# 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"
```
