docs: Add BLE and UART protocol specification

docs/c_its-messages.proto

@@ -0,0 +1,122 @@
+syntax = "proto2";
+
+package c_its_io;
+
+// ------------------------------
+// Data Types
+// ------------------------------
+
+message Position {
+  required  float     latitude_deg              =  1;
+  required  float     longitude_deg             =  2;
+}
+
+enum TrafficDir {
+  // for all directions of traffic
+  ALL_DIRECTIONS                                =  0;
+  // for the direction of traffic according to the reference direction, and the portion of traffic upstream of the reference position
+  UPSTREAM                                      =  1;
+  // for the direction of traffic according to the reference direction, and the portion of traffic downstream of the reference position
+  DOWNSTREAM                                    =  2;
+  // for the direction of traffic opposite to the reference direction
+  OPPOSITE                                      =  3;
+}
+
+message VehicleContainer {
+  optional  uint32        heading_deg           =  1; // vehicle heading in degrees, if not "unavailable"
+  optional  uint32        speed                 =  2; // vehicle speed in 1/100 m/s, if not "unavailable"
+  optional  uint32        vehicle_length_dm     =  3; // vehicle length in 1/10 m, if not "unavailable"
+  optional  uint32        vehicle_width_dm      =  4; // vehicle width in 1/10 m, if not "unavailable"
+}
+
+
+// GeoNetworking Destination Area Shape
+enum GNAreaShape {
+  ETSI_AREASHAPE_CIRCLE                         =  0;
+  ETSI_AREASHAPE_RECTANGLE                      =  1;
+  ETSI_AREASHAPE_ELLIPSIS                       =  2;
+  ETSI_AREASHAPE_UNKNOWN                        = 15;
+}
+
+// GeoNetworking Destination Area/ Source Position
+message ITSPosition {
+  optional  int32         latitude              =  1; // Latitude in 1/10th of micro degrees
+  optional  int32         longitude             =  2; // Longitude in 1/10th of micro degrees
+}
+
+// GeoNetworking Destination Area
+message GNArea {
+  optional  GNAreaShape   area                  =  1 [default = ETSI_AREASHAPE_UNKNOWN];
+  optional  ITSPosition   position              =  2;
+  optional  int32         distA                 =  3; // Distance A of the geometric shape in meters
+  optional  int32         distB                 =  4; // Distance B of the geometric shape in meters, mandatory for rectangle and ellipsis
+  optional  int32         angle                 =  5; // Angle of the geometric shape in degrees, mandatory for rectangle and ellipsis
+}
+
+// GeoNetworking Transport
+enum GNTransport {
+  GN_TRANSPORT_DEFAULT                          =  0;
+  GN_TRANSPORT_GUC                              =  2; // GeoUnicast
+  GN_TRANSPORT_GAC                              =  3; // Geographically-Scoped Anycast
+  GN_TRANSPORT_GBC                              =  4; // Geographically-Scoped broadcast
+  GN_TRANSPORT_TSB                              =  5; // Topologically-scoped broadcast
+  GN_TRANSPORT_SHB                              =  7; // Single hop broadcast
+}
+
+message RawMsgTx {
+  required bytes          payload               =  1; // as UPER
+  required uint32         message_type          =  2; // ITS `MessageId` integer value
+
+  required GNTransport    gnTransport           =  3;
+  required GNArea         gnArea                =  4;
+  required uint32         hopLimit              =  5;
+}
+
+// ------------------------------
+// Messages
+// ------------------------------
+
+message PositionState {
+  required  Position      position              =  1;
+  optional  uint32        heading_deg           =  2;
+  optional  uint32        speed                 =  3; // speed in 1/100 m/s
+}
+
+message DenmEvent {
+  required  fixed64       timestamp             =  1; // DENM reference time as UNIX time
+  required  fixed64       validity_end_ts       =  2; // UNIX time when event validity ends (from denm.management.validityDuration)
+  required  fixed32       station_id            =  3; // unique ID of the event when combined with `seq_num`
+  required  uint32        seq_num               =  4; // unique ID of the event when combined with `station_id`
+  optional  Position      event_position        =  5; // event location (from denm.management.eventPosition)
+  optional  uint32        event_heading_deg     =  6; // event heading (from denm.location.eventPositionHeading)
+  optional  TrafficDir    direction             =  7; // relevance traffic direction (from denm.management.trafficDirection)
+  optional  uint32        cause_code            =  8;
+  optional  uint32        sub_cause_code        =  9;
+}
+
+message CamEvent {
+  required  fixed32       station_id            =  1; // Station ID of the vehicle
+  required  uint32        station_type          =  2; // ITS `StationType`
+  required  Position      position              =  3; // vehicle position
+  optional  uint32        vehicle_role          =  4; // ITS `VehicleRole`
+  optional  VehicleContainer  vehicle_data      =  5; // speed, etc unless CAM contains an RSU container
+}
+
+message RawMsgRx {
+  required  uint32        msg_type              =  1; // ITS message type (`MessageId` from PDU header)
+  required  bytes         payload               =  2; // UPER message with Geonetworking and BTP headers
+}
+
+message SerialOutputMsg {
+  oneof                   payload {
+    DenmEvent             denm                  =  1;
+    RawMsgRx              rx_msg                =  2;
+  }
+}
+
+message SerialInputMsg {
+  oneof                   payload {
+    PositionState         position              =  1;
+    RawMsgTx              tx_msg                =  2;
+  }
+}