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feat: align fast-GPS beacons with MeshUI firmware (16-byte format + cadence parity)

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Switch the fast-GPS beacon to the firmware's canonical 16-byte wire format
(magic, key6, lat/lon microdegrees, speed km/h) — no on-wire timestamp; the
receiver stamps its own RX time. Drops compatibility with the older 19-byte app
format.

Mirror the firmware's adaptive send cadence in the app-fallback path
(LocationTrackingService): anchor + dwell motion hysteresis, EMA ground speed,
9-min stationary keepalive, fix-quality (accuracy) gate, and a post-RX hold-off
to avoid channel collisions. Parked nodes now beacon the stable anchor instead
of GPS wander.

Add the fast_gps_region config: region-scope picker in settings backed by the
firmware's fast_gps_region / fast_gps_regions custom vars.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Janez T
2026-06-24 13:17:02 +02:00
parent 3283d4ca20
commit 3c08e150ef
7 changed files with 490 additions and 113 deletions
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29
lib/utils/fast_gps_packet.dart
View File

@@ -1,8 +1,23 @@
import 'dart:typed_data';
/// Fast-GPS position beacon, wire-compatible with the MeshUI firmware
/// (`maybeSendFastGpsUpdate` in MyMesh.cpp).
///
/// 16-byte binary payload sent as a `DATA_TYPE_DEV` group datagram on a
/// non-public channel:
///
/// ```
/// [0] magic 0x47 ('G')
/// [1..6] sender public-key prefix (6 bytes)
/// [7..10] latitude in microdegrees (int32, little-endian)
/// [11..14] longitude in microdegrees (int32, little-endian)
/// [15] ground speed in km/h (uint8, clamped 0..255)
/// ```
///
/// The beacon carries no timestamp — receivers stamp their own RX time.
class FastGpsPacket {
static const int magic = 0x47; // 'G'
static const int _payloadLength = 19;
static const int _payloadLength = 16;
// Store coordinates in microdegrees. This preserves sub-meter precision,
// which comfortably satisfies the meter-accuracy requirement.
static const double coordinateScale = 1e6;
@@ -10,13 +25,15 @@ class FastGpsPacket {
final String senderKey6;
final double latitude;
final double longitude;
final int timestampSeconds;
/// Ground speed in km/h (0..255), as carried in the beacon's trailing byte.
final int speedKmh;
const FastGpsPacket({
required this.senderKey6,
required this.latitude,
required this.longitude,
required this.timestampSeconds,
this.speedKmh = 0,
});
static bool isFastGpsBinary(Uint8List payload) =>
@@ -32,7 +49,7 @@ class FastGpsPacket {
final data = ByteData.sublistView(payload);
final latitude = data.getInt32(7, Endian.little) / coordinateScale;
final longitude = data.getInt32(11, Endian.little) / coordinateScale;
final timestampSeconds = data.getUint32(15, Endian.little);
final speedKmh = data.getUint8(15);
if (!_isValidCoordinate(latitude, longitude)) {
return null;
@@ -42,7 +59,7 @@ class FastGpsPacket {
senderKey6: key6,
latitude: latitude,
longitude: longitude,
timestampSeconds: timestampSeconds,
speedKmh: speedKmh,
);
}
@@ -55,7 +72,7 @@ class FastGpsPacket {
}
data.setInt32(7, (latitude * coordinateScale).round(), Endian.little);
data.setInt32(11, (longitude * coordinateScale).round(), Endian.little);
data.setUint32(15, timestampSeconds, Endian.little);
data.setUint8(15, speedKmh.clamp(0, 255));
return out;
}