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kitt

description

Kitt provides DSRC encoding and decoding functions for Erlang and Elixir and converts decoded message maps to Elixir structs for additional specification enforcement and operations.

Incoming messages are UPER-encoded binary payloads in either raw or hexadecimal format. Elixir structs or basic maps producing the necessary fields for a valid message are accepted for encoding.

Kitt is named for the talking "smart car" character KITT from the 1980s American television series "Knight Rider".

background

Messages, data frames, and their component data elements are based on the 2016-03 ASN1 definition of the J2735 DSRC message set standard developed by the Society of Automative Engineers (SAE).

caution

Kitt does NOT currently provide any mechanism directly for encoding or decoding regional extensions to the DSRC standard messages, frames, and elememnts, instead instantiating those message components as the :asn1_OPENTYPE followed by the raw binary of the regional extension element.

up next

Future planned extensions for Kitt include additional serialization/deserialization functionality to convert decoded messages to common interchange formats such as JSON, Protobuf, and Avro, although this functionality has not yet been fully implemented.

example decoding

iex(1)> Kitt.decode("0014251200000A252F24E6D03FEF9CCC88740D5F7FFFFFFFF098D5F0FDFA1FA1007FFF00004B1090")
{:ok,
 %Kitt.Message.BSM{
   coreData: %Kitt.Message.BSM.CoreData{
     accelSet: %{lat: 2001, long: 2001, vert: -127, yaw: 0},
     accuracy: %{orientation: 65535, semiMajor: 255, semiMinor: 255},
     angle: 127,
     brakes: %{
       abs: :unavailable,
       ...                      <========= Additional fields omitted for brevity
     },
     elev: 2750,
     heading: 22000,
     id: <<0, 0, 40, 148>>,
     lat: 402364127,
     long: -833667351,
     msgCnt: 72,
     secMark: 48275,
     size: %{length: 530, width: 150},
     speed: 305,
     transmission: :unavailable
   },
   partII: nil,
   regional: nil
 }}

example encoding

iex(2)> %Kitt.Message.SPAT{
...(2)>   intersections: [
...(2)>     %{
...(2)>       id: %{id: 1005, region: 0},
...(2)>       moy: 322340,
...(2)>       revision: 1,
...(2)>       states: [
...(2)>         %{
...(2)>           signalGroup: 1,
...(2)>           "state-time-speed": [
...(2)>             %{
...(2)>               eventState: :"stop-And-Remain",
...(2)>               timing: %{maxEndTime: 12966, minEndTime: 12636, startTime: 12166}
...(2)>             }
...(2)>           ]
...(2)>         },
...(2)>         %{
...(2)>           signalGroup: 2,
...(2)>           "state-time-speed": [
...(2)>             %{
...(2)>               eventState: :"permissive-Movement-Allowed",
...(2)>               timing: %{maxEndTime: 12536, minEndTime: 12436, startTime: 12166}
...(2)>             }
...(2)>           ]
...(2)>         },
...(2)>         ...                   <=========== Additional signalGroups omitted for brevity
...(2)>       ],
...(2)>       status: [:trafficDependentOperation],
...(2)>       timeStamp: 16592
...(2)>     }
...(2)>   ],
...(2)>   name: nil,
...(2)>   regional: nil,
...(2)>   timeStamp: nil
...(2)> }
"00136F0018800001F68102004EB2440D009001043C17C318AE1953001022E0BE18C250C3E001010F05F0C6178624000A08782F8630303030006045C17C318041804004021E0BE18C2F0C48002810F05F0C63D067B801808782F8630BC312000E043C17C318AE1953008021E0BE18C2F0C480"