PMIM-1 hardware support: UDP, IIXDR, inclinometer

Transport:
- NmeaStreamManager supports TCP and UDP modes
- NmeaConnectionPrefs replaces hardcoded 192.168.1.1:10110; defaults
  to UDP/10110 matching PMIM-1 spec (ESP32 AP at 192.168.4.1)
- LocationService reads prefs via startNmeaFromPrefs()

Parsing:
- NmeaParser.parseXdr() handles $IIXDR attitude (HEEL/PTCH in degrees)
  and baro (pressure in bar → hPa, air temp °C)
- New AttitudeData and NmeaBaroData sensor types

UI:
- Heel + pitch row in instrument sheet (hidden until data arrives)
- InclinometerView: canvas circle with rotating waterline (heel) and
  displaced dot (pitch), colorPrimary-tinted, respects night mode
- Inclinometer overlay top-left of map, appears on first attitude packet
- NMEA baro overrides device sensor reading when available

https://claude.ai/code/session_01KXYBuAHZkvv63DeUG6XaZD

10 files changed, 420 insertions, 88 deletions

diff --git a/android-app/app/src/main/kotlin/org/terst/nav/LocationService.kt b/android-app/app/src/main/kotlin/org/terst/nav/LocationService.kt
index 9440d49..c47c7a5 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/LocationService.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/LocationService.kt
@@ -23,9 +23,12 @@ import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.flow.asStateFlow
 import org.terst.nav.nmea.NmeaParser
 import org.terst.nav.nmea.NmeaStreamManager
+import org.terst.nav.nmea.NmeaTransport
+import org.terst.nav.sensors.AttitudeData
 import org.terst.nav.sensors.BoatSpeedData
 import org.terst.nav.sensors.DepthData
 import org.terst.nav.sensors.HeadingData
+import org.terst.nav.sensors.NmeaBaroData
 import org.terst.nav.sensors.WindData
 import org.terst.nav.gps.GpsPosition
 import org.terst.nav.data.model.SensorData
@@ -136,6 +139,20 @@ class LocationService : Service() {
             }
         }
 
+        // Collect NMEA Attitude Data (heel + pitch from PMIM-1 IIXDR)
+        serviceScope.launch {
+            nmeaStreamManager.nmeaAttitudeData.collectLatest { attitude ->
+                _nmeaAttitudeFlow.emit(attitude)
+            }
+        }
+
+        // Collect NMEA Baro Data (pressure + air temp from PMIM-1 IIXDR)
+        serviceScope.launch {
+            nmeaStreamManager.nmeaBaroData.collectLatest { baro ->
+                _nmeaBaroFlow.emit(baro)
+            }
+        }
+
         locationCallback = object : LocationCallback() {
             override fun onLocationResult(locationResult: LocationResult) {
                 locationResult.lastLocation?.let { location ->
@@ -240,9 +257,9 @@ class LocationService : Service() {
                     startLocationUpdatesInternal(PowerMode.ECONOMY)
                 }
                 barometerSensorManager.start()
-                val flags = (application as NavApplication).featureFlags
-                if (flags.isEnabled(org.terst.nav.settings.HardwareSource.NMEA_INSTRUMENTS)) {
-                    nmeaStreamManager.start(NMEA_GATEWAY_IP, NMEA_GATEWAY_PORT)
+                val featureFlags = (application as NavApplication).featureFlags
+                if (featureFlags.isEnabled(org.terst.nav.settings.HardwareSource.NMEA_INSTRUMENTS)) {
+                    startNmeaFromPrefs()
                 }
             }
             ACTION_STOP_FOREGROUND_SERVICE -> {
@@ -274,7 +291,7 @@ class LocationService : Service() {
             }
             ACTION_START_NMEA -> {
                 Log.d("LocationService", "Starting NMEA stream")
-                nmeaStreamManager.start(NMEA_GATEWAY_IP, NMEA_GATEWAY_PORT)
+                startNmeaFromPrefs()
             }
             ACTION_STOP_NMEA -> {
                 Log.d("LocationService", "Stopping NMEA stream")
@@ -317,6 +334,16 @@ class LocationService : Service() {
         fusedLocationClient.removeLocationUpdates(locationCallback)
     }
 
+    private fun startNmeaFromPrefs() {
+        val prefs = NmeaConnectionPrefs(this)
+        val transport = when (prefs.transport) {
+            NmeaConnectionPrefs.Transport.UDP -> NmeaTransport.UDP
+            NmeaConnectionPrefs.Transport.TCP -> NmeaTransport.TCP
+        }
+        nmeaStreamManager.start(prefs.tcpHost, prefs.port, transport)
+        Log.i("LocationService", "NMEA started: ${prefs.transport} port=${prefs.port}")
+    }
+
     fun setPowerMode(powerMode: PowerMode) {
         serviceScope.launch {
             if (_currentPowerMode.value != powerMode) {
@@ -395,9 +422,6 @@ class LocationService : Service() {
         const val EXTRA_TIDAL_VISIBILITY = "extra_tidal_visibility"
         const val EXTRA_WATCH_RADIUS = "extra_watch_radius"
 
-        private const val NMEA_GATEWAY_IP = "192.168.1.1"
-        private const val NMEA_GATEWAY_PORT = 10110
-
         private val _locationFlow = MutableSharedFlow<GpsPosition>(replay = 1)
         val locationFlow: SharedFlow<GpsPosition> get() = _locationFlow
 
@@ -431,6 +455,12 @@ class LocationService : Service() {
         private val _nmeaBoatSpeedDataFlow = MutableSharedFlow<BoatSpeedData>(replay = 1)
         val nmeaBoatSpeedData: SharedFlow<BoatSpeedData> get() = _nmeaBoatSpeedDataFlow
 
+        private val _nmeaAttitudeFlow = MutableSharedFlow<AttitudeData>(replay = 1)
+        val nmeaAttitudeFlow: SharedFlow<AttitudeData> get() = _nmeaAttitudeFlow
+
+        private val _nmeaBaroFlow = MutableSharedFlow<NmeaBaroData>(replay = 1)
+        val nmeaBaroFlow: SharedFlow<NmeaBaroData> get() = _nmeaBaroFlow
+
         private val _currentSpeedKt = MutableStateFlow<Double?>(null)
         private val _currentDirectionDeg = MutableStateFlow<Double?>(null)
 
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt b/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
index 69ca666..b66c20b 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
@@ -86,6 +86,7 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
     private lateinit var bottomSheet: CardView
     private lateinit var bottomNav: BottomNavigationView
     private lateinit var mapCrosshair: View
+    private lateinit var inclinometerView: org.terst.nav.ui.InclinometerView
 
     // HUD value TextViews
     private lateinit var hudSog: TextView
@@ -222,6 +223,7 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
         bottomSheet = findViewById(R.id.instrument_bottom_sheet)
         bottomNav = findViewById(R.id.bottom_navigation)
         mapCrosshair = findViewById(R.id.map_crosshair)
+        inclinometerView = findViewById(R.id.inclinometer_view)
 
         // HUD value views
         hudSog   = findViewById(R.id.hud_sog)
@@ -829,6 +831,28 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
             }
         }
         lifecycleScope.launch {
+            LocationService.nmeaAttitudeFlow.collect { attitude ->
+                val heelText  = "%+.1f".format(Locale.getDefault(), attitude.heelDeg)
+                val pitchText = "%+.1f".format(Locale.getDefault(), attitude.pitchDeg)
+                findViewById<android.widget.TextView>(R.id.value_heel)?.text  = heelText
+                findViewById<android.widget.TextView>(R.id.value_pitch)?.text = pitchText
+                findViewById<android.view.View>(R.id.attitude_row)?.visibility = android.view.View.VISIBLE
+                inclinometerView.heelDeg  = attitude.heelDeg
+                inclinometerView.pitchDeg = attitude.pitchDeg
+                inclinometerView.visibility = android.view.View.VISIBLE
+            }
+        }
+        lifecycleScope.launch {
+            LocationService.nmeaBaroFlow.collect { baro ->
+                lastBaroHpa = baro.pressureHpa
+                instrumentHandler?.updateConditions(baroHpa = baro.pressureHpa)
+                baro.airTempC?.let { tempC ->
+                    lastConditions = lastConditions?.copy(tempC = tempC.toDouble())
+                    instrumentHandler?.updateConditions(tempC = tempC.toDouble())
+                }
+            }
+        }
+        lifecycleScope.launch {
             LocationService.anchorWatchState.collect { state ->
                 safetyFragment.updateAnchorStatus(if (state.isActive) "Active: ${state.watchCircleRadiusMeters}m" else "Inactive")
             }
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/NmeaConnectionPrefs.kt b/android-app/app/src/main/kotlin/org/terst/nav/NmeaConnectionPrefs.kt
new file mode 100644
index 0000000..19ad7a2
--- /dev/null
+++ b/android-app/app/src/main/kotlin/org/terst/nav/NmeaConnectionPrefs.kt
@@ -0,0 +1,31 @@
+package org.terst.nav
+
+import android.content.Context
+
+class NmeaConnectionPrefs(context: Context) {
+
+    private val prefs = context.getSharedPreferences("nmea_connection", Context.MODE_PRIVATE)
+
+    enum class Transport { TCP, UDP }
+
+    var transport: Transport
+        get() = runCatching { Transport.valueOf(prefs.getString(KEY_TRANSPORT, null) ?: "") }
+                    .getOrDefault(Transport.UDP)
+        set(v) { prefs.edit().putString(KEY_TRANSPORT, v.name).apply() }
+
+    var tcpHost: String
+        get() = prefs.getString(KEY_HOST, DEFAULT_HOST) ?: DEFAULT_HOST
+        set(v) { prefs.edit().putString(KEY_HOST, v).apply() }
+
+    var port: Int
+        get() = prefs.getInt(KEY_PORT, DEFAULT_PORT)
+        set(v) { prefs.edit().putInt(KEY_PORT, v).apply() }
+
+    companion object {
+        private const val KEY_TRANSPORT = "transport"
+        private const val KEY_HOST      = "host"
+        private const val KEY_PORT      = "port"
+        const val DEFAULT_HOST = "192.168.4.1"
+        const val DEFAULT_PORT = 10110
+    }
+}
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/nmea/NmeaParser.kt b/android-app/app/src/main/kotlin/org/terst/nav/nmea/NmeaParser.kt
index 6a470b8..d634115 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/nmea/NmeaParser.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/nmea/NmeaParser.kt
@@ -1,9 +1,11 @@
 package org.terst.nav.nmea
 
 import org.terst.nav.gps.GpsPosition
+import org.terst.nav.sensors.AttitudeData
 import org.terst.nav.sensors.BoatSpeedData
 import org.terst.nav.sensors.DepthData
 import org.terst.nav.sensors.HeadingData
+import org.terst.nav.sensors.NmeaBaroData
 import org.terst.nav.sensors.WindData
 import java.util.Calendar
 import java.util.TimeZone
@@ -213,6 +215,7 @@ class NmeaParser {
             "DBT" -> parseDbt(sentence)
             "HDG", "HDM" -> parseHdg(sentence)
             "VHW" -> parseVhw(sentence)
+            "XDR" -> parseXdr(sentence)
             else -> null
         }
     }
@@ -251,6 +254,51 @@ class NmeaParser {
     }
 
     /**
+     * Parses $IIXDR (transducer data). Handles the two sentence types emitted by PMIM-1:
+     *
+     *   Attitude: $IIXDR,A,{heel},D,HEEL,A,{pitch},D,PTCH*xx
+     *   Baro:     $IIXDR,P,{bar},B,Barometer,C,{tempC},C,TempAir*xx
+     *
+     * Returns AttitudeData, NmeaBaroData, or null.
+     */
+    fun parseXdr(sentence: String): Any? {
+        if (sentence.isBlank()) return null
+        val body = if ('*' in sentence) sentence.substringBefore('*') else sentence
+        val fields = body.split(',')
+        if (fields.size < 5 || !fields[0].endsWith("XDR")) return null
+
+        val now = System.currentTimeMillis()
+        var heelDeg: Float? = null
+        var pitchDeg: Float? = null
+        var pressureHpa: Float? = null
+        var airTempC: Float? = null
+
+        var i = 1
+        while (i + 3 < fields.size) {
+            val type  = fields[i]
+            val value = fields[i + 1].toFloatOrNull()
+            val unit  = fields[i + 2]
+            val id    = fields[i + 3]
+            i += 4
+            if (value == null) continue
+            when {
+                type == "A" && unit == "D" && id.equals("HEEL", ignoreCase = true) -> heelDeg = value
+                type == "A" && unit == "D" && id.equals("PTCH", ignoreCase = true) -> pitchDeg = value
+                type == "P" && unit == "B" && id.equals("Barometer", ignoreCase = true) -> pressureHpa = value * 1000f
+                type == "C" && unit == "C" && id.equals("TempAir", ignoreCase = true) -> airTempC = value
+            }
+        }
+
+        return when {
+            heelDeg != null || pitchDeg != null ->
+                AttitudeData(heelDeg ?: 0f, pitchDeg ?: 0f, now)
+            pressureHpa != null ->
+                NmeaBaroData(pressureHpa, airTempC, now)
+            else -> null
+        }
+    }
+
+    /**
      * Combines NMEA time (HHMMSS.ss) and date (DDMMYY) into a Unix epoch milliseconds value.
      * Returns 0 on any parse failure.
      */
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/nmea/NmeaStreamManager.kt b/android-app/app/src/main/kotlin/org/terst/nav/nmea/NmeaStreamManager.kt
index 981b32e..17c6bfb 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/nmea/NmeaStreamManager.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/nmea/NmeaStreamManager.kt
@@ -12,16 +12,22 @@ import kotlinx.coroutines.flow.asSharedFlow
 import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import org.terst.nav.gps.GpsPosition
+import org.terst.nav.sensors.AttitudeData
 import org.terst.nav.sensors.BoatSpeedData
 import org.terst.nav.sensors.DepthData
 import org.terst.nav.sensors.HeadingData
+import org.terst.nav.sensors.NmeaBaroData
 import org.terst.nav.sensors.WindData
 import java.io.BufferedReader
 import java.io.InputStreamReader
+import java.net.DatagramPacket
+import java.net.DatagramSocket
 import java.net.InetSocketAddress
 import java.net.Socket
 import java.util.concurrent.atomic.AtomicBoolean
 
+enum class NmeaTransport { TCP, UDP }
+
 class NmeaStreamManager(
     private val parser: NmeaParser,
     private val connectionScope: CoroutineScope
@@ -29,101 +35,101 @@ class NmeaStreamManager(
     private var connectionJob: Job? = null
     private val isConnected = AtomicBoolean(false)
 
-    // Flows to emit parsed data
-    private val _nmeaGpsPosition = MutableSharedFlow<GpsPosition>(
-        replay = 0,
-        extraBufferCapacity = 1,
-        onBufferOverflow = BufferOverflow.DROP_OLDEST
-    )
-    val nmeaGpsPosition: SharedFlow<GpsPosition> = _nmeaGpsPosition.asSharedFlow()
-
-    private val _nmeaWindData = MutableSharedFlow<WindData>(
-        replay = 0,
-        extraBufferCapacity = 1,
-        onBufferOverflow = BufferOverflow.DROP_OLDEST
+    private fun <T> flow() = MutableSharedFlow<T>(
+        replay = 0, extraBufferCapacity = 1, onBufferOverflow = BufferOverflow.DROP_OLDEST
     )
-    val nmeaWindData: SharedFlow<WindData> = _nmeaWindData.asSharedFlow()
 
-    private val _nmeaDepthData = MutableSharedFlow<DepthData>(
-        replay = 0,
-        extraBufferCapacity = 1,
-        onBufferOverflow = BufferOverflow.DROP_OLDEST
-    )
-    val nmeaDepthData: SharedFlow<DepthData> = _nmeaDepthData.asSharedFlow()
+    private val _nmeaGpsPosition    = flow<GpsPosition>()
+    private val _nmeaWindData       = flow<WindData>()
+    private val _nmeaDepthData      = flow<DepthData>()
+    private val _nmeaHeadingData    = flow<HeadingData>()
+    private val _nmeaBoatSpeedData  = flow<BoatSpeedData>()
+    private val _nmeaAttitudeData   = flow<AttitudeData>()
+    private val _nmeaBaroData       = flow<NmeaBaroData>()
 
-    private val _nmeaHeadingData = MutableSharedFlow<HeadingData>(
-        replay = 0,
-        extraBufferCapacity = 1,
-        onBufferOverflow = BufferOverflow.DROP_OLDEST
-    )
-    val nmeaHeadingData: SharedFlow<HeadingData> = _nmeaHeadingData.asSharedFlow()
-
-    private val _nmeaBoatSpeedData = MutableSharedFlow<BoatSpeedData>(
-        replay = 0,
-        extraBufferCapacity = 1,
-        onBufferOverflow = BufferOverflow.DROP_OLDEST
-    )
-    val nmeaBoatSpeedData: SharedFlow<BoatSpeedData> = _nmeaBoatSpeedData.asSharedFlow()
+    val nmeaGpsPosition:   SharedFlow<GpsPosition>   = _nmeaGpsPosition.asSharedFlow()
+    val nmeaWindData:      SharedFlow<WindData>       = _nmeaWindData.asSharedFlow()
+    val nmeaDepthData:     SharedFlow<DepthData>      = _nmeaDepthData.asSharedFlow()
+    val nmeaHeadingData:   SharedFlow<HeadingData>    = _nmeaHeadingData.asSharedFlow()
+    val nmeaBoatSpeedData: SharedFlow<BoatSpeedData>  = _nmeaBoatSpeedData.asSharedFlow()
+    val nmeaAttitudeData:  SharedFlow<AttitudeData>   = _nmeaAttitudeData.asSharedFlow()
+    val nmeaBaroData:      SharedFlow<NmeaBaroData>   = _nmeaBaroData.asSharedFlow()
 
-    fun start(address: String, port: Int) {
-        if (connectionJob?.isActive == true) {
-            Log.d(TAG, "NMEA stream already running.")
-            return
+    fun start(address: String, port: Int, transport: NmeaTransport = NmeaTransport.TCP) {
+        if (connectionJob?.isActive == true) return
+        connectionJob = when (transport) {
+            NmeaTransport.TCP -> startTcp(address, port)
+            NmeaTransport.UDP -> startUdp(port)
         }
+    }
 
-        connectionJob = connectionScope.launch(Dispatchers.IO) {
-            while (isActive) {
-                if (!isConnected.get()) {
-                    Log.d(TAG, "Attempting to connect to NMEA source: $address:$port")
-                    try {
-                        Socket().use { socket ->
-                            socket.connect(InetSocketAddress(address, port), CONNECTION_TIMEOUT_MS)
-                            isConnected.set(true)
-                            Log.i(TAG, "Connected to NMEA source: $address:$port")
+    fun stop() {
+        connectionJob?.cancel()
+        connectionJob = null
+        isConnected.set(false)
+    }
 
-                            BufferedReader(InputStreamReader(socket.getInputStream())).use { reader ->
-                                var line: String?
-                                while (isActive && isConnected.get()) {
-                                    line = reader.readLine()
-                                    if (line != null) {
-                                        // Log.v(TAG, "NMEA: $line") // Too verbose for regular logging
-                                        parser.parse(line)?.let { parsedData ->
-                                            when (parsedData) {
-                                                is GpsPosition -> _nmeaGpsPosition.emit(parsedData)
-                                                is WindData -> _nmeaWindData.emit(parsedData)
-                                                is DepthData -> _nmeaDepthData.emit(parsedData)
-                                                is HeadingData -> _nmeaHeadingData.emit(parsedData)
-                                                is BoatSpeedData -> _nmeaBoatSpeedData.emit(parsedData)
-                                                else -> Log.w(TAG, "Unknown parsed NMEA data type: ${parsedData::class.simpleName}")
-                                            }
-                                        }
-                                    } else {
-                                        // End of stream, connection closed by server
-                                        Log.w(TAG, "NMEA stream ended, reconnecting...")
-                                        isConnected.set(false)
-                                        break
-                                    }
-                                }
-                            }
+    private fun startTcp(address: String, port: Int) = connectionScope.launch(Dispatchers.IO) {
+        while (isActive) {
+            Log.d(TAG, "TCP connecting to $address:$port")
+            try {
+                Socket().use { socket ->
+                    socket.connect(InetSocketAddress(address, port), CONNECTION_TIMEOUT_MS)
+                    isConnected.set(true)
+                    Log.i(TAG, "TCP connected to $address:$port")
+                    BufferedReader(InputStreamReader(socket.getInputStream())).use { reader ->
+                        var line: String?
+                        while (isActive) {
+                            line = reader.readLine() ?: break
+                            processLine(line)
                         }
-                    } catch (e: Exception) {
-                        Log.e(TAG, "NMEA connection error: ${e.message}", e)
-                        isConnected.set(false)
                     }
                 }
-                if (!isConnected.get()) {
-                    delay(RETRY_DELAY_MS)
+            } catch (e: Exception) {
+                Log.e(TAG, "TCP error: ${e.message}")
+            }
+            isConnected.set(false)
+            delay(RETRY_DELAY_MS)
+        }
+    }
+
+    private fun startUdp(port: Int) = connectionScope.launch(Dispatchers.IO) {
+        Log.i(TAG, "UDP listening on port $port")
+        try {
+            DatagramSocket(port).use { socket ->
+                isConnected.set(true)
+                val buffer = ByteArray(4096)
+                val packet = DatagramPacket(buffer, buffer.size)
+                while (isActive) {
+                    socket.receive(packet)
+                    val text = String(packet.data, 0, packet.length, Charsets.US_ASCII)
+                    text.split('\n').forEach { raw ->
+                        val line = raw.trimEnd('\r', ' ')
+                        if (line.isNotBlank()) processLine(line)
+                    }
                 }
             }
-            Log.d(TAG, "NMEA connection job finished.")
+        } catch (e: Exception) {
+            Log.e(TAG, "UDP error: ${e.message}")
+            isConnected.set(false)
         }
     }
 
-    fun stop() {
-        connectionJob?.cancel()
-        connectionJob = null
-        isConnected.set(false)
-        Log.i(TAG, "NMEA stream stopped.")
+    private fun processLine(line: String) {
+        parser.parse(line)?.let { parsed ->
+            connectionScope.launch {
+                when (parsed) {
+                    is GpsPosition   -> _nmeaGpsPosition.emit(parsed)
+                    is WindData      -> _nmeaWindData.emit(parsed)
+                    is DepthData     -> _nmeaDepthData.emit(parsed)
+                    is HeadingData   -> _nmeaHeadingData.emit(parsed)
+                    is BoatSpeedData -> _nmeaBoatSpeedData.emit(parsed)
+                    is AttitudeData  -> _nmeaAttitudeData.emit(parsed)
+                    is NmeaBaroData  -> _nmeaBaroData.emit(parsed)
+                    else -> Log.w(TAG, "Unhandled: ${parsed::class.simpleName}")
+                }
+            }
+        }
     }
 
     companion object {
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/sensors/AttitudeData.kt b/android-app/app/src/main/kotlin/org/terst/nav/sensors/AttitudeData.kt
new file mode 100644
index 0000000..1969c0e
--- /dev/null
+++ b/android-app/app/src/main/kotlin/org/terst/nav/sensors/AttitudeData.kt
@@ -0,0 +1,7 @@
+package org.terst.nav.sensors
+
+data class AttitudeData(
+    val heelDeg: Float,
+    val pitchDeg: Float,
+    val timestampMs: Long
+)
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/sensors/NmeaBaroData.kt b/android-app/app/src/main/kotlin/org/terst/nav/sensors/NmeaBaroData.kt
new file mode 100644
index 0000000..2f2bae5
--- /dev/null
+++ b/android-app/app/src/main/kotlin/org/terst/nav/sensors/NmeaBaroData.kt
@@ -0,0 +1,7 @@
+package org.terst.nav.sensors
+
+data class NmeaBaroData(
+    val pressureHpa: Float,
+    val airTempC: Float?,
+    val timestampMs: Long
+)
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/InclinometerView.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/InclinometerView.kt
new file mode 100644
index 0000000..c472375
--- /dev/null
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/InclinometerView.kt
@@ -0,0 +1,107 @@
+package org.terst.nav.ui
+
+import android.content.Context
+import android.graphics.Canvas
+import android.graphics.Color
+import android.graphics.Paint
+import android.util.AttributeSet
+import android.view.View
+import androidx.core.content.ContextCompat
+import org.terst.nav.R
+import kotlin.math.min
+
+/**
+ * Compact inclinometer showing heel (rotation) and pitch (dot displacement).
+ * Heel: the waterline rotates — starboard-down is positive.
+ * Pitch: dot displaces up (bow up = positive).
+ */
+class InclinometerView @JvmOverloads constructor(
+    context: Context,
+    attrs: AttributeSet? = null,
+    defStyleAttr: Int = 0
+) : View(context, attrs, defStyleAttr) {
+
+    var heelDeg: Float = 0f
+        set(value) { field = value; invalidate() }
+
+    var pitchDeg: Float = 0f
+        set(value) { field = value; invalidate() }
+
+    private val bgPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+        style = Paint.Style.FILL
+        color = Color.parseColor("#CC000000")
+    }
+
+    private val borderPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+        style = Paint.Style.STROKE
+        strokeWidth = 1.5f
+        color = Color.parseColor("#44FFFFFF")
+    }
+
+    private val horizonPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+        style = Paint.Style.STROKE
+        strokeCap = Paint.Cap.ROUND
+    }
+
+    private val dotPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+        style = Paint.Style.FILL
+    }
+
+    private val tickPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+        style = Paint.Style.STROKE
+        strokeWidth = 1f
+        color = Color.parseColor("#33FFFFFF")
+    }
+
+    override fun onAttachedToWindow() {
+        super.onAttachedToWindow()
+        val primary = try {
+            val tv = android.util.TypedValue()
+            context.theme.resolveAttribute(com.google.android.material.R.attr.colorPrimary, tv, true)
+            tv.data
+        } catch (e: Exception) {
+            Color.parseColor("#2B8FC4")
+        }
+        horizonPaint.color = primary
+        horizonPaint.strokeWidth = density * 2.5f
+        dotPaint.color = primary
+    }
+
+    private val density get() = resources.displayMetrics.density
+
+    override fun onDraw(canvas: Canvas) {
+        val cx = width / 2f
+        val cy = height / 2f
+        val r  = min(width, height) / 2f - density * 2f
+
+        // Background + border
+        canvas.drawCircle(cx, cy, r, bgPaint)
+        canvas.drawCircle(cx, cy, r, borderPaint)
+
+        // Clip to circle
+        canvas.save()
+        canvas.clipRect(cx - r, cy - r, cx + r, cy + r)
+
+        // Tick marks at 10° intervals (subtle)
+        for (angle in listOf(-30f, -20f, -10f, 10f, 20f, 30f)) {
+            canvas.save()
+            canvas.rotate(angle, cx, cy)
+            canvas.drawLine(cx, cy - r, cx, cy - r + density * 5f, tickPaint)
+            canvas.restore()
+        }
+
+        // Heel: rotate the horizon line
+        canvas.save()
+        canvas.rotate(heelDeg, cx, cy)
+        val lineLen = r * 0.78f
+        canvas.drawLine(cx - lineLen, cy, cx + lineLen, cy, horizonPaint)
+        canvas.restore()
+
+        // Pitch: displace dot (up = bow up = negative Y, clamped to ±30°)
+        val pitchClamped = pitchDeg.coerceIn(-30f, 30f)
+        val pitchOffsetY = -(pitchClamped / 30f) * r * 0.35f
+        canvas.drawCircle(cx, cy + pitchOffsetY, density * 3.5f, dotPaint)
+
+        canvas.restore()
+    }
+}
diff --git a/android-app/app/src/main/res/layout/activity_main.xml b/android-app/app/src/main/res/layout/activity_main.xml
index ca13105..d3b7942 100644
--- a/android-app/app/src/main/res/layout/activity_main.xml
+++ b/android-app/app/src/main/res/layout/activity_main.xml
@@ -53,6 +53,17 @@
                 app:layout_constraintTop_toBottomOf="@id/nav_hud"
                 app:layout_constraintEnd_toEndOf="parent" />
 
+            <!-- Inclinometer overlay — top-left, hidden until attitude data arrives -->
+            <org.terst.nav.ui.InclinometerView
+                android:id="@+id/inclinometer_view"
+                android:layout_width="72dp"
+                android:layout_height="72dp"
+                android:layout_marginStart="12dp"
+                android:layout_marginTop="8dp"
+                android:visibility="gone"
+                app:layout_constraintTop_toBottomOf="@id/nav_hud"
+                app:layout_constraintStart_toStartOf="parent" />
+
             <!-- Night mode toggle FAB -->
             <com.google.android.material.floatingactionbutton.FloatingActionButton
                 android:id="@+id/fab_night_mode"
diff --git a/android-app/app/src/main/res/layout/layout_instruments_sheet.xml b/android-app/app/src/main/res/layout/layout_instruments_sheet.xml
index 5e58009..96298f9 100644
--- a/android-app/app/src/main/res/layout/layout_instruments_sheet.xml
+++ b/android-app/app/src/main/res/layout/layout_instruments_sheet.xml
@@ -158,6 +158,67 @@
 
     </LinearLayout>
 
+    <!-- Heel + Pitch row — hidden until PMIM attitude data arrives -->
+    <LinearLayout
+        android:id="@+id/attitude_row"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="horizontal"
+        android:visibility="gone"
+        app:layout_constraintTop_toBottomOf="@id/conditions_header"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent">
+
+        <LinearLayout
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:orientation="vertical"
+            android:gravity="center"
+            android:padding="8dp">
+            <TextView style="@style/InstrumentLabel" android:text="Heel" />
+            <LinearLayout
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_gravity="center_horizontal"
+                android:orientation="horizontal"
+                android:gravity="center_vertical">
+                <TextView
+                    android:id="@+id/value_heel"
+                    style="@style/InstrumentPrimaryValue"
+                    tools:text="-5.2" />
+                <TextView
+                    style="@style/InstrumentUnit"
+                    android:text="°" />
+            </LinearLayout>
+        </LinearLayout>
+
+        <LinearLayout
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:orientation="vertical"
+            android:gravity="center"
+            android:padding="8dp">
+            <TextView style="@style/InstrumentLabel" android:text="Pitch" />
+            <LinearLayout
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_gravity="center_horizontal"
+                android:orientation="horizontal"
+                android:gravity="center_vertical">
+                <TextView
+                    android:id="@+id/value_pitch"
+                    style="@style/InstrumentPrimaryValue"
+                    tools:text="+2.1" />
+                <TextView
+                    style="@style/InstrumentUnit"
+                    android:text="°" />
+            </LinearLayout>
+        </LinearLayout>
+
+    </LinearLayout>
+
     <!-- Animated wave divider — colors adapt via wave_sky/sea color resources -->
     <org.terst.nav.ui.WaveView
         android:id="@+id/wave_divider"
@@ -165,7 +226,7 @@
         android:layout_height="72dp"
         android:layout_marginStart="-16dp"
         android:layout_marginEnd="-16dp"
-        app:layout_constraintTop_toBottomOf="@id/conditions_header"
+        app:layout_constraintTop_toBottomOf="@id/attitude_row"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintEnd_toEndOf="parent" />