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feat: Update Cayenne LPP GPS encoding/decoding to use 3-byte signed big-endian format

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Janez T
2025-10-26 16:57:21 +01:00
parent 3a20b756fd
commit b8147e904c
3 changed files with 166 additions and 105 deletions
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66
lib/services/cayenne_lpp_parser.dart
View File

@@ -148,19 +148,33 @@ class CayenneLppParser {
break;
case MeshCoreConstants.lppGps:
// MeshCore GPS format: int32 LE (4 bytes each) × 10000 for lat/lon, × 100 for alt
// See MESHCORE_BLE_PROTOCOL.md lines 336-337, 434-435, 977-978
final rawLat = reader.readInt32LE();
final rawLon = reader.readInt32LE();
final rawAlt = reader.readInt32LE();
// Standard Cayenne LPP GPS format (type 0x88):
// - Latitude: 3 bytes, signed 24-bit, big-endian, × 10000
// - Longitude: 3 bytes, signed 24-bit, big-endian, × 10000
// - Altitude: 3 bytes, signed 24-bit, big-endian, × 100
// Total: 9 bytes (not the 12 bytes used in MeshCore advertisements!)
// Read 3-byte signed big-endian integers
final latBytes = reader.readBytes(3);
int rawLat = (latBytes[0] << 16) | (latBytes[1] << 8) | latBytes[2];
// Sign extend from 24-bit to 32-bit
if (rawLat > 0x7FFFFF) rawLat = rawLat - 0x1000000;
final lonBytes = reader.readBytes(3);
int rawLon = (lonBytes[0] << 16) | (lonBytes[1] << 8) | lonBytes[2];
if (rawLon > 0x7FFFFF) rawLon = rawLon - 0x1000000;
final altBytes = reader.readBytes(3);
int rawAlt = (altBytes[0] << 16) | (altBytes[1] << 8) | altBytes[2];
if (rawAlt > 0x7FFFFF) rawAlt = rawAlt - 0x1000000;
// Decode: divide by scaling factors
final lat = rawLat / 10000.0; // Fixed: was 1000000.0 (100x error!)
final lon = rawLon / 10000.0; // Fixed: was 1000000.0 (100x error!)
final lat = rawLat / 10000.0;
final lon = rawLon / 10000.0;
final alt = rawAlt / 100.0;
debugPrint(
' GPS Location (raw int32 LE): lat=$rawLat (0x${rawLat.toRadixString(16)}), lon=$rawLon (0x${rawLon.toRadixString(16)}), alt=$rawAlt (0x${rawAlt.toRadixString(16)})',
' GPS Location (raw 24-bit BE): lat=$rawLat (0x${rawLat.toRadixString(16).padLeft(6, '0')}), lon=$rawLon (0x${rawLon.toRadixString(16).padLeft(6, '0')}), alt=$rawAlt (0x${rawAlt.toRadixString(16).padLeft(6, '0')})',
);
debugPrint(
' GPS Location (decoded): ${lat.toStringAsFixed(6)}°, ${lon.toStringAsFixed(6)}°, altitude=${alt.toStringAsFixed(2)}m',
@@ -240,7 +254,10 @@ class CayenneLppParser {
}
/// Create Cayenne LPP data for GPS location
/// MeshCore GPS format: int32 LE (4 bytes each) × 10000 for lat/lon, × 100 for alt
/// Standard Cayenne LPP GPS format (type 0x88):
/// - Latitude: 3 bytes, signed 24-bit, big-endian, × 10000
/// - Longitude: 3 bytes, signed 24-bit, big-endian, × 10000
/// - Altitude: 3 bytes, signed 24-bit, big-endian, × 100
static Uint8List createGpsData({
required double latitude,
required double longitude,
@@ -252,26 +269,27 @@ class CayenneLppParser {
buffer.add(channel);
buffer.add(MeshCoreConstants.lppGps);
// Latitude (int32 LE, 4 bytes, signed, 0.0001° precision)
final lat = (latitude * 10000).round();
buffer.add(lat & 0xFF); // Byte 0 (LSB)
// Latitude (signed 24-bit BE, 3 bytes, 0.0001° precision)
int lat = (latitude * 10000).round();
// Handle negative values (two's complement for 24-bit)
if (lat < 0) lat = lat + 0x1000000;
buffer.add((lat >> 16) & 0xFF); // Byte 0 (MSB)
buffer.add((lat >> 8) & 0xFF); // Byte 1
buffer.add((lat >> 16) & 0xFF); // Byte 2
buffer.add((lat >> 24) & 0xFF); // Byte 3 (MSB)
buffer.add(lat & 0xFF); // Byte 2 (LSB)
// Longitude (int32 LE, 4 bytes, signed, 0.0001° precision)
final lon = (longitude * 10000).round();
buffer.add(lon & 0xFF); // Byte 0 (LSB)
// Longitude (signed 24-bit BE, 3 bytes, 0.0001° precision)
int lon = (longitude * 10000).round();
if (lon < 0) lon = lon + 0x1000000;
buffer.add((lon >> 16) & 0xFF); // Byte 0 (MSB)
buffer.add((lon >> 8) & 0xFF); // Byte 1
buffer.add((lon >> 16) & 0xFF); // Byte 2
buffer.add((lon >> 24) & 0xFF); // Byte 3 (MSB)
buffer.add(lon & 0xFF); // Byte 2 (LSB)
// Altitude (int32 LE, 4 bytes, signed, 0.01m precision)
final alt = (altitude * 100).round();
buffer.add(alt & 0xFF); // Byte 0 (LSB)
// Altitude (signed 24-bit BE, 3 bytes, 0.01m precision)
int alt = (altitude * 100).round();
if (alt < 0) alt = alt + 0x1000000;
buffer.add((alt >> 16) & 0xFF); // Byte 0 (MSB)
buffer.add((alt >> 8) & 0xFF); // Byte 1
buffer.add((alt >> 16) & 0xFF); // Byte 2
buffer.add((alt >> 24) & 0xFF); // Byte 3 (MSB)
buffer.add(alt & 0xFF); // Byte 2 (LSB)
return Uint8List.fromList(buffer);
}

17
lib/widgets/contacts/contact_tile.dart
View File

@@ -30,6 +30,17 @@ class ContactTile extends StatelessWidget {
this.onNavigateToMap,
});
/// Get localized time since last seen
String _getLocalizedTimeSinceLastSeen(BuildContext context) {
final l10n = AppLocalizations.of(context)!;
final diff = DateTime.now().difference(contact.lastSeenTime);
if (diff.inMinutes < 1) return l10n.justNow;
if (diff.inMinutes < 60) return l10n.minutesAgo(diff.inMinutes);
if (diff.inHours < 24) return l10n.hoursAgo(diff.inHours);
return l10n.daysAgo(diff.inDays);
}
@override
Widget build(BuildContext context) {
final appProvider = context.watch<AppProvider>();
@@ -194,7 +205,7 @@ class ContactTile extends StatelessWidget {
),
const SizedBox(width: 4),
Text(
'${AppLocalizations.of(context)!.lastSeen}: ${contact.timeSinceLastSeen}',
'${AppLocalizations.of(context)!.lastSeen}: ${_getLocalizedTimeSinceLastSeen(context)}',
style: Theme.of(context).textTheme.labelSmall,
),
],
@@ -337,7 +348,7 @@ class ContactTile extends StatelessWidget {
),
const SizedBox(width: 4),
Text(
contact.timeSinceLastSeen,
_getLocalizedTimeSinceLastSeen(context),
style: Theme.of(context).textTheme.labelSmall,
),
if (location != null) ...[
@@ -662,7 +673,7 @@ class ContactTile extends StatelessWidget {
),
_DetailRow(
AppLocalizations.of(context)!.lastSeen,
contact.timeSinceLastSeen,
_getLocalizedTimeSinceLastSeen(context),
),
const SizedBox(height: 16),
// Room Login Status