can_codec #

Protocol-agnostic CAN bus message codec for Dart. Provides bit-level decoder/encoder with NA/OOR sentinel handling, shared by the nmea2000, rvc, and other J1939-family packages.

Features #

• Bit-level field extraction and insertion (little-endian)
• Resolution and offset scaling for physical values
• Signed and unsigned integer fields with two's complement
• Fixed-length ASCII string fields with 0xFF padding
• Lookup fields (enumerated values)
• NA (data not available), OOR (out of range), and reserved sentinel detection
• MessageDefinition / FieldDefinition schema types
• TransportType enum (single, fastPacket, isoTp)
• Backward-compatible PgnDefinition and PgnTransport aliases

Usage #

Decode a CAN payload #

import 'dart:typed_data';
import 'package:can_codec/can_codec.dart';

const windDef = MessageDefinition(
  pgn: 130306,
  name: 'Wind Data',
  transport: 0,
  dataLength: 6,
  fields: [
    FieldDefinition(name: 'sid', bitOffset: 0, bitLength: 8),
    FieldDefinition(
      name: 'windSpeed', bitOffset: 8, bitLength: 16, resolution: 0.01),
    FieldDefinition(
      name: 'windAngle', bitOffset: 24, bitLength: 16, resolution: 0.0001),
  ],
);

void main() {
  final data = Uint8List.fromList([42, 0x26, 0x02, 0xAA, 0x1E, 0x00]);
  final fields = decode(data, windDef)!;
  print('Speed: ${fields['windSpeed']} m/s'); // 5.50
  print('Angle: ${fields['windAngle']} rad'); // 0.7850
}

Encode field values #

final payload = encode({
  'sid': 42,
  'windSpeed': 5.50,
  'windAngle': 0.7850,
}, windDef);
// payload is a 6-byte Uint8List, little-endian.

Sentinel handling #

// Fields set to all-bits-1 are omitted from decode output (NA).
// Fields set to all-bits-1 minus 1 decode as double.nan (OOR).
// Missing fields in encode are filled with 0xFF (NA).

Testing #

dart test

License #

Apache 2.0 -- see LICENSE for details.