wpa2_personal
        name_pretty: WPA2 Personal
  - id: 0x17
    name: charging_state
    name_cased: chargingState
    name_pretty: Charging state
    type: enum
    size: 1
      - id: 0x00
        name: not_charging
        verb: stop_charging
      - id: 0x01
        name: charging
        verb: start_charging
      - id: 0x02
        name: charging_complete
        disabled_in_setter: true
      - id: 0x03
        name: initialising
        disabled_in_setter: true
      - id: 0x04
        name: charging_paused
        disabled_in_setter: true
      - id: 0x05
        name: charging_error
        disabled_in_setter: true

Custom types are either commonly used types or ones with multiple pieces of information ordered in a specific byte sequence.
Commonly used types are some enum-s and i.e. timestamp. Custom types are usually defined as type: custom and are singular.

If a custom type contains a sub-type that is itself with a dynanmic size, then the sub-type’s bytes will be prefixed with 2 bytes denoting it’s size (similar to string or bytes).

Additional keys for custom types:

  • items: [] every custom type has an ordered array of items that make up the type
    • consist of base or other custom types in byte order
    • string and bytes has an implied 2 byte size prefix when inside a custom type


  - name: action_item
    name_cased: actionItem
    name_pretty: Action item
    type: custom
      - name: id
        name_cased: id
        name_pretty: ID
        type: uinteger
        size: 1
      - name: name
        name_cased: name
        type: string
        description: Name of the action
  - name: brake_torque_vectoring
    name_cased: brakeTorqueVectoring
    name_pretty: Brake torque vectoring
    type: custom
    size: 2
      - name: axle
        name_cased: axle
        type: types.axle
      - name: state
        name_cased: state
        type: types.active_state
  - name: price_tariff
    name_cased: priceTariff
    name_pretty: Price tariff
    type: custom
      - name: pricing_type
        name_cased: pricingType
        type: enum
        size: 1
          - id: 0x00
            name: starting_fee
          - id: 0x01
            name: per_minute
          - id: 0x02
            name: per_kwh
            name_pretty: Per kWh
      - name: price
        name_cased: price
        type: float
        size: 4
        description: The price in 4-bytes per IEEE 754
      - name: currency
        name_cased: currency
        type: string
        description: The currency alphabetic code per ISO 4217 or crypto currency symbol

Unit types are used with datapoints that express a real-world measurable value.
Each datapoint with a unit defines in the spec what type of measurement it is (i.e. volume, power, length). The data is then transmitted in any of the units corresponding to the measurement type.

The transmitted value is 10 bytes long, with the first 2 expressing the measurement type and the specific unit type, the remaining 8 bytes express the double-value of the unit.


  - id: 0x09
    name: time_to_complete_charge
    name_cased: timeToCompleteCharge
    name_pretty: Time to complete charge
    type: unit.duration
    size: 10
    description: Time until charging completed
  - id: 0x1c
    name: max_range
    name_cased: maxRange
    name_pretty: Max range
    type: unit.length
    size: 10
    description: Maximum electric range with 100% of battery

Binary format:

[measurement_type_id, unit_type_id] + double_value_bytes

duration example:
 0x07,                                              - measurement type is 'duration'
 0x02,                                              - unit type is 'hours'
 0x40, 0x19, 0x99, 0x99, 0x99, 0x99, 0x99, 0x9a     - value is 6.4

length example:
 0x12,                                              - measurement type is 'length'
 0x04,                                              - unit type is 'kilometers'
 0x40, 0x7f, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00     - value is 500.0


Every property has an array of examples (currently 1-2 for a given one).
The examples are under the key examples and can also be used to generate tests.

Examples contain 3 parts:

  • data_component has the hexadecimal value for the data component of the property
  • value(s) contains the parsed value(s) of the hex
  • description describes what the data represents (mostly used in doc-examples)

The values part has 2 mutually exclusive keys: value or values.

value is used when the property has a “simple” type that only has a single value (i.e. an integer, string, enum) or a unit.

  - id: 0x01
    name: lock
    name_cased: lock
    name_pretty: Lock
    type: types.lock_state
      - data_component: '00'
        value: 'unlocked'
        description: Trunk is unlocked

  - id: 0x18
    name: charging_rate
    name_cased: chargingRate
    name_pretty: Charging rate
    type: unit.power
    size: 10
    description: Charge rate when charging
      - data_component: '14024062c00000000000'
          kilowatts: 150.0
        description: Charging rate is 150.0kW

values is used for properties with custom types that contain more than 1 piece of distinct information (i.e. time with it’s hour and minute).
values contains a dictionary with keys as the names of the values in the custom type.

  - id: 0x02
    name: persons_detected
    name_cased: personsDetected
    name_pretty: Persons detected
    type: types.person_detected
    multiple: true
    name_singular: person_detected
      - data_component: '0001'
          location: 'front_left'
          detected: 'detected'
        description: Person detected on the front-left seat

  - id: 0x01
    name: accelerations
    name_cased: accelerations
    name_pretty: Accelerations
    name_singular: acceleration
    type: types.acceleration
    multiple: true
      - data_component: '0001013feba5e353f7ced9'
          direction: 'longitudinal'
            gravity: 0.864
        description: Longitudinal acceleration is 0.864g


capability identifier

Identifiers are defined like this:

    msb: 0x00
    lsb: 0x35

capability version

And API version is defined so:

    intro: 3
    update: 11

requires authorization (permissions)

Every capability has authorization: bool denoting if the capability requires permissions to access.

usable environment

The disabled_in array for when a capability isn’t to be used over some communication mediums:

disabled_in: [ble, web]


Lastly, every command is prefixed with 1 byte for protocol version. This can be found at misc > misc.yml > identification.

Currently for AutoAPI L11 it is:

  version: 0x0b

Binary format:

  uint8     version number


  0x0b,       # Protocol Versions is Level 11
  0x00, 0x23, # Message Identifier for Charging
  0x00        # Command Type for Get Charging State

  0x0b,       # Protocol Versions is Level 11
  0x00, 0x23, # Message Identifier for Open Close Charging Port
  0x01,       # Command Type for Open Close Charging Port
  0x0b,       # Property ID for Charge port state
  0x00, 0x04, # Property Size is 4 bytes
  0x01,       # Data Component identifier
  0x00, 0x01, # Data Component size is 1 byte(s)
  0x01,       # Charge port open